11institutetext:  Astrobiology Research Unit, Université de Liège, Allée du 6
Août 19C, B-4000 Liège, Belgium 22institutetext: Space Sciences, Technologies
and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6
Août 19C, B-4000 Liège, Belgium 33institutetext: Cavendish Laboratory, JJ
Thomson Avenue, Cambridge, CB3 0HE, UK 44institutetext: University of Colorado
Boulder, Boulder, CO 80309, USA 55institutetext: Instituto de Astrofísica de
Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
66institutetext: Komaba Institute for Science, The University of Tokyo, 3-8-1
Komaba, Meguro, Tokyo 153-8902, Japan 77institutetext: Astrobiology Center,
2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 88institutetext: Instituto de
Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain
99institutetext: AIM, CEA, CNRS, Université Paris-Saclay, Université de Paris,
F-91191 Gif-sur-Yvette, France 1010institutetext: Department of Multi-
Disciplinary Sciences, Graduate School of Arts and Sciences, The University of
Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan 1111institutetext: Center
for Astrophysics and Space Sciences, UC San Diego, UCSD Mail Code 0424, 9500
Gilman Drive, La Jolla, CA 92093-0424, USA 1212institutetext: National
Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
1313institutetext: Department of Earth, Atmospheric and Planetary Science,
Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA
02139, USA 1414institutetext: Kavli Institute for Astrophysics and Space
Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
1515institutetext: Department of Physics & Astronomy, Vanderbilt University,
6301 Stevenson Center Ln., Nashville, TN 37235, USA 1616institutetext: Univ.
Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France 1717institutetext:
Observatoire de Genève, Département d’Astronomie, Université de Genève, Chemin
Pegasi 51b, 1290 Versoix, Switzerland 1818institutetext: NASA Ames Research
Center, Moffett Field, CA 94035, USA 1919institutetext: Department of
Astronomy and Carl Sagan Institute, Cornell University, 302 Space Sciences
Building, Ithaca, NY 14853, USA 2020institutetext: School of Physics &
Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
2121institutetext: SETI Institute, Mountain View, CA 94043, USA
2222institutetext: Center for Astrophysics — Harvard & Smithsonian, 60 Garden
Street, Cambridge, MA, 02138, USA 2323institutetext: Caltech/IPAC, Mail Code
100-22, 1200 E. California Blvd., Pasadena, CA 91125, USA 2424institutetext:
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA
02139, USA 2525institutetext: Department of Astrophysical Sciences, Princeton
University, 4 Ivy Lane, Princeton, NJ 08544, USA 2626institutetext: Center for
Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012,
Bern, Switzerland 2727institutetext: Universidad Nacional Autónoma de México,
Instituto de Astronomía, AP 70-264, Ciudad de México, 04510, México
2828institutetext: Universidad Nacional Autónoma de México, Instituto de
Astronomía, AP 106, Ensenada 22800, BC, México 2929institutetext: European
Space Agency (ESA), European Space Research and Technology Centre (ESTEC),
Keplerlaan 1, 2201 AZ Noordwijk, Netherlands 3030institutetext: Subaru
Telescope, 650 N. Aohoku Place, Hilo, HI 96720, USA 3131institutetext:
Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4
7AL, United Kingdom 3232institutetext: Departamento de Astrofísica,
Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
3333institutetext: Department of Earth and Planetary Science, Graduate School
of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033,
Japan 3434institutetext: Department of Astronomy, School of Science, The
Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka,
Tokyo, Japan 3535institutetext: Lowell Observatory, 1400 W. Mars Hill Rd.,
Flagstaff, AZ 86001, USA 3636institutetext: Bay Area Environmental Research
Institute, Moffett Field, CA 94035, USA 3737institutetext: Department of
Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo,
Bunkyo-ku, Tokyo 113-0033, Japan 3838institutetext: Department of Aeronautics
and Astronautics, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
3939institutetext: Space Telescope Science Institute, 3700 San Martin Drive,
Baltimore, MD, 21218, USA

# Two temperate super-Earths transiting a nearby late-type M dwarf††thanks:
The photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/

L. Delrez ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ C.A. Murray ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ F.J. Pozuelos ID Two temperate super-Earths transiting a
nearby late-type M dwarf††thanks: The photometric and radial velocity data
used in this work are available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ N. Narita ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ E. Ducrot ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Paris Region Fellow, Marie
Sklodowska-Curie ActionParis Region Fellow, Marie Sklodowska-Curie Action M.
Timmermans Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/
N. Watanabe ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ A.J. Burgasser ID Two temperate super-Earths transiting a
nearby late-type M dwarf††thanks: The photometric and radial velocity data
used in this work are available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ T. Hirano ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ B.V. Rackham ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/51 Pegasi b Fellow51 Pegasi b
Fellow K.G. Stassun ID Two temperate super-Earths transiting a nearby late-
type M dwarf††thanks: The photometric and radial velocity data used in this
work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/
V. Van Grootel ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ C. Aganze ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ M. Cointepas Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ S. Howell ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ L. Kaltenegger ID Two temperate super-Earths transiting a
nearby late-type M dwarf††thanks: The photometric and radial velocity data
used in this work are available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ P. Niraula ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ D. Sebastian ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ J.M. Almenara Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ K. Barkaoui ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ T.A. Baycroft Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ X. Bonfils ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ F. Bouchy ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ A. Burdanov ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ D.A. Caldwell Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ D. Charbonneau ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ D.R. Ciardi ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ K.A. Collins Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ T. Daylan ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ B.-O. Demory ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ J. de Wit Two temperate super-
Earths transiting a nearby late-type M dwarf††thanks: The photometric and
radial velocity data used in this work are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ G. Dransfield ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ S.B. Fajardo-Acosta Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ M.
Fausnaugh ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ A. Fukui ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ E. Furlan ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ L.J. Garcia ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ C.L. Gnilka Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ Y. Gómez Maqueo Chew ID Two temperate super-Earths transiting
a nearby late-type M dwarf††thanks: The photometric and radial velocity data
used in this work are available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ M.A. Gómez-Muñoz ID Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/
M.N. Günther ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ESA Research FellowESA Research Fellow H. Harakawa Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ K. Heng
ID Two temperate super-Earths transiting a nearby late-type M dwarf††thanks:
The photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ M.J.
Hooton ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ Y. Hori ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ M. Ikoma ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/
E. Jehin ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ J.M. Jenkins ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ T. Kagetani ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ K. Kawauchi ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ T. Kimura Two temperate super-Earths transiting a nearby late-
type M dwarf††thanks: The photometric and radial velocity data used in this
work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ T. Kodama ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ T. Kotani Two temperate super-Earths transiting a nearby late-
type M dwarf††thanks: The photometric and radial velocity data used in this
work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ V. Krishnamurthy ID Two temperate super-Earths transiting a
nearby late-type M dwarf††thanks: The photometric and radial velocity data
used in this work are available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ T. Kudo ID Two temperate super-
Earths transiting a nearby late-type M dwarf††thanks: The photometric and
radial velocity data used in this work are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ V. Kunovac ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ N. Kusakabe ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ D.W. Latham ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ C. Littlefield Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ J. McCormac Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ C. Melis ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ M. Mori ID Two temperate super-
Earths transiting a nearby late-type M dwarf††thanks: The photometric and
radial velocity data used in this work are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ F. Murgas ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ E. Palle ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ P.P. Pedersen Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ D. Queloz ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/
G. Ricker ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ L. Sabin ID Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ N. Schanche Two temperate super-Earths transiting a nearby
late-type M dwarf††thanks: The photometric and radial velocity data used in
this work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ U. Schroffenegger Two temperate super-Earths transiting a
nearby late-type M dwarf††thanks: The photometric and radial velocity data
used in this work are available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ S. Seager Two temperate super-
Earths transiting a nearby late-type M dwarf††thanks: The photometric and
radial velocity data used in this work are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ B. Shiao Two temperate super-
Earths transiting a nearby late-type M dwarf††thanks: The photometric and
radial velocity data used in this work are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/
S. Sohy Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ M.R. Standing ID Two temperate super-Earths transiting a
nearby late-type M dwarf††thanks: The photometric and radial velocity data
used in this work are available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ M. Tamura ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ C.A. Theissen ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/NASA Sagan FellowNASA Sagan
Fellow S.J. Thompson ID Two temperate super-Earths transiting a nearby late-
type M dwarf††thanks: The photometric and radial velocity data used in this
work are available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/
A.H.M.J. Triaud ID Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/Two temperate super-Earths transiting a nearby late-type M
dwarf††thanks: The photometric and radial velocity data used in this work are
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-
bin/qcat?J/A+A/ R. Vanderspek ID Two temperate super-Earths transiting a
nearby late-type M dwarf††thanks: The photometric and radial velocity data
used in this work are available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ S. Vievard ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ R.D. Wells ID Two temperate
super-Earths transiting a nearby late-type M dwarf††thanks: The photometric
and radial velocity data used in this work are available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ J.N. Winn Two temperate super-
Earths transiting a nearby late-type M dwarf††thanks: The photometric and
radial velocity data used in this work are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ Y. Zou ID Two temperate super-
Earths transiting a nearby late-type M dwarf††thanks: The photometric and
radial velocity data used in this work are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two temperate super-Earths
transiting a nearby late-type M dwarf††thanks: The photometric and radial
velocity data used in this work are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ S. Zúñiga-Fernández ID Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ M. Gillon
ID Two temperate super-Earths transiting a nearby late-type M dwarf††thanks:
The photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/Two
temperate super-Earths transiting a nearby late-type M dwarf††thanks: The
photometric and radial velocity data used in this work are available in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/

