HD 17156

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HD 17156
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia
Right ascension 02h 49m 44.49s[1]
Declination +71° 45′ 11.6″[1]
Apparent magnitude (V) 8.17[2]
Spectral type G0IV[3]
Apparent magnitude (B) 8.76[2]
Apparent magnitude (V) 8.17[2]
Radial velocity (Rv) −3.15 ± 0.20[4] km/s
Proper motion (μ) RA: 91.14 ± 0.49[1] mas/yr
Dec.: -33.14 ± 0.56[1] mas/yr
Parallax (π) 13.33 ± 0.72[1] mas
Distance 240 ± 10 ly
(75 ± 4 pc)
Absolute magnitude (MV) 3.70
Mass 1.275 ± 0.018[5] M
Radius 1.5007 ± 0.0076[5] R
Temperature 6079 ± 80[6] K
Metallicity [Fe/H] 0.24 ± 0.05[6] dex
Age 3.37 +0.20
[5] Gyr
Other designations
BD+71°171, HIP 13192, SAO 4737, GSC 04321-01320, PPM 5099, TYC 4321-1320-1, AG+71 95 [2]
Database references
Extrasolar Planets

HD 17156 is a yellow subgiant star approximately 240 light-years away[1] in the constellation of Cassiopeia. The apparent magnitude is 8.17, which means it is not visible to the naked eye but can be seen with good binoculars.[2] A search for a binary companion star using adaptive optics at the MMT Observatory was negative.[7]

The star is more massive and larger than our Sun while Its absolute magnitude of 3.70 and spectral type of G0, show that it is both hotter and more luminous. Based on asteroseismic density constraints and stellar isochrones, it was found that the age is 3.37 +0.20
billion years making it about two thirds as old as the sun. Spectral observations show that the star is metal-rich.[3][5]

An extrasolar planet was discovered with the radial velocity method in 2007, it was subsequently discovered to transit the star. At the time it was the transiting planet with the longest period.[3][8]

Planetary system[edit]

It is the first star in Cassiopeia around which an orbiting planet was discovered (in 2007) using the radial velocity method. Later observations showed that this planet also transited the star.[8] In February 2008, a second planet, HD 17156 c, was proposed, with a 5:1 mean motion resonance to the inner planet HD 17156 b.[9]

The HD 17156 planetary system[5][9]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b 3.191 ± 0.033 MJ 0.16243 21.2163979 ± 0.0000159 0.6768 ± 0.0034
c (unconfirmed) 0.063 MJ 0.481 111.314 0.136

See also[edit]


  1. ^ a b c d e f van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752free to read. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c d e "SIMBAD query result: HIP 13192 -- Star". Centre de Données astronomiques de Strasbourg. Retrieved 2009-05-20. 
  3. ^ a b c Fischer, Debra A.; et al. (2007). "Five Intermediate-Period Planets from the N2K Sample". The Astrophysical Journal. 669 (2): 1336–1344. arXiv:0704.1191free to read. Bibcode:2007ApJ...669.1336F. doi:10.1086/521869. 
  4. ^ Barbieri, M.; et al. (2009). "Characterization of the HD 17156 planetary system". Astronomy and Astrophysics. 503 (2): 601–612. arXiv:0812.0785free to read. Bibcode:2009A&A...503..601B. doi:10.1051/0004-6361/200811466. 
  5. ^ a b c d e Nutzman, Philip; et al. (2011). "Precise Estimates of the Physical Parameters for the Exoplanet System HD 17156 Enabled by Hubble Space Telescope Fine Guidance Sensor Transit and Asteroseismic Observations". The Astrophysical Journal. 726 (1). article number 3. arXiv:1011.0440free to read. Bibcode:2011ApJ...726....3N. doi:10.1088/0004-637X/726/1/3. 
  6. ^ a b Winn, Joshua N.; et al. (2009). "The Transit Light Curve Project. X. A Christmas Transit of HD 17156b". The Astrophysical Journal. 693 (1): 794–803. arXiv:0810.4725free to read. Bibcode:2009ApJ...693..794W. doi:10.1088/0004-637X/693/1/794. 
  7. ^ Adams, E. R.; et al. (2013). "Adaptive Optics Images. II. 12 Kepler Objects of Interest and 15 Confirmed Transiting Planets". The Astronomical Journal. 146 (1). 9. arXiv:1305.6548free to read. Bibcode:2013AJ....146....9A. doi:10.1088/0004-6256/146/1/9. 
  8. ^ a b Barbieri, M.; et al. (2007). "HD 17156b: A Transiting Planet with a 21.2 Day Period and an Eccentric Orbit". Astronomy and Astrophysics Letters. 476 (2): L13–L16. arXiv:0710.0898free to read. Bibcode:2007A&A...476L..13B. doi:10.1051/0004-6361:20078787. 
  9. ^ a b Short, Donald; et al. (2008). "Orbital Dynamics Of A Possible Second Planet In HD 17156". arXiv:0803.2935free to read. Bibcode:2008arXiv0803.2935S. 

External links[edit]

Coordinates: Sky map 02h 49m 44.49s, +71° 45′ 11.64″