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 | |
| 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.
| 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
References
- 1 2 3 4 5 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 3 4 5 6 7 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.
- ↑ 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: 
22h 11m 51.3311s, +16° 02′ 25.983″
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