51 Pegasi b
The first exoplanet to be discovered around a main-sequence star / From Wikipedia, the free encyclopedia
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"Dimidium" redirects here. For the value, see half. For C. dimidium, see Caladenia dimidia.
51 Pegasi b, officially named Dimidium /dɪˈmɪdiəm/, is an extrasolar planet approximately 50 light-years (15 parsecs) away in the constellation of Pegasus. It was the first exoplanet to be discovered orbiting a main-sequence star,[2] the Sun-like 51 Pegasi, and marked a breakthrough in astronomical research. It is the prototype for a class of planets called hot Jupiters.[3]
Quick Facts Discovery, Discovered by ...
Discovery | |
---|---|
Discovered by | Michel Mayor and Didier Queloz |
Discovery site | OHP, France |
Discovery date | 6 October 1995; 28 years ago (6 October 1995) |
Radial velocity (ELODIE) | |
Designations | |
Dimidium | |
Orbital characteristics | |
Aphelion | 0.0534 AU (7,990,000 km) |
Perihelion | 0.0520 AU (7,780,000 km) |
0.0527 ± 0.0030 AU (7,880,000 ± 450,000 km) | |
Eccentricity | 0.013 ± 0.012 |
4.230785 ± 0.000036 d 101.5388 h | |
Average orbital speed | 136 km/s |
Star | 51 Pegasi |
Physical characteristics | |
Mean radius | 1.9±0.3 RJ[1] |
Mass | ≥0.472 ± 0.039 MJ |
Temperature | 1284 ± 19 K |
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In 2017, traces of water were discovered in the planet's atmosphere.[4] In 2019, the Nobel Prize in Physics was awarded in part for the discovery of 51 Pegasi b.[5]