LHS 475

LHS 475 is a red dwarf star located 40.7 ly away from the Solar System in the constellation of Octans. It hosts one known exoplanet.

Planetary system


The exoplanet LHS 475 b was initially found in transit data from TESS, and its confirmation using the NIRSpec instrument of the James Webb Space Telescope, which also observed its transmission spectrum, was published in January 2023. Another independent confirmation of the planet was published on arXiv in April 2023, and a year later accepted to the Astronomical Journal.

The JWST data is consistent with a featureless spectrum, as would be expected of a planet with no atmosphere, but is also consistent with some types of atmosphere, such as a thin carbon dioxide-dominated atmosphere like that of Mars, or an atmosphere obscured by a thick cloud deck such as that of Venus. Other atmospheric compositions, such as a methane-dominated atmosphere, are ruled out by this spectrum.

LHS 475 b is close in size to Earth, at 99% its diameter, but is much hotter, with an equilibrium temperature of 586 K. Assuming the planet has little to no atmosphere, its dayside temperature is estimated at 748 K. The planet completes an orbit around its star in just two days and is likely tidally locked.