HD 210702

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HD 210702
Observation data
Epoch J2000      Equinox J2000
Constellation Pegasus
Right ascension 22h 11m 51.33s[1]
Declination +16° 02′ 26.0″[1]
Apparent magnitude (V) 5.939
Characteristics
Spectral type K1IV
U−B color index 0.73
B−V color index 0.951[2]
R−I color index 0.49
Astrometry
Radial velocity (Rv) 10.9 ± 2 km/s
Proper motion (μ) RA: -3.15 ± 0.34[1] mas/yr
Dec.: -18.02 ± 0.33[1] mas/yr
Parallax (π) 18.20 ± 0.39[1] mas
Distance 179 ± 4 ly
(55 ± 1 pc)
Absolute magnitude (MV) 2.201
Details
Mass 1.68 (1.50–1.84)[2] M
Radius 5.1 (4.8–5.5)[2] R
Luminosity 14.1[2] L
Surface gravity (log g) 3.19 ± 0.08[2] cgs
Temperature 4967 ± 25[2] K
Metallicity 12 ± 4 %
Age 1.4 ± 1 G years
Other designations
BD+15º4592, HIP 109577, HR 8461, SAO 107729.
Database references
SIMBAD data
Extrasolar Planets
Encyclopaedia
data
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

HD 210702 is an orange subgiant star located approximately 179 light-years away in the constellation of Pegasus. With a mass of 1.8 times that of the Sun, the star spent its main-sequence life as an A-type star. The visual luminosity is 11.38 times that of the Sun and it is 182.4 light years away. The magnitude is near the naked-eye limit, but binoculars can easily see it.

The star shows variability in its radial velocity consistent with a planet-mass companion in a Keplerian orbit,[3] and one was duly discovered in April 2007, from observations at Lick and Keck Observatories in Mount Hamilton (California) and Mauna Kea (Hawai'i), USA.

The HD 210702 planetary system[2]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b >1.9 MJ 1.2 354.8 ± 1.1 0.094 ± 0.052

See also[edit]

References[edit]

  1. ^ a b c d e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c d e f g Bun'ei Sato et al. (2012). "Substellar Companions to Seven Evolved Intermediate-Mass Stars". PASJ. arXiv:1207.3141. Bibcode:2012PASJ...64..135S. doi:10.1093/pasj/64.6.135. 
  3. ^ Johnson, John Asher et al. (2007). "Retired A Stars and Their Companions: Exoplanets Orbiting Three Intermediate-Mass Subgiants". The Astrophysical Journal 665 (1): 785–793. arXiv:0704.2455. Bibcode:2007ApJ...665..785J. doi:10.1086/519677. 

Coordinates: Sky map 22h 11m 51.3311s, +16° 02′ 25.983″