An M dwarf accompanied by a close-in giant orbiter with SPECULOOS
Abstract
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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 2023
- DOI:
- arXiv:
- arXiv:2308.02253
- Bibcode:
- 2023MNRAS.525L..98T
- Keywords:
-
- techniques: photometric;
- techniques: radial velocities;
- exoplanets;
- infrared: planetary systems;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication in MNRAS Letters