A pair of warm giant planets near the 2:1 mean motion resonance around the K-dwarf star TOI-2202

TL;DR

This paper reports the discovery and analysis of a planetary system around the K-dwarf star TOI-2202, featuring two warm giant planets near the 2:1 mean motion resonance, with detailed observational and dynamical characterization.

Contribution

It presents the first detailed characterization of a system with two warm giant planets near the 2:1 MMR, combining transit, radial velocity, and TTV data.

Findings

Confirmed planetary nature of TOI-2202 b and c.

Detected strong TTVs indicating gravitational interaction.

System comprises a warm Jovian and Saturn-mass planet near 2:1 resonance.

Abstract

TOI-2202 b is a transiting warm Jovian-mass planet with an orbital period of P=11.91 days identified from the Full Frame Images data of five different sectors of the TESS mission. Ten TESS transits of TOI-2202 b combined with three follow-up light curves obtained with the CHAT robotic telescope show strong transit timing variations (TTVs) with an amplitude of about 1.2 hours. Radial velocity follow-up with FEROS, HARPS and PFS confirms the planetary nature of the transiting candidate (a$_{\rm b}$ = 0.096 $\pm$ 0.002 au, m$_{\rm b}$ = 0.98 $\pm$ 0.06 M$_{\rm Jup}$), and dynamical analysis of RVs, transit data, and TTVs points to an outer Saturn-mass companion (a$_{\rm c}$ = 0.155 $\pm$ 0.003 au, m$_{\rm c}$= $0.37 \pm 0.10$ M$_{\rm Jup}$) near the 2:1 mean motion resonance. Our stellar modeling indicates that TOI-2202 is an early K-type star with a mass of 0.82 M$_\odot$, a radius of 0.79 R$_\odot$, and solar-like metallicity. The TOI-2202 system is very interesting because of the two warm Jovian-mass planets near the 2:1 MMR, which is a rare configuration, and their formation and dynamical evolution are still not well understood.