HAT-P-2 b
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| Extrasolar planet | List of extrasolar planets | ||
|---|---|---|---|
| Parent star | |||
| Star | HD 147506 | ||
| Constellation | Hercules | ||
| Right ascension | (α) | 16h 20m 36s | |
| Declination | (δ) | +41° 02′ 53″ | |
| Distance | 440 ± 52 ly (135 ± 16 pc) | ||
| Spectral type | F8V | ||
| Orbital elements | |||
| Semimajor axis | (a) | 0.0677+0.0011-0.0017[1] AU | |
| Eccentricity | (e) | 0.5163+0.0025-0.0023[1] | |
| Orbital period | (P) | 5.63341±0.00013 days[1] d | |
| Inclination | (i) | 90+0.85-0.93[1]° | |
| Angular distance | (θ) | 0.501 mas | |
| Longitude of periastron |
(ω) | 189.921.06-1.2[1]° | |
| Time of periastron | (T0) | 2,454,213.4794+0.0053-0.003[1] JD | |
| Semi-amplitude | (K) | 885±37 m/s | |
| Physical characteristics | |||
| Mass | (m) | 8.65+0.39-0.55[1] MJ | |
| Radius | (r) | 0.951+0.009-0.053[1] RJ | |
| Density | (ρ) | 12500+2.6-3.6[1] kg/m3 | |
| Surface gravity | (g) | 235.5 m/s² (24.01 g) | |
| Temperature | (T) | 1187[2] K | |
| Discovery information | |||
| Discovery date | 2007-05-02 | ||
| Discoverer(s) | HATNet Project | ||
| Detection method | Transit | ||
| Discovery status | Published | ||
HAT-P-2 b is an extrasolar planet detected by the HATNet Project in May 2007. It orbits a class F star, (bigger and hotter than the Sun), located about 440 light-years away in the constellation Hercules. Every 5 days 15 hours, it crosses directly in front of the star as viewed from Earth.[3]
| HAT-P-2 b | Jupiter |
|---|---|
 |
 |
The planet's mass has been estimated to be 8.65 times that of Jupiter, while its radius is 0.951 times that of Jupiter. Its small size despite the bloating of planet's atmosphere is caused by the strong gravitational pull of the massive planet pulling towards the center. This indicates that the planet's mean density is two times that of Earth and its surface gravity is approximately 24 times that on Earth. The orbit is very eccentric, ranging from 4.90 million miles to 15.36 million miles from the star; if Earth's orbit were as eccentric its distance from the sun would vary from a distance of 0.4837 AU to a distance equivalent to Mars (1.5163 AU).[3]
It has been suggested that there is a second outer planet perturbing HAT-P-2 b. This has not so far been proved or disproved.[3]
In addition to heat from its primary star, tidal heating is thought to have played a significant role in this planet's evolution.[4]
[edit] References
- ^ a b c d e f g h i "journal=Astronomy & Astrophysics Refined parameters and spectroscopic transit of the super-massive planet HD 147506b" (2008) 481: 529-533.
- ^ Ravilious, Kate. ""Weird" New Planet Weighs as Much as 2,500 Earths", National Geographic News, May 3, 2007. Retrieved on 2007-05-04.
- ^ a b c Harvard-Smithsonian Center for Astrophysics (May 2, 2007). "Astronomers find super-massive planet". Press release.
- ^ Jackson, Brian; Richard Greenberg, Rory Barnes (2008). "Tidal Heating of Extra-Solar Planets". ApJ. arXiv:0803.0026.
