L 363-38 b: a planet newly discovered with ESPRESSO orbiting a nearby M dwarf star

TL;DR

This paper reports the discovery of a new exoplanet, L 363-38 b, orbiting a nearby M dwarf star using ESPRESSO radial velocity measurements, highlighting the potential of current instruments for target identification before next-generation telescopes.

Contribution

It presents the first detection of a planet around L 363-38 using ESPRESSO, demonstrating the effectiveness of blind RV searches in the solar neighborhood.

Findings

L 363-38 b has a minimum mass of 4.67 Earth masses.

The planet orbits every 8.78 days at 0.048 AU.

The planet's equilibrium temperature is approximately 330K.

Abstract

Context. Planets around stars in the solar neighbourhood will be prime targets for characterisation with upcoming large space- and ground-based facilities. Since large-scale exoplanet searches will not be feasible with such telescopes, it is crucial to use currently available data and instruments to find possible target planets before next generation facilities come online. Aims. We aim at detecting new extrasolar planets around stars in the solar neighbourhood by blind radial velocity (RV) search with ESPRESSO. Our target sample consist of nearby stars (d < 11 pc) with little (< 10) or no previous RV measurements. Methods. We use 31 radial velocity measurements obtained with ESPRESSO at the VLT between December 2020 and February 2022 of the nearby M dwarf star (M_star = 0.21 M_sun, d = 10.23 pc) L 363-38 to derive the orbital parameters of the newly discovered planet. In addition, we use TESS photometry and archival VLT/NaCo high contrast imaging data to put further constraints on the orbit inclination and the possible planetary system architecture around L 363-38. Results. We present the detection of a new extrasolar planet orbiting the nearby M dwarf star L 363-38. L 363-38 b is a planet with minimum mass mp sin(i) = 4.67+/-0.43 M_Earth orbiting its star with a period P = 8.781+/-0.007 d, corresponding to a semi-major axis a = 0.048+/-0.006 AU, which is well inside the inner edge of the habitable zone. We further estimate a minimum radius rp sin(i) = 1.55 - 2.75 R_Earth and an equilibrium temperature Teq = 330K.