LHS 475 b

Astrophysical Synthesis & Habitability Characterization

LHS 475 b is a confirmed terrestrial exoplanet orbiting the star LHS 475, located approximately 40.7 light-years (12.48 parsecs) from the Solar System. First announced in 2023 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1061% across the stellar disk), this world measures 0.991 Earth radii and has a measured mass of 0.941 Earth masses. Combining its mass and radius yields a mean bulk density of 5.33 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.96 g⊕ (9.41 m/s²), and an escape velocity of 10.9 km/s.

In its orbital architecture around LHS 475, LHS 475 b completes one full revolution every 2.029 Earth days at a semi-major axis of 0.02037 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 109.2 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 586 K (+313°C / +595°F) and receiving 20.80 S⊕ (~28,309 W/m²), LHS 475 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star LHS 475 is classified as a low-mass red dwarf of spectral type M3.5 V with an effective photospheric temperature of 3,300 K, a radius of 0.2789 R☉, a mass of 0.262 M☉, an estimated bolometric luminosity of 0.00828 L☉. From Earth, LHS 475 shines at apparent V-band magnitude 13 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

Discovery Facility: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).