HD 164922

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HD 164922
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Hercules
Right ascension 18h 02m 30.86s[1]
Declination +26° 18′ 46.81″[1]
Apparent magnitude (V) +7.01
Characteristics
Spectral type K0V
U−B color index 0.47
B−V color index 0.80
V−R color index 0.42
R−I color index 0.36
Variable type suspected
Astrometry
Radial velocity (Rv) +22.8 km/s
Proper motion (μ) RA: 389.41 ± 0.36[1] mas/yr
Dec.: –602.03 ± 0.52[1] mas/yr
Parallax (π) 45.21 ± 0.54[1] mas
Distance 72.1 ± 0.9 ly
(22.1 ± 0.3 pc)
Absolute magnitude (MV) 5.31
Details
Mass 0.94 M
Radius 0.9 R
Luminosity 0.608 L
Surface gravity (log g) 4.53 cgs
Temperature 5385 K
Metallicity [Fe/H] 0.17 dex
Rotation ~58.7
Age 13.4 Gyr
Other designations
BD +26°3151, GJ 700.2, LFT 1388, SAO 85678, HIP 88348

HD 164922 is a seventh magnitude star in the constellation of Hercules. It is an orange dwarf with a spectral type K0V. To view it, binoculars or a telescope are necessary, as it is too faint to be visible to the naked eye. It is 72 light years distant from the Earth.[1] At an age of 13.4 Gyr, it will soon evolve away from the main-sequence and expand to become a red giant. Its metallicity is nearly 50% more than the Sun. It is one of the oldest known stars in the Universe and one of the most ancient objects known in the Milky Way.

Planetary system[edit]

On 15 July 2006, a long period Saturn-mass exoplanet was announced orbiting around HD 164922. This planet orbits at 2.11 AU from the star with a low eccentricity value of 0.05.[2]

The HD 164922 planetary system[2]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b ≥0.360 ± 0.046 MJ 2.11 ± 0.13 1155 ± 23 0.05 ± 0.14


References[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:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  2. ^ a b Butler, R. P. et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. 

External links[edit]

Coordinates: Sky map 18h 02m 30.86s, +26° 18′ 46.81″