TOI-837b is a Young Saturn-sized Exoplanet with a Massive 70 $M_{\oplus}$ Core

TL;DR

This paper reports the discovery and detailed characterization of TOI-837b, a young Saturn-sized exoplanet with a massive core, challenging current formation theories and highlighting the potential of future JWST observations.

Contribution

It provides the first detailed analysis of a young exoplanet with a large core, combining photometry and spectroscopy to determine its properties and implications for planet formation models.

Findings

TOI-837b has a radius of 0.82 R_J and a mass of 0.39 M_J.

The planet's core is estimated at about 70 M_E, making up 60% of its total mass.

The results challenge existing theories of core formation in young giant planets.

Abstract

We present an exhaustive photometric and spectroscopic analysis of TOI-837, a F9/G0 35 Myr young star, hosting a transiting exoplanet, TOI-837b, with an orbital period of 8.32d. Utilising data from TESS and ground-based observations, we determine a planetary radius of 0.82 R_J for TOI-837b. Through detailed HARPS spectroscopic time series analysis, we derive a Doppler semi-amplitude of 35 m/s, corresponding to a planetary mass of 0.39 M_J. The derived planetary properties suggest a substantial core of approximately 70 M_E, constituting about 60% of the planet's total mass. This finding poses a significant challenge to existing theoretical models of core formation. We propose that future atmospheric observations with JWST could provide insights into resolving ambiguities of TOI-837b, offering new perspectives on its composition, formation, and evolution.