HD 147506

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HD 147506
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Hercules[1]
Right ascension 16h 20m 36.36s[2]
Declination +41° 02′ 53.1″[2]
Apparent magnitude (V) +8.71[3]
Spectral type F8V[3]
U−B color index  ?
B−V color index  ?
Variable type planetary transit variable[4]
Radial velocity (Rv) ? km/s
Proper motion (μ) RA: –9.93 ± 0.84[2] mas/yr
Dec.: –28.26 ± 0.76[2] mas/yr
Parallax (π) 8.74 ± 0.73[2] mas
Distance 370 ± 30 ly
(114 ± 10 pc)
Absolute magnitude (MV) +3.31[5]
Mass 1.298 ± 0.1 M
Radius 1.412 ± 0.04 R
Luminosity 2.79 L
Surface gravity (log g) 4.14 ± 0.04[6] cgs
Temperature 6411 ± 64[6] K
Metallicity [Fe/H] 0.08 ± 0.07[6] dex
Rotational velocity (v sin i) 22.9 ± 1.5[6] km/s
Age 2.7 ± 1.4 Gyr
Other designations
HAT-P-2, HIP 80076, GSC 03065-01195, 2MASS J16203635+4102531[3]
Database references
Extrasolar Planets

HD 147506 is a magnitude 8.7 F8 dwarf star that is somewhat larger and hotter than our sun. The star is approximately 370 light years from Earth and is positioned near the keystone of Hercules.[3] It is estimated to be 2 to 3 billion years old.

Planetary system[edit]

Orbiting the star is HAT-P-2b, the most massive transiting extrasolar planet yet discovered.[4] 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 was speculated that another massive planet found outside the orbit of HAT-P-2b is in orbital resonance with HAT-P-2b.[7] Additional measurements taken over six years show a long-term linear trend in the radial velocity data consistent with a companion of 15 Jupiter masses or greater. Adaptive optics images were taken at the Keck telescope and when combined with the radial velocity data show the maximum mass of the companion is that of an M dwarf star.[8]

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.[9]

The HD 147506 planetary system[5][8]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
HAT-P-2b 8.00 ± 0.97 MJ 0.0663 ± 0.0039 5.6334729 ± 0.0000061 0.50910 ± 0.00048 85.97+0.28
1.106 ± 0.061 RJ

See also[edit]


  1. ^ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
  2. ^ a b c d e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  3. ^ a b c d "SIMBAD query result: NAME HAT-P-2 -- Star". Centre de Données astronomiques de Strasbourg. Retrieved 2009-04-24. 
  4. ^ a b Bakos, G. Á.; et al. (2007). "HD 147506b: A Supermassive Planet in an Eccentric Orbit Transiting a Bright Star". The Astrophysical Journal. 670 (1): 826–832. arXiv:0705.0126Freely accessible. Bibcode:2007ApJ...670..826B. doi:10.1086/521866. 
  5. ^ a b Pál, András; et al. (2010). "Refined stellar, orbital and planetary parameters of the eccentric HAT-P-2 planetary system". Monthly Notices of the Royal Astronomical Society. 401 (4): 2665–2674. arXiv:0908.1705Freely accessible. Bibcode:2010MNRAS.401.2665P. doi:10.1111/j.1365-2966.2009.15849.x. 
  6. ^ a b c d Torres, Guillermo; et al. (2012). "Improved Spectroscopic Parameters for Transiting Planet Hosts". The Astrophysical Journal. 757 (2). 161. arXiv:1208.1268Freely accessible. Bibcode:2012ApJ...757..161T. doi:10.1088/0004-637X/757/2/161. 
  7. ^ Alan MacRobert, “New Worlds roundup,” Sky and Telescope, August 2007, pg 15.
  8. ^ a b Lewis, Nikole K.; et al. (2013). "Orbital Phase Variations of the Eccentric Giant Planet HAT-P-2b". The Astrophysical Journal. 766 (2). 95. arXiv:1302.5084Freely accessible. Bibcode:2013ApJ...766...95L. doi:10.1088/0004-637X/766/2/95. 
  9. ^ Systemic Planetary Simulation

Coordinates: Sky map 16h 20m 36s, +41° 02′ 53″