An M dwarf accompanied by a close-in giant orbiter with SPECULOOS

Publication date: 
Main author: 
Triaud, Amaury H. M. J.
IAA authors: 
Pozuelos, Francisco J.
Triaud, Amaury H. M. J.;Dransfield, Georgina;Kagetani, Taiki;Timmermans, Mathilde;Narita, Norio;Barkaoui, Khalid;Hirano, Teruyuki;Rackham, Benjamin V.;Mori, Mayuko;Baycroft, Thomas;Benkhaldoun, Zouhair;Burgasser, Adam J.;Caldwell, Douglas A.;Collins, Karen A.;Davis, Yasmin T.;Delrez, Laetitia;Demory, Brice-Oliver;Ducrot, Elsa;Fukui, Akihiko;Muñoz, Clàudia Jano;Jehin, Emmanuël;García, Lionel J.;Ghachoui, Mourad;Gillon, Michaël;Chew, Yilen Gómez Maqueo;Hooton, Matthew J.;Ikoma, Masahiro;Kawauchi, Kiyoe;Kotani, Takayuki;Levine, Alan M.;Pallé, Enric;Pedersen, Peter P.;Pozuelos, Francisco J.;Queloz, Didier;Scutt, Owen J.;Seager, Sara;Sebastian, Daniel;Tamura, Motohide;Thompson, Samantha;Watanabe, Noriharu;de Wit, Julien;Winn, Joshua N.;Zúñiga-Fernández, Sebastián
Monthly Notices of the Royal Astronomical Society
Publication type: 
In the last decade, a dozen close-in giant planets have been discovered orbiting stars with spectral types ranging from M0 to M4, a mystery since known formation pathways do not predict the existence of such systems. Here, we confirm TOI-4860 b, a Jupiter-sized planet orbiting an M4.5 host, a star at the transition between fully and partially convective interiors. First identified with TESS data, we validate the transiting companion's planetary nature through multicolour photometry from the TRAPPIST-South/North, SPECULOOS, and MuSCAT3 facilities. Our analysis yields a radius of $0.76\pm 0.02~\rm R_{Jup}$ for the planet, a mass of $0.34~\rm M_\odot$ for the star, and an orbital period of $1.52~\rm d$. Using the newly commissioned SPIRIT InGaAs camera at the SPECULOOS-South Observatory, we collect infrared photometry in zYJ that spans the time of secondary eclipse. These observations do not detect a secondary eclipse, placing an upper limit on the brightness of the companion. The planetary nature of the companion is further confirmed through high-resolution spectroscopy obtained with the IRD spectrograph at Subaru Telescope, from which we measure a mass of $0.67\pm 0.14~\rm M_{Jup}$. Based on its overall density, TOI-4860 b appears to be rich in heavy elements, like its host star.
ADS Bibcode: 
techniques: photometric;techniques: radial velocities;exoplanets;infrared: planetary systems;Astrophysics - Earth and Planetary Astrophysics;Astrophysics - Solar and Stellar Astrophysics