30 Geminorum
30 Geminorum is a suspected astrometric binary[7] star system in the northern zodiac constellation of Gemini. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.49.[2] The distance to this star, as estimated through the use of parallax, is about 299 light years.[1] It is drifting further away from the Sun with a heliocentric radial velocity of +9.5 km/s.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Gemini |
| Right ascension | 06h 43m 59.28697s[1] |
| Declination | +13° 13′ 40.8188″[1] |
| Apparent magnitude (V) | 4.49[2] |
| Characteristics | |
| Spectral type | K0+ III Ca1[3] |
| B−V color index | 1.167±0.006[2] |
| Astrometry | |
| Radial velocity (Rv) | +9.50±0.25[4] km/s |
| Proper motion (μ) | RA: −0.269[1] mas/yr Dec.: −53.503[1] mas/yr |
| Parallax (π) | 10.9027 ± 0.2048[1] mas |
| Distance | 299 ± 6 ly (92 ± 2 pc) |
| Absolute magnitude (MV) | −0.25[2] |
| Details | |
| Mass | 2.29±0.62[5] M☉ |
| Radius | 22.4+0.5 −0.8[1] R☉ |
| Luminosity | 188.9±4.1[1] L☉ |
| Surface gravity (log g) | 2.18±0.11[5] cgs |
| Temperature | 4,518+82 −47[1] K |
| Metallicity [Fe/H] | −0.11±0.05[5] dex |
| Rotational velocity (v sin i) | 2.7[4] km/s |
| Age | 1.20+0.31 −0.25[5] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an aging giant star with a stellar classification of K0+ III Ca1,[3] having exhausted the supply of hydrogen at its core and expanded to 22[1] times the Sun's radius. The suffix notation indicates it displays an overabundance of calcium in its spectrum. It is a red clump giant,[8] which means it is on the horizontal branch and is generating energy through helium fusion at its core. The star is about 1.2[5] billion years old with 2.3[5] times the Sun's mass. It is radiating 189[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,518 K.[1]
There is a 13th magnitude visual companion located at an angular separation of 21.20″ along a position angle of 187° from the brighter star, as of 2011.[9]
References
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
- Keenan, P. C.; McNeil, R. C. (1989), "The Perkins catalog of revised MK types for the cooler stars", The Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
- Massarotti, Alessandro; et al. (2008), "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity", The Astronomical Journal, 135: 209, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
- Feuillet, Diane K.; et al. (2016), "Determining Ages of APOGEE Giants with Known Distances", The Astrophysical Journal, 817: 40, arXiv:1511.04088, Bibcode:2016ApJ...817...40F, doi:10.3847/0004-637X/817/1/40.
- "30 Gem". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-20.
- 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.
- Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278.
- Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
