The TESS-Keck Survey. XXII. A sub-Neptune Orbiting TOI-1437

TL;DR

This paper reports the discovery and detailed characterization of TOI-1437 b, a sub-Neptune exoplanet orbiting a near-Solar star, using TESS photometry and radial velocity follow-up, contributing valuable data to understanding sub-Neptune formation.

Contribution

It presents the first combined photometric and radial velocity analysis of TOI-1437 b, providing precise mass and radius measurements for a rare sub-Neptune orbiting a solar-mass star.

Findings

Planet radius: 2.24 +/- 0.23 Rearth

Planet mass: 9.6 +/- 3.9 Mearth

One of ~50 transiting sub-Neptunes with RV mass measurement

Abstract

Exoplanet discoveries have revealed a dramatic diversity of planet sizes across a vast array of orbital architectures. Sub-Neptunes are of particular interest; due to their absence in our own solar system, we rely on demographics of exoplanets to better understand their bulk composition and formation scenarios. Here, we present the discovery and characterization of TOI-1437 b, a sub-Neptune with a 18.84 day orbit around a near-Solar analog (Mstar = 1.10 +/- 0.10 Msun, Rstar = 1.17 +/- 0.12 Rsun). The planet was detected using photometric data from the Transiting Exoplanet Survey Satellite (TESS) mission and radial velocity follow-up observations were carried out as a part of the TESS-Keck Survey (TKS) using both the HIRES instrument at Keck Observatory and the Levy Spectrograph on the Automated Planet Finder (APF) telescope. A combined analysis of these data reveal a planet radius of Rp = 2.24 +/- 0.23 Rearth and a mass measurement of Mp = 9.6 +/- 3.9 Mearth). TOI-1437 b is one of few (~50) known transiting sub-Neptunes orbiting a solar-mass star that has a radial velocity mass measurement. As the formation pathway of these worlds remains an unanswered question, the precise mass characterization of TOI-1437 b may provide further insight into this class of planet.