This is an old revision of this page, as edited by Lithopsian (talk | contribs) at 11:08, 1 May 2016 (Undo: if there are mistakes fix them. Don't just turn a useful article back into a stub.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 11:08, 1 May 2016 by Lithopsian (talk | contribs) (Undo: if there are mistakes fix them. Don't just turn a useful article back into a stub.)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff) WR 31a Credit: ESA/Hubble & NASA Acknowledgement: Judy Schmidt | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Carina |
| Right ascension | 10 53 59.586 |
| Declination | −60° 26′ 44.31″ |
| Apparent magnitude (V) | 10.85 |
| Characteristics | |
| Spectral type | WN11h |
| Variable type | cLBV |
| Astrometry | |
| Proper motion (μ) | RA: −3.6 mas/yr Dec.: 4.0 mas/yr |
| Distance | 8,000 pc |
| Absolute magnitude (MV) | −6.71 |
| Details | |
| Luminosity | 1,820,000 L☉ |
| Temperature | 30,200 K |
| Other designations | |
| WR 31a, Hen 3-519, IRAS 10520-6010, GSC2 S1113013697, 2MASS J10535958-6026444, AAVSO 1050-59 | |
| Database references | |
| SIMBAD | data |
WR 31a is a Wolf-Rayet star in the southern constellation of Carina that is surrounded by an expanding bubble blown by a powerful stellar wind. It is more commonly referred to as Hen 3-519, as it was known before being listed in the Catalogue of Wolf Rayet stars. It is a suspected, dormant, or post-Luminous Blue Variable (LBV).
Properties
The spectrum of Hen 3-519 contains both absorption and emission lines, intermediate between a hot supergiant and a Wolf-Rayet. On this basis it has been classified as Ofpe/WN9, a slash star. The same type of spectrum is also known as WN11, an extension of the traditional nitrogen sequence to cooler temperatures. It is a hydrogen-rich star, a young object rather than a highly evolved dying star.
The almost unique nature of WR 31a and its unusual spectrum make determination of its distance and physical properties very uncertain. It lies in a direction near the Carina Nebula and Carina OB2 but is thought to be more distant than either. AG Carinae, a confirmed LBV that has a WN11 spectrum at visual minimum, is found nearby in the constellation Carina and is calculated to be at a similar distance.
It is calculated that WR 31a had a mass of 45 M☉ when it was first formed.
Luminous Blue Variable
Hen 3-519 has been considered as a possible LBV almost since the term was first coined. It has never shown the characteristic LBV behaviour of an outburst with a drop in temperature accompanied by an increase in visual brightness at approximately constant luminosity, and its properties place it at the upperlimits of temperature and luminosity for such stars. However, it shares has many similarities to the confirmed LBV AG Carinae when it is at its minimum brightness and hottest temperature. It has been proposed that it has recently transitioned from a previous LBV state to a Wolf-Rayet state Van Genderen classified it as an ex or dormant LBV.
The Bubble
The nebula around WR 31a was first catalogued by Ellen Dorrit Hoffleit in 1953 as the planetary nebula Hf 39. Since 2013, the object has been considered not a planetary nebula but rather, an expanding shocked gas shell, formally classified as a Wolf–Rayet nebula, of the WR bubble type produced by strong WR winds sweeping up and heating material ejected during an earlier phase of the star's life.
The nebula has been calculated to contain 2 M☉ of ionised gas at an electron temperature of 8,000 K, most likely expelled from the star about 18,000 years ago. The dust in the bubble emits 6,500 times the total luminosity of the sun as infrared radiation, corresponding to a blackbody temperature of 115 K. The nebular material is expanding at 61 km/s, but the stellar wind velocity is 365 km/s, so the wind has swept up the circumstellar material into a thin shell some 2.4 parsecs across.
References
- ^ 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.
- ^ Toalá, J. A.; Guerrero, M. A.; Ramos-Larios, G.; Guzmán, V. (2015). "WISE morphological study of Wolf-Rayet nebulae". Astronomy & Astrophysics. 578: A66. arXiv:1503.06878. Bibcode:2015A&A...578A..66T. doi:10.1051/0004-6361/201525706.
- ^ Nazé, Y.; Rauw, G.; Hutsemékers, D. (2012). "The first X-ray survey of Galactic luminous blue variables". Astronomy & Astrophysics. 538: A47. arXiv:1111.6375. Bibcode:2012A&A...538A..47N. doi:10.1051/0004-6361/201118040.
- Van Der Hucht, Karel 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.
- ^ Smith, L. J.; Crowther, P. A.; Prinja, R. K. (1994). "A study of the luminous blue variable candidate He 3-519 and its surrounding nebula". Astronomy and Astrophysics (ISSN 0004-6361). 281: 833. Bibcode:1994A&A...281..833S.
- Crowther, Paul A. (2007). "Physical Properties of Wolf-Rayet Stars". Annual Review of Astronomy & Astrophysics. 45: 177. arXiv:astro-ph/0610356. Bibcode:2007ARA&A..45..177C. doi:10.1146/annurev.astro.45.051806.110615.
- ^ Davidson, Kris; Humphreys, Roberta M.; Hajian, Arsen; Terzian, Yervant (1993). "He 3-519 - A peculiar post-LBV, pre-WN star?". Astrophysical Journal. 411: 336. Bibcode:1993ApJ...411..336D. doi:10.1086/172833.
- Smith, Nathan; Tombleson, Ryan (2015). "Luminous blue variables are antisocial: Their isolation implies that they are kicked mass gainers in binary evolution". Monthly Notices of the Royal Astronomical Society. 447: 598. arXiv:1406.7431. Bibcode:2015MNRAS.447..598S. doi:10.1093/mnras/stu2430.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - Humphreys, Roberta M. (1989). "What are LBVs? - Their characteristics and role in the upper H-R diagram". IN: Physics of luminous blue variables; Proceedings of the 113th IAU Colloquium. Astrophysics and Space Science Library. 157: 3. Bibcode:1989ASSL..157....3H. doi:10.1007/978-94-009-1031-7_1. ISBN 978-94-010-6955-7.
- Crowther, Paul A.; Willis, Allan J. (1993). "Observations of the atmospheres and winds of O-stars, LBV's and Wolf-Rayet stars". Space Science Reviews. 66: 85. Bibcode:1993SSRv...66...85C. doi:10.1007/BF00771051.
- Van Genderen, A. M. (2001). "S Doradus variables in the Galaxy and the Magellanic Clouds". Astronomy and Astrophysics. 366 (2): 508. Bibcode:2001A&A...366..508V. doi:10.1051/0004-6361:20000022.
- Hoffleit, Dorrit (1953). "A preliminary survey of nebulosities and associated B-stars in Carina". Annals of Harvard College Observatory. 119: 37. Bibcode:1953AnHar.119...37H.
- Frew, D. J.; Bojicic, I. S.; Parker, Q. A. (2013). "A catalogue of integrated Hα fluxes for 1258 Galactic planetary nebulae". Monthly Notices of the Royal Astronomical Society. 431: 2. arXiv:1211.2505. Bibcode:2013MNRAS.431....2F. doi:10.1093/mnras/sts393.
{{cite journal}}: CS1 maint: unflagged free DOI (link)
| Constellation of Carina | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Stars |
| ||||||||||
| |||||||||||
| Star clusters |
| ||||||||||
| Nebulae |
| ||||||||||
| Galaxies |
| ||||||||||
| |||||||||||
| |||||||||||
 Category | |||||||||||