| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
| Parent star | ||
| Star | GSC 02757-01152 | |
| Constellation | Pegasus | |
| Right ascension | (α) | 22h 52m 09.862s |
| Declination | (δ) | +35° 26′ 49.59″ |
| Apparent magnitude | (mV) | 10.17 |
| Distance | 750 ± 50 ly (230 ± 15 pc) |
|
| Orbital elements | ||
| Semimajor axis | (a) | 0.0487 ± 0.00026 AU |
| Eccentricity | (e) | ~0 |
| Orbital period | (P) | 3.07632 ± 0.000004 d |
| Orbital speed | (υ) | 173 km/s |
| Inclination | (i) | 87.5+1.9 −0.9° |
| Time of transit | (Tt) | 2,454,437.67582 ± 0.00034 JD |
| Physical characteristics | ||
| Mass | (m) | 1.52+0.18 −0.16 MJ |
| Radius | (r) | 1.5+0.08 −0.06 RJ |
| Discovery information | ||
| Discovery date | December 5, 2008 | |
| Discoverer(s) | HATNet Project | |
| Detection method | Transit | |
| Discovery status | Unpublished | |
| Database references | ||
| Extrasolar Planets Encyclopaedia |
data | |
| SIMBAD | data | |
HAT-P-8b is an extrasolar planet located approximately 750 light years away in the constellation of Pegasus, orbiting the 10th magnitude star GSC 02757-01152. This planet was discovered by transit on December 5, 2008. Despite the designation as HAT-P-8b, it is the 11th planet discovered by the HATNet Project. The mass of the planet is half more than Jupiter while the radius is also half more than Jupiter. The mass of this planet is exact since the inclination of the orbit is known, typical for transiting planets. This is a so-called “hot Jupiter” because this Jupiter-like gas giant planet orbits in a really close torch orbit around the star, making this planet extremely hot (in the order of a thousand kelvins). The distance from the star is roughly 20 times smaller that of Earth from the Sun, which places the planet roughly 8 times closer to its star than Mercury is from the Sun. The “year” on this planet lasts only 3 days, 1 hour, 49 minutes, and 54 seconds, compared with Earth's 365 days, 6 hours, 9 minutes, and 10 seconds in a sidereal year. [1]
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