LP 890-9

LP 890-9, also known as SPECULOOS-2 or TOI-4306, is a high proper motion red dwarf star located 105 ly away from the Solar System in the constellation of Eridanus. The star has 12% the mass and 15% the radius of the Sun, and a temperature of 2871 K. It is extremely faint and, with an apparent magnitude of 18, is the faintest star with exoplanets discovered by the Transiting Exoplanet Survey Satellite.

Planetary system
In 2022, two exoplanets were discovered in orbit around this star. The first planet, LP 890-9 b, was initially identified using TESS. Further observations using SPECULOOS confirmed this planet and discovered a second planet, LP 890-9 c. Both planets are likely terrestrial planets, somewhat larger than Earth. The outer planet LP 890-9 c orbits within the habitable zone, and is a favorable target for atmospheric characterization using JWST.

LP 890-9 c orbits near the inner edge of the conservative habitable zone, and models differ as to whether the planet is more likely to resemble Earth or Venus. Spectra from JWST should make it possible to distinguish between these two scenarios. The planet is tidally locked. While the planet's location in the habitable zone suggests a strong possibility of an Earth-like atmosphere and climate, the planet's large size may count against its habitability. In addition, the planet is close enough to its star that powerful radiation may reduce its habitability.