HD 147506

HD 147506 is a magnitude 8.7 F8 dwarf star that is somewhat larger and hotter than our sun. The star is approximately 418 light years from Earth and is positioned near the keystone of Hercules.[3] It is estimated to be 2 to 3 billion years old. There is one known transiting extrasolar planet.

HD 147506
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Hercules[1]
Right ascension  16h 20m 36.3579s[2]
Declination +41° 02′ 53.1090″[2]
Apparent magnitude (V) +8.71[3]
Characteristics
Spectral type F8V[3]
Variable type planetary transit variable[4]
Astrometry
Proper motion (μ) RA: −10.312±0.041[2] mas/yr
Dec.: −29.198±0.052[2] mas/yr
Parallax (π)7.7975 ± 0.0258[2] mas
Distance418 ± 1 ly
(128.2 ± 0.4 pc)
Absolute magnitude (MV)+3.31[5]
Details
Mass1.298 ± 0.1 M☉
Radius1.412 ± 0.04 R☉
Luminosity2.79 L☉
Surface gravity (log g)4.14 ± 0.04[6] cgs
Temperature6411 ± 64[6] K
Metallicity [Fe/H]0.08 ± 0.07[6] dex
Rotational velocity (v sin i)22.9 ± 1.5[6] km/s
Age2.7 ± 1.4 Gyr
Other designations
HAT-P-2, BD+41°2693, HIP 80076, SAO 46035[3]
Database references
SIMBADdata
Extrasolar Planets
Encyclopaedia		data

The star HD 147506 is named Hunor. The name was selected in the NameExoWorlds campaign by Hungary, during the 100th anniversary of the IAU. Hunor was a legendary ancestor of the Huns and the Hungarian nation, and brother of Magor (name of the planet HD 147506 b).[7][8]

Variability

In addition to being a planetary transit variable there is also stellar pulsations induced by the planet. This is the first known instance of a planet inducing pulsations in its host star. The amplitude is very small at approximately 40 parts per million. These pulsations correspond to exact harmonics of the planet's orbital frequency, indicating they are of a tidal origin.[9]

Planetary system

Orbiting the star is HAT-P-2b, which was at the time of its discovery the most massive transiting extrasolar planet.[4] At almost 9 times the mass of Jupiter 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.[10] 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.[11]

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.[12]

The HD 147506 planetary system[5][11][13]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 8.70+0.19
−0.20 MJ		 0.06880+0.00065
−0.00070		 5.6334729±0.0000061 0.50833+0.00082
−0.00075		 85.97+0.28
−0.25°		 1.106 ± 0.061 RJ

See also
  • List of transiting extrasolar planets

References
  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. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  3. "HD 147506". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2009-04-24.
  4. 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:0705.0126. Bibcode:2007ApJ...670..826B. doi:10.1086/521866.
  5. 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:0908.1705. Bibcode:2010MNRAS.401.2665P. doi:10.1111/j.1365-2966.2009.15849.x.
  6. Torres, Guillermo; et al. (2012). "Improved Spectroscopic Parameters for Transiting Planet Hosts". The Astrophysical Journal. 757 (2). 161. arXiv:1208.1268. Bibcode:2012ApJ...757..161T. doi:10.1088/0004-637X/757/2/161.
  7. "Approved names". NameExoworlds. Retrieved 2020-01-02.
  8. "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
  9. Wit, Julien de; et al. (2017). "Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System". The Astrophysical Journal Letters. 836 (2). L17. arXiv:1702.03797. Bibcode:2017ApJ...836L..17D. doi:10.3847/2041-8213/836/2/L17.
  10. Alan MacRobert, “New Worlds roundup,” Sky and Telescope, August 2007, pg 15.
  11. Lewis, Nikole K.; et al. (2013). "Orbital Phase Variations of the Eccentric Giant Planet HAT-P-2b". The Astrophysical Journal. 766 (2). 95. arXiv:1302.5084. Bibcode:2013ApJ...766...95L. doi:10.1088/0004-637X/766/2/95.
  12. Systemic Planetary Simulation
  13. Bonomo, A. S.; et al. (2017). "The GAPS Programme with HARPS-N at TNG . XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy and Astrophysics. 602. A107. arXiv:1704.00373. Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882.

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