(Received …; accepted …)

###### Abstract

Context. In the age of JWST, temperate terrestrial exoplanets transiting
nearby late-type M dwarfs provide unique opportunities for characterising
their atmospheres, as well as searching for biosignature gases. In this
context, the benchmark TRAPPIST-1 planetary system has garnered the interest
of a broad scientific community.

Aims. We report here the discovery and validation of two temperate super-
Earths transiting LP 890-9 (TOI-4306, SPECULOOS-2), a relatively low-activity
nearby (32 pc) M6V star. The inner planet, LP 890-9 b, was first detected by
TESS (and identified as TOI-4306.01) based on four sectors of data. Intensive
photometric monitoring of the system with the SPECULOOS Southern Observatory
then led to the discovery of a second outer transiting planet, LP 890-9 c
(also identified as SPECULOOS-2 c), previously undetected by TESS. The orbital
period of this second planet was later confirmed by MuSCAT3 follow-up
observations.

Methods. We first inferred the properties of the host star by analyzing its
Lick/Kast optical and IRTF/SpeX near-infrared spectra, as well as its
broadband spectral energy distribution, and Gaia parallax. We then derived the
properties of the two planets by modelling multi-colour transit photometry
from TESS, SPECULOOS-South, MuSCAT3, ExTrA, TRAPPIST-South, and SAINT-EX.
Archival imaging, Gemini-South/Zorro high-resolution imaging, and Subaru/IRD
radial velocities also support our planetary interpretation.

Results. With a mass of $0.118\pm 0.002$ $M_{\odot}$, a radius of $0.1556\pm
0.0086$ $R_{\odot}$, and an effective temperature of $2850\pm 75$ K, LP 890-9
is the second-coolest star found to host planets, after TRAPPIST-1. The inner
planet has an orbital period of 2.73 d, a radius of $1.320_{-0.027}^{+0.053}$
$R_{\oplus}$, and receives an incident stellar flux of $4.09\pm 0.12$
$S_{\oplus}$. The outer planet has a similar size of $1.367_{-0.039}^{+0.055}$
$R_{\oplus}$ and an orbital period of 8.46 d. With an incident stellar flux of
$0.906\pm 0.026$ $S_{\oplus}$, it is located within the conservative habitable
zone, very close to its inner limit (runaway greenhouse). Although the masses
of the two planets remain to be measured, we estimated their potential for
atmospheric characterisation via transmission spectroscopy using a mass-radius
relationship and found that, after the TRAPPIST-1 planets, LP 890-9 c is the
second-most favourable habitable-zone terrestrial planet known so far
(assuming for this comparison a similar atmosphere for all planets).

Conclusions. The discovery of this remarkable system offers another rare
opportunity to study temperate terrestrial planets around our smallest and
coolest neighbours.

###### Key Words.:

Planets and satellites: detection – Stars: individual: LP 890-9 – Stars:
individual: TIC 44898913 – Stars: individual: TOI-4306 – Stars: individual:
SPECULOOS-2 – Techniques: photometric

##  1 Introduction

One main goal of modern astronomy is the identification and atmospheric
characterisation of temperate terrestrial exoplanets, to understand how
frequently and under which conditions life may exist around other stars.
Terrestrial planets transiting nearby late-type M dwarfs are key in this
endeavor. Indeed, for a given planet (fixed radius, mass, and equilibrium
temperature), the signal-to-noise ratio (S/N) of atmospheric spectral features
probed by eclipse (transit or occultation) spectroscopy increases for smaller
and cooler host stars (e.g. Kaltenegger & Traub 2009, de Wit & Seager 2013).
As a consequence, fewer eclipse observations need to be co-added to achieve a
significant atmospheric detection. In this regard, the low luminosity of the
latest-type M stars is also a considerable advantage, as it results in more
frequent planetary eclipses for a given stellar irradiation, meaning that it
takes much less time to obtain a certain amount of in-eclipse observations.
The S/N of atmospheric spectral features also scales inversely with the
distance from the Earth to the host star, making the nearest late-type M
dwarfs the best targets to search for transiting temperate terrestrial planets
whose atmospheres could be characterised with current or next-generation
facilities.

These considerations motivated the development of the SPECULOOS project
(Search for habitable Planets EClipsing ULtra-cOOl Stars; Gillon 2018,
Burdanov et al. 2018, Delrez et al. 2018), an exoplanet transit survey
targeting a volume-limited (40 pc) sample of about 1700 late-type dwarfs with
spectral type M6 and later – mostly stars, but also $\sim$5% brown dwarfs
(Sebastian et al., 2021) – using a network of 1m-class robotic telescopes.
While SPECULOOS started its scientific operations officially in 2019 (Jehin et
al., 2018), it was initiated in 2011 as a prototype survey (Gillon et al.,
2013) targeting fifty of the brightest southern late-type M dwarfs with the
TRAPPIST-South telescope. This prototype survey led to the discovery of the
TRAPPIST-1 system111Internally, the SPECULOOS team also refers to this
discovery as SPECULOOS-1, since it was the first official detection as part of
the SPECULOOS project., consisting of seven temperate Earth-sized planets
transiting a nearby (12 pc) M8V star (Gillon et al., 2016, 2017; Luger et al.,
2017). The discovery of this benchmark system has caused a flurry of
theoretical and observational follow-up studies, so that the TRAPPIST-1
planets are today the best-studied terrestrial planets outside our Solar
System (Agol et al., 2021). They are also the most favourable targets found so
far in the temperate terrestrial regime for atmospheric characterisation with
the recently-launched JWST (see, e.g., Lustig-Yaeger et al. 2019; Gillon et
al. 2020) and are already approved for substantial ($\sim$200 hr) Cycle 1
Guaranteed Time Observations and General Observers programs.

Besides TRAPPIST-1, only two other transiting systems are currently known
around M dwarfs with spectral type M5 or later: LHS 3844 (Vanderspek et al.,
2019) and LP 791-18 (Crossfield et al., 2019). LHS 3844 b is an ultra-short-
period super-Earth (1.3 $R_{\oplus}$) that orbits its M5V star every 11 hours.
LP 791-18 is an M6V star transited by a super-Earth (1.1 $R_{\oplus}$) and a
sub-Neptune (2.3 $R_{\oplus}$) with respective orbital periods of 0.95 and
4.99 days. Both systems were detected by the Transiting Exoplanet Survey
Satellite (TESS, Ricker et al. 2015). While TESS is efficient at detecting
small transiting planets around early-to-mid-type M dwarfs (e.g. Günther et
al. 2019; Kostov et al. 2019; Demory et al. 2020; Wells et al. 2021; Schanche
et al. 2022; Gan et al. 2022), its detection potential drops sharply for
objects later than $\sim$M5 (Sullivan et al., 2015; Barclay et al., 2018;
Sebastian et al., 2021), due to their faintness in TESS’s bandpass. The two
systems mentioned above demonstrate that TESS is able to detect some short-
period and/or $\gtrsim$2 $R_{\oplus}$ planets around some bright late-type M
stars. However, possible additional transiting planets in the same systems
with longer orbital periods and/or smaller radii may be missed due to the
limited photometric precision. With its near-infrared-optimised cameras and
custom ‘$I+z$’ filters (transmittance $>$90% from 750 to $\sim$1100 nm),
SPECULOOS is specifically designed to achieve high photometric precision on
late-type/ultra-cool dwarf stars and can detect those additional transiting
planets, thus allowing an effective synergy between the two surveys.

