Astronomy:WR 156
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cepheus[1] |
| Right ascension | 23h 00m 10.12539s[2] |
| Declination | +60° 55′ 38.4109″[2] |
| Apparent magnitude (V) | 11.01[3] |
| Characteristics | |
| Evolutionary stage | Wolf-Rayet[4] |
| Spectral type | WN8h[5] |
| B−V color index | +1.17[3] |
| Astrometry | |
| Proper motion (μ) | RA: −2.596[2] mas/yr Dec.: −1.768[2] mas/yr |
| Parallax (π) | 0.2749 ± 0.0125[2] mas |
| Distance | 11,900 ± 500 ly (3,600 ± 200 pc) |
| Absolute magnitude (MV) | −7.00[6] |
| Details | |
| Mass | 32[6] M☉ |
| Radius | 20.81[6] R☉ |
| Luminosity | 1,023,000[6] L☉ |
| Temperature | 39,800[6] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
WR 156 is a young massive and luminous Wolf–Rayet star in the constellation of Cepheus. Although it shows a WR spectrum, it is thought to be a young star still fusing hydrogen in its core.
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.[6] 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.[7] In Gaia Data Release 2, the parallax is given as 0.2090±0.0251 mas but with a marker that the result may be unreliable.[8] In Gaia Data Release 3, the solution was adjusted to 0.2749±0.0125 mas, still with significant astrometric noise excess.[2]
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.[4]
WR 156 has a low temperature and slow stellar wind by Wolf Rayet standards, only 39,800 K and 660 km/s respectively. The wind is very dense, with total mass loss of more than 1/100,000 M☉/year.[6]
WR 156 is a young hydrogen-rich star, still burning hydrogen in its core but sufficiently luminous to have convected up nitrogen and helium fusion products to its surface. It shows 27% hydrogen at its surface.[6] It is estimated to have had an initial mass of 50 M☉ several million years ago.[4]
References
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27. doi:10.1888/0333750888/2862. ISBN 0333750888. Bibcode: 2000A&A...355L..27H.
- ↑ 4.0 4.1 4.2 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: 27–31. doi:10.1016/j.newast.2013.03.015. Bibcode: 2013NewA...25...27M.
- ↑ Maryeva, O. (2017). "A Study of Massive Stars with an Initial Mass of 50 M⊙ at Different Evolutionary Stages". Stars: From Collapse to Collapse 510: 192. Bibcode: 2017ASPC..510..192M.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Sota, A.; Maíz Apellániz, J.; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J. et al. (2019). "The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters". Astronomy & Astrophysics A57: 625. doi:10.1051/0004-6361/201834850. Bibcode: 2019A&A...625A..57H.
- ↑ 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. doi:10.26093/cds/vizier.1337. Bibcode: 2016yCat.1337....0G.
- ↑ Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
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