The Discovery and Follow-up of Four Transiting Short-period Sub-Neptunes Orbiting M Dwarfs
Journal article, 2024
Sub-Neptunes with radii of 2-3 R ⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of R p = 2.740 − 0.079 + 0.082 R ⊕ , 2.769 − 0.068 + 0.073 R ⊕ , 2.120 ± 0.067 R ⊕, and 2.830 − 0.066 + 0.068 R ⊕ and orbital periods of P = 8.02, 8.11, 5.80, and 3.08 days, respectively. Doppler monitoring with the Subaru/InfraRed Doppler instrument led to 2σ upper limits on the masses of <19.1 M ⊕, <19.5 M ⊕, <6.8 M ⊕, and <15.6 M ⊕ for TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b, respectively. The mass-radius relationship of these four sub-Neptunes testifies to the existence of volatile material in their interiors. These four sub-Neptunes, which are located above the so-called “radius valley,” are likely to retain a significant atmosphere and/or an icy mantle on the core, such as a water world. We find that at least three of the four sub-Neptunes (TOI-782 b, TOI-2120 b, and TOI-2406 b), orbiting M dwarfs older than 1 Gyr, are likely to have eccentricities of e ∼ 0.2-0.3. The fact that tidal circularization of their orbits is not achieved over 1 Gyr suggests inefficient tidal dissipation in their interiors.
Author
Yasunori Hori
National Institutes of Natural Sciences
A. Fukui
University of Tokyo
T. Hirano
National Institutes of Natural Sciences
Norio Narita
National Institutes of Natural Sciences
Jerome P. De Leon
University of Tokyo
Hiroyuki Tako Ishikawa
Western University
Joel D. Hartman
Princeton University
Giuseppe Morello
Instituto de Astrofísica de Canarias
N. Abreu Garcia
Instituto de Astrofísica de Canarias
Leticia Álvarez Hernández
Instituto de Astrofísica de Canarias
V. J. S. Bejar
Instituto de Astrofísica de Canarias
Yéssica Calatayud-Borras
Instituto de Astrofísica de Canarias
Ilaria Carleo
Instituto de Astrofísica de Canarias
Gareb Enoc
Instituto de Astrofísica de Canarias
E. Esparza-Borges
Instituto de Astrofísica de Canarias
Izuru Fukuda
University of Tokyo
D. Galán
Instituto de Astrofísica de Canarias
S. Geraldía-González
Instituto de Astrofísica de Canarias
Y. Hayashi
University of Tokyo
Masahiro Ikoma
National Astronomical Observatory of Japan
Kai Ikuta
University of Tokyo
Keisuke Isogai
University of Tokyo
T. Kagetani
University of Tokyo
Yugo Kawai
University of Tokyo
Kiyoe Kawauchi
College of Life Sciences
Tadahiro Kimura
National Astronomical Observatory of Japan
T. Kodama
Tokyo Institute of Technology
Judith Korth
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Nobuhiko Kusakabe
National Institutes of Natural Sciences
A. Laza-Ramos
Universitat de Valencia
J.H. Livingston
National Institutes of Natural Sciences
R. Luque
University of Chicago
Kohei Miyakawa
National Astronomical Observatory of Japan
Mayuko Mori
National Institutes of Natural Sciences
F. Murgas
Instituto de Astrofísica de Canarias
J. Orell-Miquel
Instituto de Astrofísica de Canarias
Enric Palle
Instituto de Astrofísica de Canarias
H. Parviainen
Instituto de Astrofísica de Canarias
A. Peláez-Torres
Instituto de Astrofísica de Canarias
M. Puig-Subirà
Instituto de Astrofísica de Canarias
M. Sánchez-Benavente
Instituto de Astrofísica de Canarias
Paula Sosa-Guillén
Instituto de Astrofísica de Canarias
M. Stangret
Istituto nazionale di astrofisica (INAF)
Y. Terada
Academia Sinica
Sara Muñoz Torres
Instituto de Astrofísica de Canarias
Noriharu Watanabe
University of Tokyo
Gaspar Á. Bakos
Princeton University
Khalid Barkaoui
Instituto de Astrofísica de Canarias
C. Beichman
National Aeronautics and Space Administration (NASA)
Z. Benkhaldoun
Faculté des Sciences Semlalia
A. W. Boyle
California Institute of Technology (Caltech)
D. R. Ciardi
California Institute of Technology (Caltech)
Catherine A. Clark
National Aeronautics and Space Administration (NASA)
Karen A. Collins
Harvard-Smithsonian Center for Astrophysics
Kevin I. Collins
George Mason University
D. Conti
American Association of Variable Star Observers
I. J.M. Crossfield
University of Kansas
M.E. Everett
NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab)
Elise Furlan
National Aeronautics and Space Administration (NASA)
M. Ghachoui
University of Liège
Michaël Gillon
University of Liège
Erica J. Gonzales
University of California at Santa Cruz
Jesus Higuera
NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab)
Keith Horne
SUPA
S.B. Howell
National Aeronautics and Space Administration (NASA)
Emmanuel Jehin
University of Liège
Kathryn V. Lester
National Aeronautics and Space Administration (NASA)
M. B. Lund
National Aeronautics and Space Administration (NASA)
Rachel A. Matson
US Naval Observatory
Elisabeth Matthews
Max Planck Society
Francisco J. Pozuelos
Spanish National Research Council (CSIC)
B. S. Safonov
Moscow State University
Joshua E. Schlieder
National Aeronautics and Space Administration (NASA)
R. Schwarz
Harvard-Smithsonian Center for Astrophysics
Ramotholo Sefako
South African Astronomical Observatory
G. Srdoc
Kotizarovci Observatory
I. A. Strakhov
Moscow State University
M. Timmermans
University of Liège
William C. Waalkes
University of Colorado at Boulder
C. Ziegler
Stephen F. Austin State University
D. Charbonneau
Harvard-Smithsonian Center for Astrophysics
Zahra Essack
University of New Mexico
N. Guerrero
Massachusetts Institute of Technology (MIT)
University of Florida
Hiroki Harakawa
National Astronomical Observatory of Japan
Christina Hedges
National Aeronautics and Space Administration (NASA)
Masato Ishizuka
University of Tokyo
Jon M. Jenkins
National Aeronautics and Space Administration (NASA)
Mihoko Konishi
Oita University
Takayuki Kotani
National Institutes of Natural Sciences
T. Kudo
National Astronomical Observatory of Japan
Takashi Kurokawa
National Astronomical Observatory of Japan
M. Kuzuhara
National Institutes of Natural Sciences
Jun Nishikawa
National Institutes of Natural Sciences
Masashi Omiya
National Institutes of Natural Sciences
George R. Ricker
Massachusetts Institute of Technology (MIT)
S. Seager
Massachusetts Institute of Technology (MIT)
Takuma Serizawa
National Astronomical Observatory of Japan
S. Striegel
SETI Institute
Motohide Tamura
National Institutes of Natural Sciences
Akitoshi Ueda
National Institutes of Natural Sciences
Roland K. Vanderspek
Massachusetts Institute of Technology (MIT)
Sébastien Vievard
National Astronomical Observatory of Japan
J. N. Winn
Princeton University
Astronomical Journal
0004-6256 (ISSN) 1538-3881 (eISSN)
Vol. 167 6 289Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Condensed Matter Physics
DOI
10.3847/1538-3881/ad4115