In this paper, we present a discovery that leverages that synergy: the
detection of two temperate super-Earths transiting the nearby M6-type dwarf
star LP 890-9. The inner planet was first detected by TESS based on four
sectors of data. The announcement of this planet candidate (identified by TESS
as TOI-4306.01) triggered intensive photometric monitoring of the target with
the SPECULOOS Southern Observatory, which led to the discovery of a second
longer-period transiting planet (identified by SPECULOOS as SPECULOOS-2 c),
previously undetected by TESS. The orbital period of this second planet was
later confirmed by MuSCAT3 follow-up observations. We validated the planetary
nature of the system through follow-up observations from several ground-based
facilities, including high-precision multi-colour photometry, spectroscopy,
high-angular-resolution imaging, and archival images.

The paper is structured as follows. In Sect. 2, we describe the contributing
facilities and datasets used in the validation and characterisation of the
system. We infer the properties of the host star in Sect. 3 and validate the
planetary nature of the two transit signals in Sect. 4. In Sect. 5, we present
our detailed analysis of the photometry, including a global transit analysis
to derive the system’s properties (Sect. 5.1), a search for additional
transiting planets in the TESS and SPECULOOS-South data and an assessment of
their detection limits (Sect. 5.2), as well as a study of the stellar
variability (Sect. 5.3). Sect. 6 describes our analysis of Subaru/IRD radial
velocities and derivation of preliminary mass constraints. In Sect. 7, we
present a dynamical analysis of the system, including studies of its tidal
evolution and long-term stability. Finally, we discuss the system’s
properties, potential habitability, and prospects for follow-up in Sect. 8,
before concluding in Sect. 9.

##  2 Observations

In this section, we present all the observations of LP 890-9 obtained with
TESS and ground-based follow-up facilities.

Figure 1: TESS target pixel files of LP 890-9 for sectors 4 (upper left), 5
(upper right), 31 (lower left), and 32 (lower right). The pixel scale is
21$\arcsec$ per pixel. The electron counts are colour-coded. The target is
indicated by a white cross. Nearby sources identified in Gaia DR2 (Gaia
Collaboration et al., 2018), up to 6 magnitudes in contrast with LP 890-9, are
shown as red circles. The symbol size is proportional to the magnitude
contrast with the target. The apertures used by the SPOC pipeline to extract
the photometry are shown as red shaded regions. These plots were created with
tpfplotter (Aller et al., 2020).

###  2.1 TESS photometry

LP 890-9 (TIC 44898913) is part of the TESS Cool Dwarf catalogue (Muirhead et
al., 2018). It was identified as an attractive target for a transit search
with TESS, and thus included in the TESS Candidate Target List (Stassun et
al., 2018b). The star was observed at a two-minute cadence during sectors 4-5
(18 October $-$ 11 December 2018) of the primary mission and again two years
later during sectors 31-32 (21 October $-$ 17 December 2020) of the extended
mission. The observations were acquired with CCDs 1 (sectors 5 and 32) and 2
(sectors 4 and 31) on Camera 2. The data were processed with the TESS Science
Processing Operations Center (SPOC) pipeline (Jenkins et al., 2016) at NASA
Ames Research Center and searched for periodic transit signals (Jenkins, 2002;
Jenkins et al., 2010, 2020). While the analysis of the first two sectors did
not identify any convincing signal, the addition of two more sectors during
the extended mission revealed a $\sim$0.7%-deep transit-like signature at a
period of 2.73 days, with a Multiple Event Statistic (MES) of 8.3. The TESS
Science Office reviewed the SPOC Data Validation Report (Twicken et al., 2018;
Li et al., 2019) for this signal and announced the planet candidate
TOI-4306.01 on 21 July 2021 (Guerrero et al., 2021). Fig. 1 shows the target
pixel files and photometric apertures used by SPOC for each of the four
sectors, with the locations of nearby Gaia DR2 sources, up to 6 magnitudes in
contrast with LP 890-9. None of them lie within the SPOC photometric
apertures.

We retrieved the Presearch Data Conditioning Simple Aperture Photometry
(PDCSAP, Stumpe et al. 2012; Smith et al. 2012; Stumpe et al. 2014) from the
Mikulski Archive for Space Telescopes (MAST) and removed all data points for
which the quality flag was not zero. The resulting light curves are shown in
Fig. 2, together with the transit times. As noted in the data release
notes222https://archive.stsci.edu/missions/tess/doc/tess_drn/tess_sector_04_drn05_v04.pdf
for sector 4, communications between the instrument and spacecraft were
interrupted between BJD times 2 458 418.54 and 2 458 421.21, during which time
no data or telemetry were collected, hence a gap in the light curve. The
photometry obtained after this instrument anomaly was impacted by some thermal
effects, as the camera temperature increased by $\sim$20 degrees before
returning to nominal within three days. We thus decided to exclude this region
of the light curve (marked in orange in Fig. 2) from our analysis.

Figure 2: TESS photometry of LP 890-9. For each of the four sectors, the 2-minute data points (in grey) have been binned into 30-minute intervals to produce the black points, with error bars corresponding to the root-mean-square of the uncertainties of the points in the bins. The transits of LP 890-9 b and c are indicated by red and blue dotted lines, respectively. The region marked in orange in sector 4 was impacted by thermal effects and thus excluded from our analysis. Date (UT) | Facility | Bandpass | Exp. time (s) | Notes
---|---|---|---|---
10 Aug. 2021 | SSO/Europa | $I+z$ | 35 | b full
10 Aug. 2021 | TRAPPIST-South | blue-blocking | 120 | b full
21 Aug. 2021 | SSO/Callisto | $i^{\prime}$ | 92 | b full
21 Aug. 2021 | SSO/Io | $I+z$ | 39 | b full
1 Sept. 2021 | SSO/Europa | $i^{\prime}$ | 92 | b full
1 Sept. 2021 | SSO/Io | $z^{\prime}$ | 49 | b full
20 Sept. 2021 | SSO/Ganymede | $r^{\prime}$ | 180 | b full
20 Sept. 2021 | SSO/Io | $r^{\prime}$ | 180 | b full
20 Sept. 2021 | SSO/Europa | $r^{\prime}$ | 180 | b full
20 Sept. 2021 | ExTrA1 | 0.85$-$1.55 $\mu$m | 60 | b full
20 Sept. 2021 | ExTrA2 | 0.85$-$1.55 $\mu$m | 60 | b full
28 Sept. 2021 | MuSCAT3 | $g^{\prime}$ | 120 | b full
28 Sept. 2021 | MuSCAT3 | $r^{\prime}$ | 120 | b full
28 Sept. 2021 | MuSCAT3 | $i^{\prime}$ | 110 | b full
28 Sept. 2021 | MuSCAT3 | $z_{\mathrm{s}}$ | 100 | b full
1 Oct. 2021 | SSO/Europa | $I+z$ | 39 | b full
16 Oct. 2021 | SSO/Io | $I+z$ | 39 | c full
23 Oct. 2021 | SSO/Europa | $I+z$ | 39 | b full
28 Oct. 2021 | MuSCAT3 | $g^{\prime}$ | 120 | b full
28 Oct. 2021 | MuSCAT3 | $r^{\prime}$ | 120 | b full
28 Oct. 2021 | MuSCAT3 | $i^{\prime}$ | 55 | b full
28 Oct. 2021 | MuSCAT3 | $z_{\mathrm{s}}$ | 29 | b full
2 Nov. 2021 | SSO/Europa | $I+z$ | 39 | c full
8 Nov. 2021 | MuSCAT3 | $g^{\prime}$ | 120 | b full
8 Nov. 2021 | MuSCAT3 | $r^{\prime}$ | 120 | b full
8 Nov. 2021 | MuSCAT3 | $i^{\prime}$ | 55 | b full
8 Nov. 2021 | MuSCAT3 | $z_{\mathrm{s}}$ | 29 | b full
11 Nov. 2021 | SSO/Europa | $z^{\prime}$ | 49 | b full
19 Nov. 2021 | SSO/Europa | $I+z$ | 39 | c full
30 Nov. 2021 | SSO/Europa | $I+z$ | 39 | b full
30 Nov. 2021 | SAINT-EX | $I+z$ | 128 | b partial
3 Dec. 2021 | SSO/Europa | $I+z$ | 39 | b full
2 Jan. 2022 | SSO/Europa | $I+z$ | 39 | b full
17 Jan. 2022 | MuSCAT3 | $r^{\prime}$ | 120 | c full
17 Jan. 2022 | MuSCAT3 | $i^{\prime}$ | 55 | c full
17 Jan. 2022 | MuSCAT3 | $z_{\mathrm{s}}$ | 29 | c full
Table 1: Ground-based transit light curves of LP 890-9 used in our global
transit analysis. The last column shows which planet was observed and whether
the transit was fully or only partially covered.

