Planetary System
On October 6, 1995, Swiss astronomers Michel Mayor and Didier Queloz announced the discovery of an exoplanet orbiting 51 Pegasi. The discovery was made with the radial velocity method on a telescope at Observatoire de Haute-Provence in France and using the ELODIE spectrograph. On October 12, 1995, confirmation came from Dr. Geoffrey Marcy from San Francisco State University and Dr. Paul Butler from the University of California, Berkeley using the Hamilton Spectrograph at the Lick Observatory near San Jose in California.
51 Pegasi b (51 Peg b) is the first discovered planetary-mass companion of its parent star. The planet has been informally named Bellerophon. After its discovery, many teams confirmed its existence and obtained more observations of its properties, including the fact that it orbits very close to the star, suffers estimated temperatures around 1200°C, and has a minimum mass about half that of Jupiter. At the time, this close distance was not compatible with theories of planet formation and resulted in discussions of planetary migration. It has been assumed that the planet shares the star's inclination of 79 degrees. But several "hot Jupiters" are known to be oblique relative to the stellar axis. As of 2012, no additional planets have been found orbiting this star.
| Companion |
Mass | Semimajor axis |
Orbital period |
Eccentricity | Radius |
|---|---|---|---|---|---|
| b | ≥ 0.472 ± 0.039 MJ | 0.0527 ± 0.0030 | 4.230785 ± 0.000036 | 0.013 ± 0.012 | — |
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