WR 102
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 17h 45m 47.5s[1] |
| Declination | −26° 10′ 27″[1] |
| Apparent magnitude (V) | 14.10[2] |
| Characteristics | |
| Evolutionary stage | Wolf-Rayet star |
| Spectral type | WO2[3] |
| B−V color index | +0.77[4] |
| Astrometry | |
| Distance | 5,560[5] pc |
| Absolute magnitude (MV) | −1.71[2] |
| Details | |
| Mass | 19[2] M☉ |
| Radius | 0.39[3] R☉ |
| Luminosity | 282,000[3] L☉ |
| Temperature | 210,000[3] K |
| Metallicity [Fe/H] | 0.0[3] dex |
| Rotational velocity (v sin i) | 1,000[2] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
WR 102 is a Wolf-Rayet star in the constellation Cygnus, an extremely rare star on the WO oxygen sequence.
Features
WR 102, of spectral classification WO2, is one of the very few known oxygen-sequence Wolf-Rayet stars, just four in the Milky Way galaxy and five in external galaxies. It is also the hottest known with a surface temperature of 210,000 K. Modelling the atmosphere gives a luminosity around 282,000 L☉,[3] while calculations from brightness and distance gives luminosity of nearly 500,000 L☉ although the distance is not known with any certainty.[2] It is a very small dense star, with a radius less than 0.4 solar radii but with a mass nearly 20 solar masses. Very strong stellar winds, with a terminal velocity of 5,000 kilometers per second are causing WR 102 to lose 10−5 M☉/year.[2] For comparison, the Sun loses (2-3) x 10−14 solar masses per year due to its solar wind, several hundred million times less than WR 102.
Evolutionary status
WO Wolf-Rayet stars are the last evolutionary stage of the most massive stars before exploding as supernovae, possibly with a gamma-ray burst.[6] It is very likely that WR 102 is on its last stages of nuclear fusion, near or beyond the end of helium burning.[7] It will explode as a supernova very soon in astronomical terms, within a few thousand years. The mass and rapid rotation make a GRB likely.[3]
See also
References
- 1 2 Dufton, P. L.; Smartt, S. J.; Hambly, N. C. (2001). "A UKST survey of blue objects towards the Galactic centre - seven additional fields". Astronomy and Astrophysics 373 (2): 608–624. Bibcode:2001A&A...373..608D. doi:10.1051/0004-6361:20010613. ISSN 0004-6361.
- 1 2 3 4 5 6 Sander, A.; Hamann, W. -R.; Todt, H. (2012). "The Galactic WC stars". Astronomy & Astrophysics 540: A144. arXiv:1201.6354. Bibcode:2012A&A...540A.144S. doi:10.1051/0004-6361/201117830.
- 1 2 3 4 5 6 7 Tramper, F.; Straal, S. M.; Sanyal, D.; Sana, H.; de Koter, A.; Gräfener, G.; Langer, N.; Vink, J. S.; de Mink, S. E.; Kaper, L. (2015). "Massive stars on the verge of exploding: The properties of oxygen sequence Wolf-Rayet stars". Astronomy & Astrophysics 581 (110): A110. arXiv:1507.00839v1. Bibcode:2015A&A...581A.110T. doi:10.1051/0004-6361/201425390.
- ↑ Smith, Lindsey F.; Shara, Michael M.; Moffat, Anthony F. J. (1990). "Distances of Galactic WC stars from emission-line fluxes and a quantification of the WC classification". The Astrophysical Journal 358: 229. Bibcode:1990ApJ...358..229S. doi:10.1086/168978. ISSN 0004-637X.
- ↑ van der Hucht, Karel A. (2001). "The VIIth catalogue of galactic Wolf–Rayet stars". New Astronomy Reviews 45 (3): 135–232. Bibcode:2001NewAR..45..135V. doi:10.1016/S1387-6473(00)00112-3. ISSN 1387-6473.
- ↑ Groh, Jose H.; Meynet, Georges; Georgy, Cyril; Ekstrom, Sylvia (2013). "Fundamental properties of core-collapse Supernova and GRB progenitors: Predicting the look of massive stars before death". Astronomy & Astrophysics 558: A131. arXiv:1308.4681v1. Bibcode:2013A&A...558A.131G. doi:10.1051/0004-6361/201321906.
- ↑ Groh, Jose (2014). "The evolution of massive stars and their spectra I. A non-rotating 60 Msun star from the zero-age main sequence to the pre-supernova stage". Astronomy & Astrophysics 564: A30. arXiv:1401.7322. Bibcode:2014A&A...564A..30G. doi:10.1051/0004-6361/201322573.
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