###  2.2 Ground-based follow-up photometry

We obtained follow-up photometry of multiple transit events of the candidate
TOI-4306.01 with several ground-based facilities and different bandpasses, as
part of TESS Follow-up Observing Program (TFOP) Sub-Group 1 (SG1) for Seeing-
Limited Photometry. The goals of these observations were to confirm that the
transit signal detected by TESS was on the expected star, assess its
chromaticity, and obtain higher-precision transit light curves compared to the
TESS data. In addition to observations of transits associated with
TOI-4306.01, we also monitored the target intensively with the SPECULOOS
Southern Observatory (see Sect. 2.2.1), to search for possible additional
transiting planets that may not have been detected by TESS and study the
variability of the star. As mentioned previously, this monitoring revealed a
second longer-period transiting planet candidate (identified by SPECULOOS as
SPECULOOS-2 c), whose orbital period was later confirmed by MuSCAT3 follow-up
observations (see Sect. 2.2.4). We describe all the ground-based photometric
observations in the following sections and summarise the transit light curves
of both planets in Table 1.

####  2.2.1 SPECULOOS-South

The SPECULOOS Southern Observatory (SSO, Burdanov et al., 2018; Delrez et al.,
2018; Gillon, 2018; Jehin et al., 2018) consists of four 1-m telescopes (Io,
Europa, Ganymede, and Callisto) located at ESO Paranal Observatory in Chile.
Each telescope is equipped with a deep-depletion 2K$\times$2K CCD detector
optimised for the near infrared, providing a 12$\arcmin$ $\times$ 12$\arcmin$
field of view with a pixel scale of 0.35$\arcsec$ per pixel.

Fourteen transit light curves of TOI-4306.01 were obtained with SSO in several
filters (see Table 1): three in $r^{\prime}$, two in $i^{\prime}$, two in
$z^{\prime}$, and seven in the special ‘$I+z$’ filter. As mentioned above, we
also performed an intense photometric monitoring of the system outside of
these transits, gathering in total 614.45 hours of observations spread over
119 nights between 9 August 2021 and 20 January 2022. For this monitoring, we
used the $I+z$ filter with an exposure time of 39 seconds to optimise the S/N.
These data revealed a second transit signal, with a transit depth of about
0.6%. Three transits of this second object (identified by SPECULOOS as
SPECULOOS-2 c) were observed with SSO (see Table 1), all in the $I+z$ filter.
Each pair of consecutive transits was separated by 16.914 days. The only
fractional period alias that remained possible based on the SSO data was 8.457
days (16.914/2 days). Shorter period aliases were excluded, as they would have
produced several other detectable transits in the SSO data. The period of
8.457 days, which was $\sim$1.7 times more likely than the 16.914-days period
based on geometric transit probability, was later confirmed thanks to
photometric follow-up observations from Hawaii using MuSCAT3 (see Sect.
2.2.4).

The data were processed with the automatic SSO pipeline, which is described in
detail in Murray et al. (2020). This pipeline first performs standard image
reduction steps, applying bias, dark, and flat-field corrections. Star
detection, astrometric solving, and aperture photometry are then conducted
using the casutools package (Irwin et al., 2004). For the observations
presented here, the selected aperture radii are between 8 and 16 pixels
(2.8–5.6$\arcsec$), depending on the filter and night. The target’s light
curve is then generated by an automated differential photometry algorithm,
which uses a weighted ensemble of comparison stars to correct for most
atmospheric and instrumental effects. Finally, this light curve is corrected
for the effects of time-varying telluric water vapour (see also Pedersen et
al., in prep.), which can significantly affect near-infrared differential
photometry of very red objects such as LP 890-9.

####  2.2.2 TRAPPIST-South

We observed a transit of TOI-4306.01 on 10 August 2021 with the 0.6-m
TRAPPIST-South telescope (Gillon et al., 2011; Jehin et al., 2011), located at
ESO La Silla Observatory in Chile. The wide ‘blue-blocking’ filter
(transmittance $>$90% from 520 to $\sim$1100 nm) was used for these
observations, with an exposure time of 120 seconds. The data were processed
using the prose open-source333https://github.com/lgrcia/prose Python
framework, which is described in detail in Garcia et al. (2022). We used a
photometric aperture of 8.7 pixels (5.6 $\arcsec$).

####  2.2.3 ExTrA

ExTrA (Bonfils et al., 2015) is a near-infrared (0.85 to 1.55 $\mu$m) multi-
object spectrograph fed by three 60-cm telescopes located at La Silla
Observatory in Chile. One full transit of TOI-4306.01 was observed on 20
September 2021 using two ExTrA telescopes. We used 8$\arcsec$ aperture fibres
and the low-resolution mode ($R{\sim}20$) of the spectrograph with an exposure
time of 60 seconds. Five fibre positioners are used at the focal plane of each
telescope to select light from the target and four comparison stars. As
comparison stars, we observed 2MASS J04172127-2815315, 2MASS
J04191176-2812449, 2MASS J04181010-2753179, and 2MASS J04164312-2759006 with
2MASS $J$-magnitudes (Skrutskie et al., 2006) and Gaia effective temperatures
(Gaia Collaboration et al., 2018) similar to the target. The resulting ExTrA
data were analysed using a custom data reduction software, described in more
detail in Cointepas et al. (2021).

####  2.2.4 MuSCAT3

We observed three transits of TOI-4306.01 in the $g^{\prime}$, $r^{\prime}$,
$i^{\prime}$, and $z_{\mathrm{s}}$ bands simultaneously by using the multi-
band imager MuSCAT3 on the Faulkes Telescope North of Las Cumbres Observatory
on Haleakala, Hawaii (Narita et al., 2020). MuSCAT3 is equipped with four
2k$\times$ 2k CCD cameras for the four channels, each providing a pixel scale
of 0.266$\arcsec$ pixel-1 and a field of view of 9.1$\arcmin$ $\times$
9.1$\arcmin$. The first transit was observed on 28 September 2021 (UT) with
exposure times of 120, 120, 110, and 100 s in the $g^{\prime}$, $r^{\prime}$,
$i^{\prime}$ and $z_{\mathrm{s}}$ bands, respectively. The second transit was
observed on 28 October 2021 (UT) with exposure times of 120, 120, 55, and 29 s
in the $g^{\prime}$, $r^{\prime}$, $i^{\prime}$ and $z_{\mathrm{s}}$ bands,
respectively. The third transit was taken on 8 November 2021 (UT) with the
same exposure times as the second transit. All observations were conducted
without defocussing. On the night of the first, second, and third transits,
the lunar phase was 21, 22, and 3 days, and the angular distance between the
target and the moon was 53, 70, and 125 degrees, respectively.

We also observed one transit of the second planet candidate detected by SSO
(SPECULOOS-2 c) with MuSCAT3 on 17 January 2022 (UT). The goal of these
observations was to firmly confirm the orbital period of 8.457 days, since the
less likely 16.914-days period would not have produced a transit during that
night. We used exposure times of 120, 120, 55, and 29 s for the $g^{\prime}$,
$r^{\prime}$, $i’$ and $z_{\mathrm{s}}$ bands, respectively. The lunar phase
and the moon distance were 14 days and 64 degrees, respectively. The sky
background was bright because the almost-full moon was located nearby. Thus,
the photometric precision in the $g^{\prime}$ and $r^{\prime}$ bands was not
as good as for the previous observations of TOI-4306.01. Nonetheless, the
transit was clearly detected in the $i^{\prime}$ and $z^{\prime}$ bands (see
Fig. 10), thus confirming the orbital period of 8.457 days. We note that we
did not use the $g^{\prime}$-band light curve in our global transit analysis
(see Sect. 5.1), as its scatter ($\sim$2.9%) was too large for it to be
useful.

The obtained images were calibrated by the BANZAI pipeline (McCully et al.,
2018). We performed aperture photometry on the calibrated images using a
custom pipeline (Fukui et al., 2011). We optimised the aperture radius and
combination of comparison stars for each night and each band so that the
dispersion of the light curve was minimised. The adopted aperture radii were
10–14 pixels, depending on the band and night.

####  2.2.5 SAINT-EX

A partial transit of TOI-4306.01 was observed on 30 November 2021 with the 1-m
SAINT-EX telescope, located at the Observatorio Astronómico Nacional in the
Sierra de San Pedro Mártir in Mexico (Sabin et al., 2018; Demory et al.,
2020). SAINT-EX is a twin of the SSO telescopes but the camera is operated
using a different readout mode and higher gain so that it can observe brighter
stars. For these observations, we used the $I+z$ filter with an exposure time
of 128 seconds. The data were reduced using the custom PRINCE pipeline, which
is detailed in Demory et al. (2020). A weighted principal component analysis
(PCA) approach (Bailey, 2012) was used to correct the light curve for
systematics that are common between the target and comparison stars.

