LHS 1478 b
| Discovery | |
|---|---|
| Discovered by | M. G. Soto, et al. |
| Discovery site | TESS |
| Discovery date | February 2021 |
| Transit | |
| Designations | |
| TOI-1640 b | |
| Orbital characteristics | |
| 0.01872±0.00015 AU | |
| Eccentricity | 0.038+0.16 −0.033 |
| 1.94953941(50) d | |
| Inclination | 87.69°+0.41° −0.22° |
| 86.2°+4.5° −130° | |
| Semi-amplitude | 3.12±0.62 m/s |
| Star | LHS 1478 |
| Physical characteristics | |
| 1.174±0.055 R🜨 | |
| Mass | 2.27±0.45 M🜨 |
Mean density | 7.7+2.0 −1.7 g/cm3 |
| Temperature | 597.3+11 −7.0 K (324.1 °C; 615.5 °F, equilibrium) |
LHS 1478 b is a super-Earth exoplanet orbiting around LHS 1478, a red dwarf star located 59.4 light-years from Earth in the constellation of Cassiopeia. It orbits at a distance of 0.018 AU from the star with a inclination of 87° to the plane of the sky. It takes LHS 1478b roughly 1.9 days to complete an orbit around the star.
It has a mass of 2.27 Earths and a radius of 1.17 Earths. It has a bulk density of 7.7 g cm−3 making it consistent with a terrestrial planet with a composition mainly of Fe (~30%) and MgSiO3(~70%). It is classed as a hot super-Earth with an equilibrium temperature of 585 Kelvin receiving 21 times more energy from its star than Earth does from the Sun. This makes it impossible for water to remain a liquid on the surface suggesting that LHS 1478b may have a Venus-like atmosphere.
The star it orbits around is a fairly inactive red dwarf star allowing for favorable conditions for spectroscopic studies with the James Webb Space Telescope (JWST). This places LHS 1478b with a family of small rocky planets (GJ 357 b, GJ 1132 b and GJ 486 b) where meaningful and realistic measurements with JWST can be taken. JWST observations disfavor the possibility of a low-albedo bare rock, suggesting that the planet either has an atmosphere or a high albedo without an atmosphere.