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Discovery[1] | |
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Discovered by | David Charbonneau, et al. |
Discovery site | Fred Lawrence Whipple Observatory |
Discovery date | December 16, 2009 |
Transit (MEarth Project) | |
Designations | |
Enaiposha,[2] Gliese 1214 b | |
Orbital characteristics[3] | |
0.01490±0.00026 AU | |
Eccentricity | < 0.063 |
1.580404571(42) d[4] | |
Inclination | 88.7°±0.1° |
Semi-amplitude | 14.36±0.53 m/s |
Star | Orkaria/GJ 1214 |
Physical characteristics | |
2.742+0.050 −0.053 R🜨[3] | |
Mass | 8.17±0.43 M🜨[3] |
Mean density | 2.20+0.17 −0.16 g/cm3[3] |
10.65+0.71 −0.67 m/s2[3] (1.09 g) | |
19.31+0.53 −0.54 km/s[3] | |
Albedo | 0.51±0.06 (Bond)[5] |
Temperature | 553±9 K (280 °C; 536 °F, dayside)[5] 437±19 K (164 °C; 327 °F, nightside)[5] |
GJ 1214 b (sometimes Gliese 1214 b,[6] also named Enaiposha since 2023[2]) is an exoplanet that orbits the star GJ 1214, discovered in December 2009. Its parent star is 48 light-years (15 pc) from the Sun, in the constellation Ophiuchus. At the time of its discovery, GJ 1214 b was the most likely known candidate for being an ocean planet.[1][7] For that reason, scientists at that time often called the planet a "waterworld".[8] However, a recent study of the planet's internal structure informed by observations taken with the James Webb Space Telescope suggests that a "waterworld" composition is implausible and the planet is more likely to host a thick gaseous envelope consisting of hydrogen, helium, water and other volatile chemicals such as methane or carbon dioxide.[9]
It is a mini-Neptune, meaning it is larger than Earth but is significantly smaller (in mass and radius) than the gas giants of the Solar System. After CoRoT-7b, it was the second planet between Earth and Neptune in mass to have both its mass and radius measured[1] and is the first of a new class of planets with small size and relatively low density.[10] GJ 1214 b is also significant because its parent star is relatively near the Sun and because it transits that parent star, which allows the planet's atmosphere to be studied using spectroscopic methods.[1]
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