###  2.3 Spectroscopy

In this section, we describe the spectroscopic observations of LP 890-9 that
we obtained to characterise the star (low-resolution near-infrared and optical
spectra, Sect. 2.3.1 and 2.3.2) and to measure radial velocities (high-
resolution near-infrared spectra, Sect. 2.3.3).

####  2.3.1 IRTF/SpeX

We obtained a low-resolution near-infrared spectrum of LP 890-9 with the SpeX
spectrograph (Rayner et al., 2003) on the 3.2-m NASA Infrared Telescope
Facility (IRTF) on two nights, 30 August 2021 and 23 November 2021 (UT). The
conditions on both nights were clear with seeing of 0.7-0.8$\arcsec$. We used
the short-wavelength cross-dispersed (SXD) mode with the 0.3$\arcsec$ $\times$
15$\arcsec$ slit aligned to the parallactic angle, giving a 0.8–2.5 $\mu$m
spectrum with a resolving power of $R{\sim}2000$. In August, we collected
three ABBA nod sequences (12 exposures) with integration times of 179.8
seconds per exposure, giving a total integration time of 36 minutes. In
November, we collected a single ABBA nod sequence with integration times of
599.6 seconds per exposure, giving a total integration time of 40 minutes. We
collected a set of standard SXD flat-field and arc-lamp exposures immediately
after the science exposures, followed by a set of six exposures of the A0 V
star HD 27016 ($V=7.77$) in August and the A0 V star HD 22687 ($V=8.55$) in
November for flux and telluric calibration. We reduced the data using Spextool
v4.1 (Cushing et al., 2004), following the standard instructions in the
Spextool User’s Manual444Available at
http://irtfweb.ifa.hawaii.edu/~spex/observer/.. The final spectra have a
median S/N of $\sim$100, with peaks in the $J$, $H$, and $K$ bands of 126,
136, and 126, respectively.

####  2.3.2 Lick/Kast

We obtained a low-resolution optical spectrum of LP 890-9 with the Kast Double
Spectrograph on the 3m Shane Telescope at Lick Observatory on 14 November 2021
(UT) in clear conditions with 2$\arcsec$ seeing. This instrument provides
simultaneous blue and red optical spectra with parallel spectrograph cameras.
Our analysis focussed on red optical data obtained with the 600/7500 grating
and 1.5$\arcsec$-wide slit, providing 6000-9000 Å spectra at an average
resolution of $\lambda/\Delta\lambda$ $\approx$ 2500\. The source was observed
with 6 exposures of 600 s each within an hour of transit and at an average
airmass of 2.5. The flux calibrator Feige 110 (Hamuy et al., 1992, 1994) was
observed on the same night, and dome illuminated flat field and arc lamp
exposures were obtained at the start of the night for pixel response and
wavelength calibration. Data were reduced using the KastRedux
package555https://github.com/aburgasser/kastredux. (Burgasser et al. in
prep.), and included image reduction (flat-fielding, bad pixel masking, and
linearity correction), optimal extraction, wavelength calibration, and flux
density calibration. No attempt was made to correct for telluric absorption.
The data have a median S/N of $\sim$50 at 7400 Å.

####  2.3.3 Subaru/IRD

To measure radial velocities (RVs) for LP 890-9, we obtained high-resolution
near-infrared spectra with the InfraRed Doppler (IRD) spectrograph mounted on
the Subaru 8.2-m telescope (Tamura et al., 2012; Kotani et al., 2018). IRD is
a fibre-fed, temperature-stabilised spectrograph, having a wavelength coverage
of 970–1730 nm ($Y$, $J$, and $H$-bands) with a spectral resolution of
$\approx 70,000$. For the simultaneous wavelength reference, laser-frequency
comb (LFC) light was routinely injected into IRD using a secondary fibre. A
total of 14 frames were secured for LP 890-9 between 10 September 2021 and 10
January 2022 (UT). Due to instrumental trouble in one of the two IRD
detectors, only $H$-band spectra ($>1450$ nm) were obtained for the three
frames taken in January 2022. Given the faintness of the target ($J=12.258$),
the exposure times were set to 1800 seconds for all frames.

We reduced the raw IRD data as per the reduction procedure in Hirano et al.
(2020), and extracted both stellar and LFC spectra, whose wavelengths were
calibrated using the Thorium-Argon hollow cathode lamp. The reduced stellar
spectra had a typical S/N of $\approx 25$ per pixel at 1000 nm. Using IRD’s
analysis pipeline for RV measurements (Hirano et al., 2020), we computed
relative RVs for the individual stellar spectra. In doing so, both $YJ$ and
$H$-band spectra were analysed for all frames except the ones (three frames)
in January 2022, for which we were only able to measure RVs for $H$-band
spectra. The resulting RV measurements are given in Table 6. The typical
measurement errors are $10-15$ m/s and $7-10$ m/s for the $YJ$-band and the
$H$-band spectra, respectively.

###  2.4 High-angular-resolution imaging

Exoplanet host stars can have spatially close companions which are bound or
line-of-sight objects. These companions can create a false-positive transit
signal if, for example, they are an eclipsing binary or other variable star.
But mainly, close companions cause ‘third-light’ flux contamination that leads
to an underestimated planetary radius if not accounted for in the transit
model (Ciardi et al., 2015). Companion stars can also cause non-detections of
small planets residing with the same exoplanetary system (Lester et al.,
2021). Thus, to search for close-in (bound) companions unresolved in TESS or
other ground-based follow-up observations, we obtained high-resolution imaging
speckle observations of LP 890-9.

LP 890-9 was observed on 20 March 2022 (UT) using the Zorro speckle instrument
on the Gemini South 8-m telescope (Scott et al., 2021). Zorro provides
simultaneous speckle imaging in two bands (562 nm and 832 nm) with output data
products including a reconstructed image with robust contrast limits on
companion detections (e.g. Howell et al. 2016). Twenty-five sets of 1000
$\times$ 0.06-sec exposures were collected for this faint star and subjected
to Fourier analysis in our standard reduction pipeline (Howell et al., 2011).
Fig. 3 shows our final 5$\sigma$ contrast curves and the 832 nm reconstructed
speckle image. We find that LP 890-9 is a single star with no companion
brighter than 4-5 magnitudes below that of the target star from
$\sim$0.2$\arcsec$ out to 1.2$\arcsec$. At the distance of LP 890-9 (32.3 pc),
these angular limits correspond to spatial limits of 6.5 to 39 au.

Figure 3: Zorro speckle imaging 5$\sigma$ contrast curves at 562 (blue) and
832 nm (red), along with the 832 nm reconstructed image.

##  3 Stellar properties

LP 890-9 is a relatively low-activity late-type M dwarf located at 32 pc. In
this section, we describe the methodology used to determine its properties,
which are given in Table 2 together with its catalogued photometric and
astrometric parameters.

