TOI-7154b: A massive brown dwarf in a close, eccentric orbit around an old star

Star system: TOI-7154 A | Distance from the Sun: 975 light years

Astronomers discovered and characterized TOI-7154b, a massive brown dwarf orbiting close to its host star, TOI-7154. Initially flagged as a planet candidate by TESS, follow-up radial velocity measurements revealed its true sub-stellar nature. TOI-7154b is nearly as massive as the hydrogen-burning limit that separates brown dwarfs from very low-mass stars, but its radius is smaller than Jupiter’s. The brown dwarf orbits a metal-rich G-type star in an eccentric orbit, and the system is very old, as indicated by stellar models and galactic kinematics.

No additional companions were found in the system, and the persistent orbital eccentricity suggests that TOI-7154b likely formed through stellar-like fragmentation rather than planet-like processes. This system provides a valuable case for studying the transition between sub-stellar and stellar objects and the origins of brown dwarfs.

Key findings
- TOI-7154b is a massive brown dwarf near the hydrogen-burning limit.
- It orbits a metal-rich G-type star in a close, eccentric orbit.
- The system is very old, with no detected companions.
- The brown dwarf’s eccentricity points to a stellar-like formation origin.

Scientific study

TOI-7154b: A Close-in Massive Brown Dwarf in an Eccentric Orbit (external link)