WR 156
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 23h 00m 10.13337s[1] |
| Declination | +60° 55′ 38.4168″[1] |
| Apparent magnitude (V) | 11.01[2] |
| Characteristics | |
| Spectral type | WN8h[3] |
| B−V color index | +1.17[2] |
| Astrometry | |
| Proper motion (μ) | RA: −4.71 ± 2.18[1] mas/yr Dec.: −0.92 ± 1.84[1] mas/yr |
| Parallax (π) | 0.07 ± 0.25[4] mas |
| Absolute magnitude (MV) | −7.22[5] |
| Details | |
| Mass | 38[5] M☉ |
| Radius | 22[3] R☉ |
| Luminosity | 650,000[3] L☉ |
| Temperature | 35,000[3] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
WR 156 is a Wolf–Rayet star in the constellation of Cepheus.
Distance
WR 156 has a Hipparcos parallax of 3.16" indicating a distance of about a thousand light years, although with a fairly large margin of error. Other studies indicate that it is much more distant based on a very high luminosity and faint apparent magnitude.[5] The Gaia DR1 parallax is 0.07". The margin of error is larger than the measured parallax, but still the indication is for a very large distance.[4]
Physical properties
WR 156 has a WR spectrum on the nitrogen sequence, indicating strong emission of helium and nitrogen, but it also shows features of hydrogen. Therefore it is given a spectral type of WN8h. Its outer layers are calculated to contain 30% hydrogen, one of the highest levels for any galactic Wolf Rayet star.[6]
WR 156 has a low temperature and slow stellar wind by Wolf Rayet standards, only 35,000 K and 550 km/s respectively. The wind is very dense, with total mass loss of more than 1/100,000 M☉/year.[3]
WR 156 is a member of the young hydrogen-rich stars which are still burning hydrogen in their cores, but are sufficiently luminous to have convected up nitrogen and helium fusion products to their surfaces. It is estimated to have had an initial mass of 50 M☉ several million years ago.[6]
References
- 1 2 3 4 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. Bibcode:2007A&A...474..653V. arXiv:0708.1752
. doi:10.1051/0004-6361:20078357. - 1 2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. ISBN 0333750888. doi:10.1888/0333750888/2862.
- 1 2 3 4 5 Maryeva, Olga (2016). "The study of massive stars with 50 Msun initial mass at different evolutionary stages". arXiv:1612.01191 [astro-ph.SR].
- 1 2 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.
- 1 2 3 Hamann, W.-R.; Gräfener, G.; Liermann, A. (2006). "The Galactic WN stars". Astronomy and Astrophysics. 457 (3): 1015. Bibcode:2006A&A...457.1015H. arXiv:astro-ph/0608078 . doi:10.1051/0004-6361:20065052.
- 1 2 Maryeva, O. V.; Afanasiev, V. L.; Panchuk, V. E. (2013). "Study of the late nitrogen-sequence Galactic Wolf-Rayet star WR156. Spectropolarimetry and modeling". New Astronomy. 25: 27. Bibcode:2013NewA...25...27M. doi:10.1016/j.newast.2013.03.015.