Table 2: Properties of the host star. Property | Value | Source
---|---|---
Designations |
LP | 890-9 | Luyten (1979)
TIC | 44898913 | Stassun et al. (2018b)
TOI | 4306 |
SPECULOOS | 2 |
2MASS | J04163114-2818526 | Skrutskie et al. (2006)
Gaia EDR3 | 4886243456388510720 | Gaia Collaboration et al. (2021)
Astrometric properties |
RA (J2000) | 04:16:31.16 |  Gaia EDR3 (Gaia Collaboration et al., 2021)
Dec (J2000) |  $-$28:18:52.95 |  Gaia EDR3 (Gaia Collaboration et al., 2021)
$\mathrm{\mu_{RA}}$ (mas $\mathrm{yr}^{-1}$) | $218.569\pm 0.036$ |  Gaia EDR3 (Gaia Collaboration et al., 2021)
$\mathrm{\mu_{Dec}}$ (mas $\mathrm{yr}^{-1}$) | $-251.145\pm 0.047$ |  Gaia EDR3 (Gaia Collaboration et al., 2021)
Parallax (mas) | $30.933\pm 0.042$ |  Gaia EDR3 (Gaia Collaboration et al., 2021)
Distance (pc) | $32.33\pm 0.05$ |  Gaia EDR3 (Gaia Collaboration et al., 2021)
$V_{\mathrm{tan}}$ (km/s) | $51.02\pm 0.07$ |  Gaia EDR3 (Gaia Collaboration et al., 2021)
RV (km/s) | $27.94\pm 0.60$ | Sect. 3.3
$U$ (km/s) | $17.66\pm 0.27$ | Sect. 3.3
$V$ (km/s) | $-57.77\pm 0.30$ | Sect. 3.3
$W$ (km/s) | $5.48\pm 0.39$ | Sect. 3.3
Photometric magnitudes |
TESS (mag) | 14.2683 $\pm$ 0.0076 | Stassun et al. (2018b)
$V$ (mag) | 18.0 $\pm$ 0.2 | Muirhead et al. (2018)
$g$ (mag) | 18.4422 $\pm$ 0.0072 | Pan-STARRS1 (Chambers et al., 2016)
$r$ (mag) | 17.1365 $\pm$ 0.0050 | Pan-STARRS1 (Chambers et al., 2016)
$i$ (mag) | 15.0975 $\pm$ 0.0026 | Pan-STARRS1 (Chambers et al., 2016)
$z$ (mag) | 14.1593 $\pm$ 0.0013 | Pan-STARRS1 (Chambers et al., 2016)
$y$ (mag) | 13.6454 $\pm$ 0.0044 | Pan-STARRS1 (Chambers et al., 2016)
Gaia (mag) | 15.7913 $\pm$ 0.0028 |  Gaia EDR3 (Gaia Collaboration et al., 2021)
$J$ (mag) | 12.258 $\pm$ 0.023 | 2MASS (Skrutskie et al., 2006)
$H$ (mag) | 11.692 $\pm$ 0.025 | 2MASS (Skrutskie et al., 2006)
$K$ (mag) | 11.344 $\pm$ 0.023 | 2MASS (Skrutskie et al., 2006)
$W$1 (mag) | 11.129 $\pm$ 0.061 | WISE (Cutri et al., 2021)
$W$2 (mag) | 10.920 $\pm$ 0.020 | WISE (Cutri et al., 2021)
$W$3 (mag) | 10.715 $\pm$ 0.083 | WISE (Cutri et al., 2021)
Spectroscopic and derived properties |
Optical SpT | M6.0 $\pm$ 0.5 | Kast spectrum (Sect. 3.1)
Near-infrared SpT | M6.0 $\pm$ 0.5 | SpeX spectrum (Sect. 3.1)
$\mathrm{[Fe/H]}$ (dex) | $-0.028\pm 0.089$ | SpeX spectrum (Sect. 3.1)
$T_{\mathrm{eff}}$ (K) | $2850\pm 75$ | SED fit (Sect. 3.2)
$F_{\mathrm{bol}}$ ($10^{-11}$ $\mathrm{erg\,s^{-1}\,cm^{-2}}$) | $4.41\pm 0.15$ | SED fit (Sect. 3.2)
$L_{\star}$ ($10^{-3}$ $L_{\odot}$) | $1.441\pm 0.038$ |  $F_{\mathrm{bol}}$ \+ parallax (Sect. 3.2)
$R_{\star}$ ($R_{\odot}$) | $0.1556\pm 0.0086$ |  $F_{\mathrm{bol}}$ \+ $T_{\mathrm{eff}}$ \+ parallax (Sect. 3.2)
$M_{\star}$ ($M_{\odot}$) | $0.118\pm 0.002$ | Evol. modelling + $L_{\star}$ \+ $\mathrm{[Fe/H]}$ (Sect. 3.2)
log $g_{\star}$ (cgs) | $5.126_{-0.047}^{+0.050}$ |  $M_{\star}$ \+ $R_{\star}$
$\rho_{\star}$ ($\mathrm{g\,cm^{-3}}$) | $44.2_{-6.7}^{+8.3}$ |  $M_{\star}$ \+ $R_{\star}$
Age (Gyr) | 7.2${}^{+2.2}_{-3.1}$ |  $UVW$ \+ $\mathrm{[Fe/H]}$ (Sect. 3.3)

###  3.1 Spectroscopic analysis

Fig. 4 displays the reduced Kast spectrum compared to late-M dwarf SDSS
optical spectral templates from Bochanski et al. (2007). The best overall
match is M6. We note that this is somewhat later than the index-based
classification reported in Cruz & Reid (2002), and index-based classifications
derived from relations defined in Lépine et al. (2003) and Riddick et al.
(2007), all of which yield a classification of M5. Our template comparison
rules this classification out. The spectrum shows a weak H$\alpha$ emission
line with an equivalent width of $-1.5\pm 0.3$ Å corresponding to
$\log_{10}(L_{\rm{H\alpha}}/L_{\rm{bol}})$ = $-4.58\pm 0.10$ based on the
$\chi$ factor relation of Douglas et al. (2014), making LP 890-9 a relatively
low-activity M dwarf (cf. Newton et al. 2017). Metallicity indices from Lépine
et al. (2007, 2013); Dhital et al. (2012); and Zhang et al. (2019) all
indicate a dwarf metallicity classification, with a modest subsolar
metallicity ([Fe/H] $\approx$ $-$0.17 to $-$0.12 based on Mann et al. 2013).

We performed a parallel set of analyses on the infrared SpeX spectra of LP
890-9 using the SpeX Prism Library Analysis Toolkit (SPLAT, Burgasser & Splat
Development Team, 2017). Results from both observations were identical. We
obtained a spectral classification of M6.0 $\pm$ 0.5 by comparison to spectral
standards (Kirkpatrick et al., 2010), as shown in Fig. 5. With the SpeX
spectrum, we can also obtain a metallicity estimate. We used SPLAT to measure
the equivalent widths of the K-band Na i and Ca i doublets and the H2O–K2
index (Rojas-Ayala et al., 2012). We then estimated the stellar metallicity
using the Mann et al. (2014) relation between these observables and [Fe/H]. We
used a Monte Carlo approach to calculate the uncertainty in our estimate,
drawing $10^{6}$ samples from normal distributions given by the means and
standard deviations of the measurements. We calculated the mean and standard
deviation of the resulting values and, adding in quadrature the systematic
uncertainty of the relation (0.07), we arrived at our final metallicity
estimate of $\textrm{[Fe/H]}=-0.028\pm 0.089$ based on the August data,
consistent at $1\sigma$ with our estimate from the optical spectrum. The
November data gave identical results within the uncertainties.

Figure 4:  Lick/Kast red optical spectrum of LP 890-9 (solid black lines)
compared to M5 (dashed magenta line), M6 (solid magenta line), and M7 (dotted
magenta line) optical spectral templates from Bochanski et al. (2007). The
three spectral templates are offset by a constant to facilitate comparison.
Key atomic and molecular spectral features are labelled, and the inset box
shows a close-up of the region around the 6563 Å H$\alpha$ emission line and
6708 Å Li I absorption line (not detected).  Figure 5:  SpeX spectrum of LP
890-9 (blue) obtained in August 2021. The SpeX Prism spectrum of the M6.0
standard LHS 1375 (Kirkpatrick et al., 2010) is shown in grey for comparison.
Prominent spectral features are highlighted, and regions of strong telluric
absorption are shaded. The bottom line gives the measurement uncertainty.

###  3.2 SED fitting and evolutionary modelling

We performed an analysis of the broadband spectral energy distribution (SED)
of the star together with the Gaia EDR3 parallax (with no systematic offset
applied; see, e.g., Stassun & Torres, 2021), in order to determine an
empirical measurement of the stellar radius, following the procedures
described in Stassun & Torres (2016) and Stassun et al. (2017, 2018a). We
pulled the $JHK_{S}$ magnitudes from 2MASS (Skrutskie et al., 2006), the
$W1W2W3$ magnitudes from WISE (Cutri et al., 2021), and the $griz$ magnitudes
from Pan-STARRS (Chambers et al., 2016). Together, the available photometry
spans the full stellar SED over the wavelength range 0.4–10 $\mu$m (see Fig.
6).

Figure 6: Spectral energy distribution (SED) of LP 890-9. The red symbols
represent the observed photometric measurements (the horizontal bars represent
the effective width of the bandpass). The blue symbols are the model fluxes
from the best-fit NextGen atmosphere model (black curve).

We performed a fit using NextGen stellar atmosphere models, with the free
parameters being the effective temperature ($T_{\rm eff}$) and metallicity
([Fe/H]). The remaining free parameter is the extinction $A_{V}$, which we
fixed at zero due to the star’s proximity. The resulting fit (Fig. 6) has a
reduced $\chi^{2}$ of 1.7, with best fit $T_{\rm eff}=2850\pm 75$ K and [Fe/H]
= $0.0\pm 0.5$. Integrating the model SED gives the bolometric flux at Earth,
$F_{\rm bol}=4.41\pm 0.15\times 10^{-11}$ erg s-1 cm-2. Taking the $F_{\rm
bol}$ and $T_{\rm eff}$, together with the Gaia EDR3 parallax, gives the
stellar radius, $R_{\star}=0.1556\pm 0.0086\>R_{\odot}$.

