TESS Discovery of a Transiting Super-Earth in the $\pi$ Mensae System

TL;DR

This paper reports the discovery of a transiting super-Earth in the $$ Mensae system using TESS data, confirmed by radial velocities, with implications for future atmospheric and dynamical studies.

Contribution

First detection of a transiting super-Earth around $$ Mensae using TESS, combining photometry and radial velocities for confirmation and characterization.

Findings

Discovered a 2.04 R super-Earth with a 6.27-day orbit.

Confirmed planetary mass of 4.82 M via radial velocities.

Star's brightness enables detailed follow-up observations.

Abstract

We report the detection of a transiting planet around $\pi$ Mensae (HD 39091), using data from the Transiting Exoplanet Survey Satellite (TESS). The solar-type host star is unusually bright (V=5.7) and was already known to host a Jovian planet on a highly eccentric, 5.7-year orbit. The newly discovered planet has a size of $2.04\pm 0.05$ $R_\oplus$ and an orbital period of 6.27 days. Radial-velocity data from the HARPS and AAT/UCLES archives also displays a 6.27-day periodicity, confirming the existence of the planet and leading to a mass determination of $4.82\pm 0.85$ $M_\oplus$. The star's proximity and brightness will facilitate further investigations, such as atmospheric spectroscopy, asteroseismology, the Rossiter--McLaughlin effect, astrometry, and direct imaging.