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 | |
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
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]
| 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
- 1 2 3 4 5 6 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
- 1 2 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
Coordinates: 
18h 02m 30.86s, +26° 18′ 46.81″
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