| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Hercules |
| Right ascension | 16h 20m 36.36s[1] |
| Declination | +41° 02′ 53.1″[1] |
| Apparent magnitude (V) | +8.71[1] |
| Characteristics | |
| Spectral type | F8V[1] |
| U−B color index | ? |
| B−V color index | ? |
| Variable type | none |
| Astrometry | |
| Radial velocity (Rv) | ? km/s |
| Proper motion (μ) | RA: −10.64 mas/yr Dec.: −29.70 mas/yr |
| Parallax (π) | 7.39 ± 0.88 mas |
| Distance | 440 ly (135 pc) |
| Absolute magnitude (MV) | +3.04 |
| Details | |
| Mass | 1.298 ± 0.1 M☉ |
| Radius | 1.412 ± 0.04 R☉ |
| Surface gravity (log g) | 4.33 |
| Luminosity | 2.79 L☉ |
| Temperature | 6290 ± 110 K |
| Metallicity | +0.12 ± 0.08 |
| Rotation | ? |
| Age | 2.7 ± 1.4 × 109 years |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Extrasolar Planets Encyclopaedia |
data |
HD 147506 is a magnitude 8.7 F8 dwarf star that is somewhat larger and hotter than our sun. The star is 440 light years from Earth and is positioned near the keystone of Hercules.[1] It is estimated to be 2 to 3 billion years old.
Orbiting the star is HAT-P-2b, the most massive transiting extrasolar planet yet discovered.[2] At 9.04 MJ and an estimated surface temperature of ~900 kelvins, on a 5.6 day orbit, this planet is unlike any previously discovered transiting planet. The planet has a large mass (nine times the mass of Jupiter), and a surface gravity 25 times that exerted by the Earth. Its orbital eccentricity is very large (e = 0.5). Since tidal forces should have reduced the orbital eccentricity of this planet it is speculated that another massive planet found outside the orbit of HAT-P-2b is in orbital resonance with HAT-P-2b.[3]
The planet was discovered by the HATNet Project and the researchers there believed the planet to be 10-20% larger than Jupiter. This discovery is important as it provides further support for the existing theory of planetary structure.[4]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| HAT-P-2b | 9.04 (± 0.50) MJ | 0.520 ±0.010 | 5.63341 ±0.00013 | 0.520 ±0.010) |