Omega1 Tauri
Omega1 Tauri is a solitary,[7] orange hued star in the zodiac constellation of Taurus. It is faintly visible to the naked eye with an apparent visual magnitude of +5.51.[2] Based upon an annual parallax shift of 11.22 mas as seen from Earth,[1] it is located about 290 light years from the Sun.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Taurus | 
| Right ascension | 02h 12m 22.28003s[1] | 
| Declination | +30° 18′ 11.0430″[1] | 
| Apparent magnitude (V) | +5.51[2] | 
| Characteristics | |
| Spectral type | K2 III[2] | 
| B−V color index | 1.077[2] | 
| Astrometry | |
| Radial velocity (Rv) | +24.75±0.02[2] km/s | 
| Proper motion (μ) | RA: −65.05[1] mas/yr Dec.: −60.50[1] mas/yr | 
| Parallax (π) | 11.22 ± 0.70 mas[1] | 
| Distance | 290 ± 20 ly (89 ± 6 pc) | 
| Absolute magnitude (MV) | +0.76[2] | 
| Details | |
| Mass | 1.53[3] M☉ | 
| Radius | 12[4] R☉ | 
| Luminosity | 57.5[3] L☉ | 
| Surface gravity (log g) | 2.5[5] cgs | 
| Temperature | 4,737±77[3] K | 
| Metallicity [Fe/H] | 0.12[5] dex | 
| Rotational velocity (v sin i) | 4.6[4] km/s | 
| Age | 4.21[3] Gyr | 
| Other designations | |
| Database references | |
| SIMBAD | data | 
This is an evolved K-type giant star with a stellar classification of K2 III.[2] At the estimated age of 4.2 billion years,[3] it is a red clump star that is generating energy by helium fusion at its core.[5] Omega1 Tauri has about 1.5[3] times the mass of the Sun and has expanded to around 12[4] times the Sun's radius. It is radiating 57.5 times the Sun's luminosity from its photosphere at an effective temperature of 4,737 K.[3] The radial velocity of this star shows no appreciable variation, and for this reason it is used as a radial velocity standard.[2]
References
    
- 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, S2CID 18759600.
- Hekker, S.; et al. (August 2006), "Precise radial velocities of giant stars. I. Stable stars", Astronomy and Astrophysics, 454 (3): 943–949, arXiv:astro-ph/0604502, Bibcode:2006A&A...454..943H, doi:10.1051/0004-6361:20064946, S2CID 119529768.
- Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
- Massarotti, Alessandro; et al. (January 2008), "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
- Tautvaišienė, G.; et al. (March 2013), "Red clump stars of the Milky Way - laboratories of extra-mixing", Monthly Notices of the Royal Astronomical Society, 430 (1): 621−627, arXiv:1304.4393, Bibcode:2013MNRAS.430..621T, doi:10.1093/mnras/sts663, S2CID 119211439.
- "ome01 Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-30.
- Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.