12 Aurigae
12 Aurigae is a Be star in the northern constellation Auriga. It lies below the normal limit for visibility to the naked eye, having an apparent visual magnitude of 6.988.[2] It lacks a designation from the Hipparcos catalogue. It is located just under half a degree north of Capella.[8]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 16m 27.08298s[1] |
| Declination | +46° 24′ 57.8118″[1] |
| Apparent magnitude (V) | 6.988[2] |
| Characteristics | |
| Spectral type | B2 Ve[3] |
| Astrometry | |
| Proper motion (μ) | RA: −3.321[1] mas/yr Dec.: −1.2106[1] mas/yr |
| Parallax (π) | 1.5264 ± 0.0303 mas[1] |
| Distance | 2,140 ± 40 ly (660 ± 10 pc) |
| Details | |
| Mass | 3.0[4] M☉ |
| Radius | 18[5] R☉ |
| Luminosity | 635[5] L☉ |
| Surface gravity (log g) | 2.47[4] cgs |
| Temperature | 8,688[6] K |
| Metallicity | −0.94[4] |
| Rotational velocity (v sin i) | 100±41[7] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Assigned spectral classes for 12 Aurigae vary greatly from B2 to B5 and the luminosity class from V (main sequence) to Ia (luminous supergiant). Its spectrum shows prominent emission lines, but the spectrum is complicated by the appearance of sharp shell components to some of the spectral lines.[9] The colour of the star as shown by the B-V and U-B colour indices is not consistent with an early B spectral class,[10] leading to many estimates of its effective temperature that are much lower than expected for a B-class star.[6][4] The expected temperature for a B5 spectral type would be 15,400 K,[11] but most sources assign a temperature of around 8,000 K.[6][4] Other properties also vary between different sources, for example the bolometric luminosity derived from the distance and temperature is 25 L☉,[6] while it is 635 L☉ when derived by fitting the spectral energy distribution.[5] A calculation of the stellar properties assuming the maximum possible interstellar extinction in the direction of 12 Aurigae results in a temperature of 14,336 K and a luminosity of 8,092 L☉, although it is strongly noted that the likely extinction is much lower.[5]
References edit
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b Paunzen, E. (2015). "A new catalogue of Strömgren-Crawford uvbyβ photometry". Astronomy & Astrophysics. 580: A23. arXiv:1506.04568. Bibcode:2015A&A...580A..23P. doi:10.1051/0004-6361/201526413. S2CID 73623700.
- ^ Burbidge, G. R.; Burbidge, E. Margaret (September 1953). "The Balmer Decrement in Some Be Stars". Astrophysical Journal. 118: 252. Bibcode:1953ApJ...118..252B. doi:10.1086/145747.
- ^ a b c d e Anders, F.; Khalatyan, A.; Queiroz, A. B. A.; Chiappini, C.; Ardevol, J.; Casamiquela, L.; Figueras, F.; Jimenez-Arranz, O.; Jordi, C.; Monguio, M.; Romero-Gomez, M.; Altamirano, D.; Antoja, T.; Assaad, R.; Cantat-Gaudin, T.; Castro-Ginard, A.; Enke, H.; Girardi, L.; Guiglion, G.; Khan, S.; Luri, X.; Miglio, A.; Minchev, I.; Ramos, P.; Santiago, B. X.; Steinmetz, M. (2022). "VizieR Online Data Catalog: StarHorse2, Gaia EDR3 photo-astrometric distances (Anders+, 2022)". Vizier Online Data Catalog. Bibcode:2022yCat.1354....0A.
- ^ a b c d McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. eISSN 1365-2966. ISSN 0035-8711.
- ^ a b c d Stassun, Keivan G.; et al. (September 2018). "The TESS Input Catalog and Candidate Target List". The Astronomical Journal. 156 (3): 102. arXiv:1706.00495. Bibcode:2018AJ....156..102S. doi:10.3847/1538-3881/aad050. ISSN 0004-6256.
- ^ Halbedel, Elaine M. (September 1996). "Rotational Velocity Determinations for 164 Be and B Stars". Publications of the Astronomical Society of the Pacific. 108: 833. Bibcode:1996PASP..108..833H. doi:10.1086/133804.
- ^ a b "12 Aur". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-04.
- ^ Halbedel, Elaine M. (September 1996). "Rotational Velocity Determinations for 164 Be and B Stars". Publications of the Astronomical Society of the Pacific. 108: 833. Bibcode:1996PASP..108..833H. doi:10.1086/133804. S2CID 119944672.
- ^ Hamdy, M. A.; Elazm, M. S. A.; Saad, S. M. (1991). "Spectral reclassification of some be stars using ΔQ method". Astrophysics and Space Science. 186 (1): 161. Bibcode:1991Ap&SS.186..161H. doi:10.1007/BF00644632. S2CID 123509301.
- ^ Wright, Candace O.; et al. (2003). "The Tycho-2 Spectral Type Catalog". The Astronomical Journal. 125 (1): 359. Bibcode:2003AJ....125..359W. doi:10.1086/345511. S2CID 122781581.