For the mass, we applied stellar evolutionary modelling, using the models for
very low-mass stars presented in Fernandes et al. (2019). We used as
constraints the luminosity derived from $F_{\rm bol}$ and the Gaia EDR3
parallax ($L_{\star}=1.4406\pm 0.0375\times 10^{-3}L_{\odot}$), the
metallicity inferred in Sect. 3.1, and assuming an age $\gtrsim$ 2 Gyr (see
Sect. 3.3)666The luminosity of very low-mass stars evolves very slowly with
time once the star has turned on core H-burning and has reached the main
sequence. Hence, assuming any age $\gtrsim 2$ Gyr will provide the same
resulting mass., we obtained a stellar mass of $0.118\pm 0.002\>M_{\odot}$.
This uncertainty reflects the error propagation on the stellar luminosity and
metallicity, but also the uncertainty associated with the input physics of the
stellar models (Van Grootel et al., 2018). Considering the stellar radius
estimate from SED fitting, this gives a mean stellar density of
$\rho_{\star}=44.2_{-6.7}^{+8.3}$ g cm-3 ($\rho_{\star}=31.3_{-4.7}^{+5.9}$
$\rho_{\odot}$).

###  3.3 Estimated stellar age

The age of LP 890-9 was estimated by comparing its $UVW$ kinematics and
metallicity to local stars, an adaptation of the method used to age-date
TRAPPIST-1 (Burgasser & Mamajek, 2017). The comparison sample was drawn from
the GALAH Data Release 3 catalogue (Buder et al., 2021), for which ages have
been estimated using the Bayesian Stellar Parameter Estimation (BSTEP) code by
Sharma et al. (2018). The match set assumes individual $UVW$ velocities within
10 km/s of LP 890-9 and within 1$\sigma$ of the metallicity. Figure 7 compares
the distribution of ages in the full GALAH sample and the match set, which
shows a broad peak at 7.2${}^{+2.2}_{-3.1}$ Gyr (i.e., 4–9 Gyr). This age is
broadly consistent with the kinematics of the source, which are consistent
with the thin disk Galactic population (8% probability thick disk) based on
Bensby et al. (2003).

Figure 7: Distribution of ages in the full GALAH DR3 sample (light grey
histogram) and sources that match the $UVW$ and metallicity of LP 890-9 to
within 10 km/s and 1$\sigma$, respectively (dark grey histogram). The latter
has a broad peak at 7.2${}^{+2.2}_{-3.1}$ Gyr (yellow line with uncertainties
indicated by the green shaded region), which we take as an estimate for the
age of LP 890-9. Figure 8: Imaging of the present-day position of LP 890-9
over 64 years, to assess for a current blend with an unresolved background
object. Archival images from POSS I (1957), POSS II (1994), and Pan-STARRS
(2014) are presented, along with a stack image from one night of observation
with SSO/Europa (2021). For each image, the position of LP 890-9 during the
SSO/Europa observations is shown as a white circle.

##  4 Planet validation

###  4.1 TESS data validation report

As an initial step for false-positive vetting and before obtaining the ground-
based follow-up observations described in Sect. 2, we first closely examined
the TESS Data Validation Report (Twicken et al., 2018; Li et al., 2019)
combining all four sectors (4, 5, 31, and 32) provided by the SPOC pipeline.
TOI-4306.01 successfully passed the eclipsing binary discrimination tests: the
odd and even transit depths agreed to within 0.06$\sigma$, and no significant
secondary eclipse was detected. TOI-4306.01 also passed the difference image
centroid offset test, which did not reveal any significant offset between the
transit source and the target (3.02$\pm$3.41 arcseconds), that would otherwise
suggest a blend of multiple stars (e.g., background star or stellar system)
and possible source confusion. In addition, the statistical bootstrap test
estimated at only 2.6 $\times 10^{-17}$ the probability that the signal is a
false alarm due to noise fluctuations in the light curve (e.g., stellar
variability or residual instrumental systematics).

We note that TOI-4306.01 failed the ghost diagnostic test, which involves
correlating flux time series derived from photometric core and halo aperture
pixels against the transit model. A higher correlation for the halo compared
to the core may indicate that the transit signal does not originate from the
target, but is caused instead by scattered light or a background object, such
as a background eclipsing binary. For TOI-4306.01, the test returned a
slightly higher correlation statistic777The correlation statistic is defined
as
$\frac{\tilde{b}\boldsymbol{\cdot}\tilde{s}}{\sqrt{\tilde{s}\boldsymbol{\cdot}\tilde{s}}}$
where $\tilde{b}$ is the whitened core or halo aperture flux time series and
$\tilde{s}$ is the whitened transit model light curve for the given planet
candidate (Twicken et al., 2018). for the halo (5.17) than the core (4.72).
However, the recovery of the transit signal with ground-based telescopes (see
Sect. 4.2) excludes the possibility that it was caused by scattered light or
other instrumental artefacts in the TESS data. Furthermore, archival imaging
(see Sect. 4.3) allows us to exclude any background object as the source of
TOI-4306.01’s transits.

###  4.2 Follow-up photometry

Owing to TESS’s large pixel scale of 21$\arcsec$ per pixel, it is not uncommon
that the photometric apertures used by SPOC to extract the light curves also
include some flux from contaminating stars. In this context, ground-based
follow-up photometry at a higher spatial resolution is important to explore
the possible contamination from nearby sources and confirm that the target
star is the source of the transits. Fig. 1 shows that LP 890-9 is relatively
isolated. SPOC reports only a small amount of contamination from outside
sources, ranging from 2.2 to 5.3% of the total flux depending on the sector
and aperture used (the PDCSAP photometry is corrected for this contamination).
The closest known Gaia DR2 source (Gaia Collaboration et al., 2018), labelled
‘2’ in Fig. 1, is 43.24$\arcsec$ away and about 3 magnitudes fainter (TESS-
mag=17.02, Stassun et al. 2018b). LP 890-9 is clearly resolved in the
SPECULOOS-South images, which have a pixel scale of 0.35$\arcsec$ per pixel,
thus allowing the extraction of light curves with photometric apertures of
only a few arcseconds (see Sect. 2.2.1). The smallest aperture that was tested
was 1.4$\arcsec$ (4 pixels). No transit event was observed on any nearby star,
while transits with a depth matching that of TOI-4306.01 were clearly detected
on the target star at the predicted times.

Our follow-up transit photometry was obtained in seven different bandpasses
$-$ $g^{\prime}$, $r^{\prime}$, $i^{\prime}$, blue-blocking, $I+z$,
$z^{\prime}$, and 0.85-1.55 $\mu$m $-$ covering a wavelength range from
$\sim$0.4 to 1.6 $\mu$m. Together with the TESS transit photometry, this
allowed us to check for a wavelength dependence of the transit depth, that
could indicate a blend with a stellar eclipsing binary either in the
background/foreground or bound to the target star. We found that the transit
depths in the individual bandpasses are in very good agreement and do not show
any chromatic dependence (besides the effect of stellar limb-darkening) within
the accuracy of the measurements (see Sect. 5.1.2 and Table 4).

###  4.3 Archival imaging

The high proper motion of LP 890-9 (333 mas $\mathrm{yr}^{-1}$, Gaia
Collaboration et al. 2021) makes it possible to investigate archival images
for a possible background object that could be blended with the target at its
current position (see, e.g., Bakos et al., 2006). We inspected POSS I/DSS
(Minkowski & Abell, 1963), POSS II/DSS2 (Reid et al., 1991), and Pan-STARRS1
(Chambers et al., 2016) images spanning 64 years with our recent observations.
None of these archival images show any source at the present-day target
location (see Fig. 8). Given the detection limits of these images, we can thus
rule out background sources brighter than $\sim$5 magnitudes below that of LP
890-9.

Table 3: Properties of the LP 890-9 planetary system based on our global
transit analysis (see Sect. 5.1.1).

