WR 1
| Observation data Epoch 2000 Equinox 2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 00h 43m 28.39827s[1] |
| Declination | +64° 45′ 35.4011″[1] |
| Apparent magnitude (V) | 10.54[2] |
| Characteristics | |
| Evolutionary stage | Wolf-Rayet |
| Spectral type | WN4-s[3] |
| U−B color index | −0.24[4] |
| B−V color index | +0.37[4] |
| Variable type | WR[2] |
| Astrometry | |
| Proper motion (μ) | RA: −1.32[1] mas/yr Dec.: −1.19[1] mas/yr |
| Parallax (π) | 0.15 ± 0.23 mas[5] |
| Distance | 1,820[6] pc |
| Absolute magnitude (MV) | −3.54[3] |
| Details | |
| Mass | 15[3] M☉ |
| Radius | 1.33[3] R☉ |
| Luminosity | 250,000[3] L☉ |
| Temperature | 112,200[3] K |
| Rotational velocity (v sin i) | 6.5[7] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
WR 1 is a Wolf-Rayet star located around 6,000 light years away from Earth in the constellation of Cassiopeia. It is only a third larger than the sun, but due to a temperature over 100,000 K it is 250,000 times as luminous as the sun.
Although WR 1 has been recognised as a Wolf-Rayet star since the 19th century,[8] the WR 1 designation does not indicate that it was the first to be discovered. Ordered by right ascension, WR 1 was the first star in the The Sixth Catalogue of galactic Wolf-Rayet stars.[9]
WR 1 is a member of the nitrogen sequence of WR stars and has a spectrum with HeII lines much stronger than HeI lines. NIII and NIV emission more than twice the strength of NIII, leading to the assignment of a WN4 spectral type. The spectrum has particularly wide HeII, leading to the equivalent classifications of WN4-b (for broad) or WN4-s (for strong). The spectrum also includes CIV and NV, but no hydrogen lines at all.[10][11]
WR 1 is slightly variable and given the designation V863 Cassiopeiae. The total amplitude of the variations is only 0.09 magnitudes at visual wavelengths. The variations are well-defined with a period of 16.9 days, but the light curve is not sinusoidal and its shape may vary.[12] The variations have been ascribed to a dense asymmetric stellar wind and co-rotating interacting regions in ejected material.[7]
It has been suggested that the variability and an infrared excess could be due to a cool companion, but WR 1 is now considered to be a single star.[11] The WN-b subclass of Wolf-Rayet star are generally thought to be all single, in contrast with the WN-A subclass which have narrow emission on a stronger continuum and are thought to be binary systems with a more conventional hot luminous star.[10]
References
- ^ a b c d Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- ^ 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 e f Hamann, W. -R.; Gräfener, G.; Liermann, A. (2006). "The Galactic WN stars". Astronomy and Astrophysics. 457 (3): 1015. arXiv:astro-ph/0608078. Bibcode:2006A&A...457.1015H. doi:10.1051/0004-6361:20065052.
- ^ a b Pyper, Diane M. (1966). "The Effective Temperatures of Wolf-Rayet Stars as Derived from Their U BV Color Indices Corrected for Emission". Astrophysical Journal. 144: 13. Bibcode:1966ApJ...144...13P. doi:10.1086/148587.
- ^ Gaia Collaboration (2016). "VizieR Online Data Catalog: Gaia DR1 (Gaia Collaboration, 2016)". VizieR On-line Data Catalog: I/337. Originally published in: Astron. Astrophys. 1337. Bibcode:2016yCat.1337....0G.
- ^ Van Der Hucht, K. A. (2001). "The VIIth catalogue of galactic Wolf–Rayet stars". New Astronomy Reviews. 45 (3): 135. Bibcode:2001NewAR..45..135V. doi:10.1016/S1387-6473(00)00112-3.
- ^ a b St-Louis, N. (2013). "Revealing the Asymmetry of the Wind of the Variable Wolf-Rayet Star WR1 (HD 4004) through Spectropolarization". The Astrophysical Journal. 777: 9. arXiv:1308.5914. Bibcode:2013ApJ...777....9S. doi:10.1088/0004-637X/777/1/9.
- ^ Campbell, W. W. (1894). "The Wolf-Rayet stars". Astronomy and Astro-Physics (formerly the Sidereal Messenger). 13. Bibcode:1894AstAp..13..448C.
- ^ Van Der Hucht, Karel A.; Conti, Peter S.; Lundström, Ingemar; Stenholm, Björn (1981). "The Sixth Catalogue of galactic Wolf-Rayet stars, their past and present". Space Science Reviews. 28 (3): 227–306. Bibcode:1981SSRv...28..227V. doi:10.1007/BF00173260.
- ^ a b 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: 163. Bibcode:1996MNRAS.281..163S. doi:10.1093/mnras/281.1.163.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b Niedzielski, Andrzej (1998). "The Optical Spectrum of HD 4004 (WN4b). Evidence of Variability". Acta Astronomica. 48: 729. Bibcode:1998AcA....48..729N.
- ^ Chené, A.-N.; St-Louis, N. (2010). "Large-scale Periodic Variability of the Wind of the Wolf-Rayet Star WR 1 (HD 4004)". The Astrophysical Journal. 716 (2): 929. arXiv:1004.4893. Bibcode:2010ApJ...716..929C. doi:10.1088/0004-637X/716/2/929.
