A transiting warm giant planet around the young active star TOI-201

TL;DR

This paper reports the discovery and detailed characterization of TOI-201 b, a warm, eccentric giant planet orbiting a young active star, providing insights into planetary formation and evolution.

Contribution

It presents the first confirmation and detailed parameters of a warm giant planet around a young star using combined space-based and ground-based observations.

Findings

TOI-201 b has a mass of approximately 0.42 Jupiter masses.

The planet's radius is about 1.008 Jupiter radii.

It has an orbital eccentricity of 0.28.

Abstract

We present the confirmation of the eccentric warm giant planet TOI-201 b, first identified as a candidate in \textit{TESS} photometry (Sectors 1-8, 10-13, and 27-28) and confirmed using ground-based photometry from NGTS and radial velocities from FEROS, HARPS, CORALIE, and \textsc{Minerva}-Australis. TOI-201 b orbits a young ($\mathrm{0.87^{+0.46}_{-0.49} \, Gyr}$) and bright(V=9.07 mag) F-type star with a $\mathrm{52.9781 \, d}$ period. The planet has a mass of $\mathrm{0.42^{+0.05}_{-0.03}\, M_J}$, a radius of $\mathrm{1.008^{+0.012}_{-0.015}\, R_J}$, and an orbital eccentricity of $0.28^{+0.06}_{-0.09}$; it appears to still be undergoing fairly rapid cooling, as expected given the youth of the host star. The star also shows long-term variability in both the radial velocities and several activity indicators, which we attribute to stellar activity. The discovery and characterization of warm giant planets such as TOI-201 b is important for constraining formation and evolution theories for giant planets.