TRAPPIST-1b
TRAPPIST-1b, also designated as 2MASS J23062928-0502285 b, is a mainly rocky exoplanet orbiting around the ultra-cool dwarf star TRAPPIST-1, located 40.7 light-years (12.5 parsecs) away from Earth in the constellation of Aquarius. The planet was detected using the transit method, where a planet dims the host star's light as it passes in front of it. It was first announced on May 2, 2016, and later studies were able to refine its physical parameters.
Earth and TRAPPIST-1b compared | |
| Discovery | |
|---|---|
| Discovered by | Michaël Gillon et al. |
| Discovery site | TRAPPIST |
| Discovery date | May 2, 2016 |
| Transit | |
| Orbital characteristics | |
| 0.01154 ± 0.00010 AU (1,726,000 ± 15,000 km) | |
| Eccentricity | 0.00622±0.00304 |
| 1.510826 ± 0.000006 d (36.25982 ± 0.00014 h) | |
| Inclination | 89.728°±0.165° |
| 336.86°±34.24° | |
| Star | TRAPPIST-1 |
| Physical characteristics | |
Mean radius | 1.116+0.014 −0.012 R🜨 |
| Mass | 1.374±0.069 M🜨 |
Mean density | 5.425+0.265 −0.272 g/cm3 |
| 1.102±0.052 g 10.80±0.51 m/s2 | |
| Temperature | 397.6±3.8 K (124.5 °C; 256.0 °F, equilibrium) 503+26 −27 K (230 °C; 446 °F, surface) |
| Atmosphere | |
| Composition by volume | None or extremely thin |
The planet is about 37% more massive than Earth and about 39% larger in volume; thus its density is very similar. It is the innermost of seven planets orbiting TRAPPIST-1, all of which are terrestrial, but is too close to its star to be in the habitable zone. Observations by the James Webb Space Telescope announced in 2023 suggest that it does not have any significant atmosphere. Its albedo is very low, making it dark in color.