WR 12 (V378 Velorum) is a spectroscopic binary in the constellation Vela. It is an eclipsing binary consisting of a Wolf-Rayet star and a luminous companion of unknown spectral type. The primary is one of the most luminous stars known.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Vela |
| Right ascension | 08h 44m 47.290s[2] |
| Declination | −45° 58′ 55.42″[2] |
| Apparent magnitude (V) | 10.78[3] |
| Characteristics | |
| Spectral type | WN8h[4] |
| U−B color index | –0.39[3] |
| B−V color index | +0.56[3] |
| Variable type | Algol + WR[5] |
| Astrometry | |
| Proper motion (μ) | RA: −2.979[2] mas/yr Dec.: +3.777[2] mas/yr |
| Parallax (π) | 0.1756 ± 0.0129 mas[2] |
| Distance | 19,000 ± 1,000 ly (5,700 ± 400 pc) |
| Absolute magnitude (MV) | −6.68[4] (−6.5 + −5.5[6]) |
| Orbit[7] | |
| Period (P) | 23.92336±0.00001 d |
| Eccentricity (e) | 0 |
| Inclination (i) | 78.8[6]° |
| Periastron epoch (T) | 2,449,811.188±0.065 |
| Semi-amplitude (K1) (primary) | 141.9±2.2 km/s |
| Details[4] | |
| WR | |
| Mass | 30 M☉ |
| Radius | 16.38 R☉ |
| Luminosity (bolometric) | 851,000[8] L☉ |
| Temperature | 44,700 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectrum of WR 12 is dominated by the broad emission lines of the primary Wolf-Rayet star. The lowest ionisation nitrogen emission lines are strongest, with NV lines being very weak. The HeI lines are stronger than the HeII lines. Unusually the hydrogen emission is stronger still, leading to a WN8h spectral class. CIV emission is almost undetectable.[9] It has been suggested that the companion is a class O star, but its lines cannot be seen in the spectrum.[6]
The system produces eclipses which dim the brightness of the star by 0.12 magnitudes every 24 days. The stars are detached and so it is classified as an Algol-type eclipsing binary. The inclination of the orbit has been estimated at 78.8° but a full orbital solution is not available because the secondary cannot be directly detected.[5][6]
References
edit- ^ "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 6 January 2022.
- ^ 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 c Moffat, A. F. J.; Vogt, N. (1975). "Southern open star clusters IV. UBV-Hbeta photometry of 26 clusters from Monoceros to Vela". Astronomy and Astrophysics. 20: 85. Bibcode:1975A&AS...20...85M.
- ^ a b c Sota, A.; Maíz Apellániz, J.; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J.; Oskinova, L. M. (2019). "The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters". Astronomy & Astrophysics. A57: 625. arXiv:1904.04687. Bibcode:2019A&A...625A..57H. doi:10.1051/0004-6361/201834850. S2CID 104292503.
- ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
- ^ a b c d Lamontagne, Robert; Moffat, Anthony F. J.; Drissen, Laurent; Robert, Carmelle; Matthews, Jaymie M. (1996). "Photometric Determination of Orbital Inclinations and Mass Loss Rates for Wolf-Rayet Stars in WR+O Binaries". Astronomical Journal. 112: 2227. Bibcode:1996AJ....112.2227L. doi:10.1086/118175.
- ^ Fahed, R.; Moffat, A. F. J. (2012). "Colliding winds in five WR+O systems of the Southern hemisphere". Monthly Notices of the Royal Astronomical Society. 424 (3): 1601. Bibcode:2012MNRAS.424.1601F. doi:10.1111/j.1365-2966.2012.20494.x.
- ^ Crowther, Paul A.; Rate, Gemma (2020). "Unlocking Galactic Wolf–Rayet stars with Gaia DR2 – I. Distances and absolute magnitudes". Monthly Notices of the Royal Astronomical Society. 493 (1): 1512–1529. arXiv:1912.10125. Bibcode:2020MNRAS.493.1512R. doi:10.1093/mnras/stz3614. S2CID 209444955.
- ^ Smith, Lindsey F.; Shara, Michael M.; Moffat, Anthony F. J. (1996). "A three-dimensional classification for WN stars". Monthly Notices of the Royal Astronomical Society. 281 (1): 163–191. Bibcode:1996MNRAS.281..163S. doi:10.1093/mnras/281.1.163.