Authors:
Osborne, H. L. M.;Van Eylen, V.;Goffo, E.;Gandolfi, D.;Nowak, G.;Persson, C. M.;Livingston, J.;Weeks, A.;Pallé, E.;Luque, R.;Hellier, C.;Carleo, I.;Redfield, S.;Hirano, T.;Gili, M. Garbaccio;Alarcon, J.;Barragán, O.;Casasayas-Barris, N.;Díaz, M. R.;Esposito, M.;Jenkins, J. S.;Knudstrup, E.;Murgas, F.;Orell-Miquel, J.;Rodler, F.;Serrano, L.;Stangret, M.;Albrecht, S. H.;Alqasim, A.;Cochran, W. D.;Deeg, H. J.;Fridlund, M.;Hatzes, A.;Korth, J.;Lam, K. W. F.
Journal:
Monthly Notices of the Royal Astronomical Society
Abstract:
We report on the precise radial velocity follow-up of TOI-544 (HD 290498), a bright K star (V=10.8), which hosts a small transiting planet recently discovered by the Transiting Exoplanet Survey Satellite (TESS). We collected 122 high-resolution HARPS and HARPS-N spectra to spectroscopically confirm the transiting planet and measure its mass. The nearly 3-year baseline of our follow-up allowed us to unveil the presence of an additional, non-transiting, longer-period companion planet. We derived a radius and mass for the inner planet, TOI-544 b, of 2.018 ± 0.076 R<SUB>⊕</SUB> and 2.89 ± 0.48 M<SUB>⊕</SUB> respectively, which gives a bulk density of $1.93^{+0.30}_{-0.25}$ g cm<SUP>-3</SUP>. TOI-544 c has a minimum mass of 21.5 ± 2.0 M<SUB>⊕</SUB> and orbital period of 50.1 ± 0.2 days. The low density of planet-b implies that it has either an Earth-like rocky core with a hydrogen atmosphere, or a composition which harbours a significant fraction of water. The composition interpretation is degenerate depending on the specific choice of planet interior models used. Additionally, TOI-544 b has an orbital period of 1.55 days and equilibrium temperature of 999 ± 14 K, placing it within the predicted location of the radius valley, where few planets are expected. TOI-544 b is a top target for future atmospheric observations, for example with JWST, which would enable better constraints of the planet composition.
URL:
https://ui.adsabs.harvard.edu/#abs/2024MNRAS.52711138O/abstract
Keywords:
exoplanets;techniques: radial velocities;planets and satellites: composition;planets and satellites: detection;Astrophysics - Earth and Planetary Astrophysics