The unusual M-dwarf Warm Jupiter TOI-1899~b: Refinement of orbital and planetary parameters

TL;DR

This study refines the orbital and physical parameters of the rare Warm Jupiter exoplanet TOI-1899 b orbiting an M-dwarf, highlighting its unique position as the coolest known Jovian-sized planet around such stars and its potential for future atmospheric studies.

Contribution

The paper provides the first precise measurements of TOI-1899 b's orbit, mass, and radius, and emphasizes its significance for understanding gas giant formation and migration around M-dwarfs.

Findings

Refined orbital period to approximately 29.09 days.

Measured planet radius of about 0.99 Jupiter radii.

Determined planet mass to be around 0.67 Jupiter masses.

Abstract

TOI-1899 b is a rare exoplanet, a temperate Warm Jupiter orbiting an M-dwarf, first discovered by Ca\~nas et al. (2020) from a TESS single-transit event. Using new radial velocities (RVs) from the precision RV spectrographs HPF and NEID, along with additional TESS photometry and ground-based transit follow-up, we are able to derive a much more precise orbital period of $P = 29.090312_{-0.000035}^{+0.000036}$ d, along with a radius of $R_p = 0.99 \pm 0.03~R_J$. We have also improved the constraints on planet mass, $M_p = 0.67 \pm 0.04~M_J$, and eccentricity, which is consistent with a circular orbit at 2$\sigma$ ($e = 0.044_{-0.027}^{+0.029}$). TOI-1899 b occupies a unique region of parameter space as the coolest known ($T_{eq} \approx$ 380 K) Jovian-sized transiting planet around an M-dwarf; we show that it has great potential to provide clues regarding the formation and migration mechanisms of these rare gas giants through transmission spectroscopy with JWST as well as studies of tidal evolution.