TOI-544 b: a potential water-world inside the radius valley in a two-planet system
Journal article, 2024
We report on the precise radial velocity follow-up of TOI-544 (HD 290498),ã bright K star ( V = 10.8), which hostsã small transiting planet recently disco v ered by the Trãnsiting Exoplanet Survey Satellite (TESS) . We collected 122 high-resolution High Accuracy Radial velocity Planet Searcher (HARPS)ãnd HARPS-N spectra to spectroscopically confirm the transiting planetãnd measure its mass. The nearly 3-yr baseline of our follow-upãllowed us to unveil the presence ofãnãdditional, non-transiting, longer-period companion planet. We derivedã radiusãnd mass for the inner planet, TOI-544 b, of 2.018 ±0.076 R⊙and 2.89 ±0.48 M⊙, respectively, which givesã bulk density of 1 . 93 + 0 . 30 -0 . 25 g cm -3 . TOI-544 c hasã minimum mass of 21.5 ±2.0 M⊙and orbital period of 50.1 ±0.2 d. The low density of planet-b implies that it has eitherãn Earth-like rocky core withã hydrogenãtmosphere, orã composition which harboursã significant fraction of water. The composition interpretation is degenerate depending on the specific choice of planet interior models used. Additionally, TOI-544 b hasãn orbital period of 1.55 dãnd equilibrium temperature of 999 ±14 K, placing it within the predicted location of the radius valley, where few planetsãre expected. TOI-544 b isã top target for futureãtmospheric observations, for example with JWST , which would enable better constraints of the planet composition.
techniques: radial velocities
planetsãnd satellites: composition
planetsãnd satellites: detection
Author
H. L.M. Osborne
European Southern Observatory (ESO)
University College London (UCL)
Vincent Van Eylen
University College London (UCL)
E. Goffo
Thüringer Landessternwarte Tautenburg
University of Turin
D. Gandolfi
University of Turin
G. Nowak
Nicolaus Copernicus University
University of La Laguna
Instituto de Astrofísica de Canarias
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
J.H. Livingston
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
National Institutes of Natural Sciences
A. Weeks
University College London (UCL)
Enric Palle
University of La Laguna
Instituto de Astrofísica de Canarias
R. Luque
University of Chicago
Coel Hellier
Keele University
Ilaria Carleo
Instituto de Astrofísica de Canarias
S. Redfield
Wesleyan University
T. Hirano
The Graduate University for Advanced Studies (SOKENDAI)
National Institutes of Natural Sciences
National Astronomical Observatory of Japan
M. Garbaccio Gili
University of Turin
Javier Alarcon
European Southern Observatory Santiago
O. Barragán
University of Oxford
Núria Casasayas-Barris
Instituto de Astrofísica de Canarias
University of La Laguna
Matías R. Díaz
Las Campanas Observatory
M. Esposito
Thüringer Landessternwarte Tautenburg
E. Knudstrup
Aarhus University
James S. Jenkins
Institute of Astrophysics of Andalusia (IAA)
Centro de Astrofísica y Tecnologías Afines (CATA),
F. Murgas
University of La Laguna
Instituto de Astrofísica de Canarias
J. Orell-Miquel
University of La Laguna
Instituto de Astrofísica de Canarias
F. Rodler
European Southern Observatory Santiago
L. M. Serrano
University of Turin
M. Stangret
Instituto de Astrofísica de Canarias
University of La Laguna
S. H. Albrecht
Aarhus University
A. Alqasim
University College London (UCL)
William D. Cochran
The University of Texas at Austin
H. Deeg
University of Chicago
Diego Portales University
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Leiden University
A. Hatzes
Thüringer Landessternwarte Tautenburg
Judith Korth
Lund University
K. W.F. Lam
German Aerospace Center (DLR)
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 527 4 11138-11157Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1093/mnras/stad3837