Discovery and Characterization of an Eccentric, Warm Saturn Transiting the Solar Analog TOI-4994

Abstract

We present the detection and characterization of TOI-4994b (TIC 277128619b), a warm Saturn-sized planet discovered by the NASA Transiting Exoplanet Survey Satellite. TOI-4994b transits a G-type star ( V = 12.6 mag) with a mass, radius, and effective temperature of ${M}_{\star }=1.00{5}_{-0.061}^{+0.064}{M}_{\odot }$ , ${R}_{\star }=1.05{5}_{-0.037}^{+0.040}{R}_{\odot }$ , and T _eff = 5640 ± 110 K. We obtained follow-up ground-based photometry from the Las Cumbres Observatory and the Antarctic Search for Transiting ExoPlanets telescopes, and we confirmed the planetary nature of TOI-4994b with multiple radial velocity observations from the Planet Finder Spectrograph, CHIRON, High Accuracy Radial velocity Planet Searcher, Fiber-fed Extended Range Optical Spectrograph, and CORALIE instruments. From a global fit to the photometry and radial velocities, we determine that TOI-4994b is in a 21.5 day eccentric orbit ( e = 0.32 ± 0.04) and has a mass of ${M}_{P}=0.28{0}_{-0.034}^{+0.037}{M}_{J}$ , a radius of ${R}_{P}=0.76{2}_{-0.027}^{+0.030}{R}_{J}$ , and a Saturn-like bulk density of ${\rho }_{p}=0.7{8}_{-0.14}^{+0.16}\,{\rm{g}}\,{\mathrm{cm}}^{-3}$ . We find that TOI-4994 is a potentially viable candidate for follow-up stellar obliquity measurements. TOI-4994b joins the small sample of warm Saturn analogs and thus sheds light on our understanding of these rare and unique worlds.

Keywords

• Exoplanets
• Extrasolar gaseous planets