Parameters | Values | Priors
---|---|---
Star | LP 890-9 |
Luminosity, $L_{\star}$ ($10^{-3}\>L_{\odot}$) | $1.438_{-0.037}^{+0.037}$ |  $\mathcal{N}$(1.441, 0.0382)
Effective temperature, $T_{\mathrm{eff}}$ (K) | $2871_{-45}^{+32}$ | $-$
Mass, $M_{\star}$ ($M_{\odot}$) | $0.118\pm 0.002$ |  $\mathcal{N}$(0.118, 0.0022)
Radius, $R_{\star}$ ($R_{\odot}$) | $0.1532_{-0.0024}^{+0.0048}$ | $-$
Density, $\rho_{\star}$ ($\rho_{\odot}$) | $32.9_{-3.0}^{+1.5}$ | $-$
Log surface gravity, log $g_{\star}$ (cgs) | $5.139_{-0.028}^{+0.013}$ | $-$
Quadratic limb-darkening coefficient $u_{1,\>g^{\prime}}$ | $0.813\pm 0.049$ |  $\mathcal{N}$(0.830, 0.0532)
Quadratic limb-darkening coefficient $u_{2,\>g^{\prime}}$ | $0.091_{-0.074}^{+0.062}$ |  $\mathcal{N}$(0.140, 0.0912)
Quadratic limb-darkening coefficient $u_{1,\>r^{\prime}}$ | $0.841\pm 0.047$ |  $\mathcal{N}$(0.847, 0.0512)
Quadratic limb-darkening coefficient $u_{2,\>r^{\prime}}$ | $0.062_{-0.070}^{+0.064}$ |  $\mathcal{N}$(0.086, 0.0912)
Quadratic limb-darkening coefficient $u_{1,\>i^{\prime}}$ | $0.531\pm 0.037$ |  $\mathcal{N}$(0.532, 0.0392)
Quadratic limb-darkening coefficient $u_{2,\>i^{\prime}}$ | $0.298_{-0.090}^{+0.084}$ |  $\mathcal{N}$(0.311, 0.1072)
Quadratic limb-darkening coefficient $u_{1,\>z^{\prime}}$ | $0.404_{-0.034}^{+0.033}$ |  $\mathcal{N}$(0.417, 0.0352)
Quadratic limb-darkening coefficient $u_{2,\>z^{\prime}}$ | $0.292_{-0.089}^{+0.086}$ |  $\mathcal{N}$(0.331, 0.1042)
Quadratic limb-darkening coefficient $u_{1,\>I+z}$ | $0.375\pm 0.027$ |  $\mathcal{N}$(0.384, 0.0282)
Quadratic limb-darkening coefficient $u_{2,\>I+z}$ | $0.243_{-0.076}^{+0.078}$ |  $\mathcal{N}$(0.303, 0.0892)
Quadratic limb-darkening coefficient $u_{1,\>\mathrm{blue-blocking}}$ | $0.416\pm 0.023$ |  $\mathcal{N}$(0.417, 0.0232)
Quadratic limb-darkening coefficient $u_{2,\>\mathrm{blue-blocking}}$ | $0.277_{-0.070}^{+0.069}$ |  $\mathcal{N}$(0.286, 0.0732)
Quadratic limb-darkening coefficient $u_{1,\>\mathrm{0.85-1.55\,\mu m}}$ | $0.238\pm 0.015$ |  $\mathcal{N}$(0.238, 0.0152)
Quadratic limb-darkening coefficient $u_{2,\>\mathrm{0.85-1.55\,\mu m}}$ | $0.203_{-0.061}^{+0.059}$ |  $\mathcal{N}$(0.212, 0.0602)
Quadratic limb-darkening coefficient $u_{1,\>\mathrm{TESS}}$ | $0.410\pm 0.026$ |  $\mathcal{N}$(0.409, 0.0262)
Quadratic limb-darkening coefficient $u_{2,\>\mathrm{TESS}}$ | $0.300_{-0.085}^{+0.081}$ |  $\mathcal{N}$(0.292, 0.0842)
Planets | b | c |
Transit depth, $\mathrm{d}F$ (ppm) | $6238_{-153}^{+168}$ | $6659_{-273}^{+282}$ | $-$
Transit impact parameter, $b$ ($R_{\star}$) | $0.15_{-0.10}^{+0.14}$ | $0.697_{-0.019}^{+0.024}$ | $-$
Orbital period, $P$ (days) | $2.7299025_{-0.0000040}^{+0.0000034}$ | $8.457463\pm 0.000024$ | $-$
Mid-transit time, $T_{0}$ ($\mathrm{BJD_{TDB}}-2\>450\>000$) | 9447.82637 $\pm$ 0.00014 | $9520.70598\pm 0.00031$ | $-$
Transit duration, $W$ (min) | $50.74_{-0.47}^{+0.51}$ | $57.56_{-0.91}^{+0.99}$ | $-$
Orbital inclination, $i_{\mathrm{p}}$ (deg) | $89.67_{-0.33}^{+0.22}$ | $89.287_{-0.047}^{+0.026}$ | $-$
Orbital semi-major axis, $a_{\mathrm{p}}$ (au) | $0.01875\pm 0.00010$ | $0.03984\pm 0.00022$ | $-$
Scale parameter, $a_{\mathrm{p}}/R_{\star}$ | $26.32_{-0.82}^{+0.39}$ | $55.94_{-1.74}^{+0.82}$ | $-$
Radius, $R_{\mathrm{p}}$ ($R_{\oplus}$) | $1.320_{-0.027}^{+0.053}$ | $1.367_{-0.039}^{+0.055}$ | $-$
Stellar irradiation, $S_{\mathrm{p}}$ ($S_{\oplus}$) | $4.09\pm 0.12$ | $0.906\pm 0.026$ | $-$
Equilibrium temperature,a $T_{\mathrm{eq}}$ (K) | $396\pm 3$ | $272\pm 2$ | $-$
RV semi-amplitude,b $K$ (m/s) | ¡ 25.1 | ¡ 33.0 | $-$
Mass,b $M_{\mathrm{p}}$ ($M_{\oplus}$) | ¡ 13.2 | ¡ 25.3 | $-$

Notes. For each parameter, we indicate the median of the posterior
distribution function, along with the 1-$\sigma$ credible intervals. For the
priors given in the last column, $\mathcal{N}(\mu,\sigma^{2})$ represents a
normal distribution of mean $\mu$ and variance $\sigma^{2}$. a The equilibrium
temperature corresponds to a case with null Bond albedo and an efficient heat
recirculation from the dayside to the nightside hemispheres of the planet. b
2$\sigma$ upper limits from our 2-planet RV fit (see Sect. 6).

###  4.4 Statistical validation

To fully vet the two planet candidates, we used the open-source software
package TRICERATOPS888https://github.com/stevengiacalone/triceratops
(Giacalone & Dressing, 2020; Giacalone et al., 2021), which uses a Bayesian
framework that incorporates prior knowledge of the target star, planet
occurrence rates, and stellar multiplicity to calculate the probability that
the transit signal is due to a planet transit or another astrophysical source.
To consider a planet as statistically validated, we require its False Positive
Probability (FPP), which is the sum of probabilities for all false positive
scenarios, to be less than 0.01 (1%). This condition was defined by Giacalone
et al. (2021) based on results obtained with TRICERATOPS for 68 TOIs (TESS
Objects of Interest) that were previously identified as either confirmed
planets or astrophysical false positives by TFOP using follow-up observations.

Using the phase-folded SSO $I+z$ transit light curve (which provides the
tightest photometric constraints) and the Zorro speckle imaging 5$\sigma$
contrast curve at 832 nm as inputs to TRICERATOPS, we found FPPs of 6.5
$\times$ $10^{-6}$ and 3.2 $\times$ $10^{-7}$ for the inner and outer
candidates, respectively. These values were obtained for each planet
individually, not accounting for the fact that they are both transiting in the
same system. Applying a ‘multiplicity boost’ to account for the a priori
higher likelihood of a candidate in a multi-transiting system to be a real
planet would allow to further reduce these FPPs, by a factor of $\sim$20–50
(Lissauer et al., 2012; Guerrero et al., 2021). In any case, these FPPs are
well below 1%, so we consider that the two transit signals correspond to
validated planets. Henceforth, we denote the inner one (TOI-4306.01) as LP
890-9 b and the second outer transiting planet (SPECULOOS-2 c) as LP 890-9 c.

Figure 9: Phase-folded detrended transit photometry of LP 890-9 b in each
observed bandpass. The unbinned data points are shown in grey, while the black
circles with error bars correspond to 10-min bins. The best-fit transit model
is shown in red, with a different limb darkening for each bandpass. Figure 10:
Phase-folded detrended transit photometry of LP 890-9 c in each observed
bandpass. The unbinned data points are shown in grey, while the black circles
with error bars correspond to 10-min bins. The best-fit transit model is shown
in red, with a different limb darkening for each bandpass. We note that the
MuSCAT3 $r^{\prime}$\- and $i^{\prime}$\- light curves show a possible hump
around mid-transit which could be related to spot crossing.