TRAPPIST-1e
TRAPPIST-1e, also known as 2MASS J23062928-0502285 e, is a rocky, almost earth-size exoplanet orbiting within the habitable zone around the ultracool dwarf star TRAPPIST-1 about 40 light-years (12 parsecs) away from Earth in the constellation of Aquarius. Astronomers found the exoplanet by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured.
 Artist's impression of TRAPPIST-1e from 2018, showed here as a tidally locked planet with a liquid ocean. The actual appearance of the exoplanet is right now unknown, but based on its density, it is likely not completely covered in water. | |
| Discovery | |
|---|---|
| Discovered by | Spitzer Space Telescope |
| Discovery date | 22 February 2017 |
Detection method | Transit |
| Orbital characteristics | |
| Apastron | 0.0294322±0.000017 AU |
| Periastron | 0.0291335±0.000017 AU |
| 0.02928285 ± 3.4e-07[1] AU | |
| Eccentricity | 0.00510±0.00058[1] |
| 6.099043 ± 0.000015[2] d | |
| Inclination | 89.860+0.10 −0.12[1] |
| Star | TRAPPIST-1[3] |
| Physical characteristics | |
Mean radius | 0.910+0.027 −0.026[1] REarth |
| Mass | 0.772+0.075 −0.079[1] M🜨 |
Mean density | 5.65+0.39 −0.42 g cm−3 |
| 0.930+0.063 −0.068[1] g | |
| Temperature | Teq: 246.1 ± 3.5 K (−27.05 ± 3.50 °C; −16.69 ± 6.30 °F)[2] |
The exoplanet was one of seven new exoplanets discovered orbiting the star using observations from the Spitzer Space Telescope.[4][5] Three of the seven (e, f, and g) are in the habitable zone.[6][7] TRAPPIST-1e is almost the same to Earth's mass, radius, density, gravity, temperature, and stellar flux.[1][2] It is also confirmed to not have a cloud-free hydrogen-dominated atmosphere, meaning it is more likely to have a compact atmosphere like the terrestrial planets in the Solar System.[8]
In November 2018, researchers decided that of the seven exoplanets in the multi-planetary system, TRAPPIST-1e has the best chance of being an Earth-like ocean planet, and the one most worthy of further study related to habitability.[9] What's more, according to the Habitable Exoplanets Catalog, TRAPPIST-1e is one of the most possible habitable exoplanets discovered.[10]