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| '''WR 31a''' is a ] in the southern constellation of ] that is surrounded by an expanding bubble nebula. 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-] (LBV). | |||
| '''WR 31a''' is a ] in the southern constellation of ] that is surrounded by an expanding optical blue bubble nebula<ref>{{cite web|url=https://www.nasa.gov/image-feature/goddard/2016/hubbles-blue-bubble|title=Hubble's Blue Bubble|work=NASA|accessdate=1 March 2016}}</ref> Some media sources have wrongly claimed this deep-sky object was recently discovered by the ],<ref>{{cite web|url=http://www.inquisitr.com/2841239/hubble-captures-blue-bubble-star-20-times-bigger-a-million-times-brighter-than-sun/|title=Hubble Captures "Blue Bubble' Star - 20 Times Bigger, a Million Times Brighter than the Sun's|work=Inquisitr|accessdate=2 March 2016}}</ref> but this nebula was originally found by ] in 1953 and designated as the ] '''Hf 39'''.<ref name="VizieR">{{cite web|url=http://vizier.u-strasbg.fr/viz-bin/VizieR-S?PN%20G288.9-00.8|title=VizieR|work=CDS|accessdate=2 March 2016}}</ref> Other planetary nebula catalogue names included, He 3-319, ESO 128-18, and Wray 15-682.<ref name="VizieR"/> | |||
| ==Properties== | |||
| ⚫ | Since 2013, the object has been considered not a planetary nebula but rather, an expanding gas shell, formally classified as a ] or WR nebula.<ref name=frew>{{cite journal|doi=10.1093/mnras/sts393|title=A catalogue of integrated Hα fluxes for 1258 Galactic planetary nebulae|journal=Monthly Notices of the Royal Astronomical Society|volume=431|pages=2|year=2013|last1=Frew|first1=D. J.|last2=Bojicic|first2=I. S.|last3=Parker|first3=Q. A.|bibcode=2013MNRAS.431....2F}}</ref> Its observed expansion velocity is 365 km.s<sup>−1</sup>, estimated to be some 2.4 parsecs across.<ref name=toala/> | ||
| The spectrum of Hen 3-519 contains both absorption and emission lines, intermediate between a hot ] 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.<ref name=crowther>{{cite journal|bibcode=2007ARA&A..45..177C|arxiv=astro-ph/0610356}}</ref> | |||
| 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 ] and ] but is thought to be more distant than either. It is close to ], another highly luminous WNL star and is calculated to be at a similar distance. | |||
| Its central highly luminous star (TYC 8928-1166-1) is invisible to the naked-eye, shining at 10.85V magnitude,<ref>{{cite web|url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=WR+31a&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id|title=SIMBAD|work=CDS|accessdate=2 March 2016}}</ref> whose spectral type is WN11h.<ref name=toala/> Mass of the central star is estimated to be at least 20 times that of the Sun, and it will likely become a ] type II event in the future.<ref>{{cite web|url=https://www.spacetelescope.org/images/potw1608a/|title=Blue bubble in Carina|work=NASA|accessdate=2 March 2016}}</ref> Distance is estimated to be about 9,200 parsecs or 30,000 light-years. | |||
| ==Luminous Blue Variable== | |||
| Hen 3-519 has been considered as a possible LBV almost since the term was first coined, although it has never shown the characteristic LBV variability. Its properties place it at the limit of temperature and luminosity for such stars, although comparable to the confirmed LBV AG Carinae.<ref name=davidson>{{cite journal|bibcode=1993ApJ...411..336D}}</ref> | |||
| ==Bubble Nebula== | |||
| ⚫ | The nebula around WR 31a was first catalogued by ] in 1953 as the ] '''Hf 39'''. Since 2013, the object has been considered not a planetary nebula but rather, an expanding shocked gas shell, formally classified as a ] or WR nebula.<ref name=frew>{{cite journal|doi=10.1093/mnras/sts393|title=A catalogue of integrated Hα fluxes for 1258 Galactic planetary nebulae|journal=Monthly Notices of the Royal Astronomical Society|volume=431|pages=2|year=2013|last1=Frew|first1=D. J.|last2=Bojicic|first2=I. S.|last3=Parker|first3=Q. A.|bibcode=2013MNRAS.431....2F}}</ref> Its observed expansion velocity is 365 km.s<sup>−1</sup>, estimated to be some 2.4 parsecs across.<ref name=toala/> | ||
| ==References== | ==References== | ||
Revision as of 22:30, 10 March 2016
 WR 31a Credit: ESA/Hubble & NASA Acknowledgement: Judy Schmidt | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cassiopeia |
| 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 | |
| Mass | 45 M☉ |
| 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 nebula. 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. It is close to AG Carinae, another highly luminous WNL star and is calculated to be at a similar distance.
Luminous Blue Variable
Hen 3-519 has been considered as a possible LBV almost since the term was first coined, although it has never shown the characteristic LBV variability. Its properties place it at the limit of temperature and luminosity for such stars, although comparable to the confirmed LBV AG Carinae.
Bubble Nebula
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 or WR nebula. Its observed expansion velocity is 365 km.s, estimated to be 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, 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) - . arXiv:astro-ph/0610356. Bibcode:2007ARA&A..45..177C.
{{cite journal}}: Cite journal requires|journal=(help); Missing or empty|title=(help) - . Bibcode:1993ApJ...411..336D.
{{cite journal}}: Cite journal requires|journal=(help); Missing or empty|title=(help) - 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. Bibcode:2013MNRAS.431....2F. doi:10.1093/mnras/sts393.
{{cite journal}}: CS1 maint: unflagged free DOI (link)