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| ] created by a powerful ] impacting material expelled during earlier stages of the star's life (ESA/Hubble & NASA Acknowledgement: Judy Schmidt)]] | |||
| {{Starbox begin | |||
| | name = WR 31a | |||
| }} | |||
| {{Starbox image | |||
| | image=] | |||
| | caption=WR 31a | |||
| | credit=ESA/Hubble & NASA Acknowledgement: Judy Schmidt | |||
| }} | |||
| {{Starbox observe | |||
| | epoch = J2000.0 | |||
| | constell = ] | |||
| | ra = {{RA|10|53|59.586}}<ref name=tycho2>{{cite journal|bibcode=2000A&A...355L..27H|title=The Tycho-2 catalogue of the 2.5 million brightest stars|journal=Astronomy and Astrophysics|volume=355|pages=L27|author1=Høg|first1=E.|last2=Fabricius|first2=C.|last3=Makarov|first3=V. V.|last4=Urban|first4=S.|last5=Corbin|first5=T.|last6=Wycoff|first6=G.|last7=Bastian|first7=U.|last8=Schwekendiek|first8=P.|last9=Wicenec|first9=A.|year=2000}}</ref> | |||
| | dec = {{DEC|−60|26|44.31}}<ref name=tycho2/> | |||
| | appmag_v = 10.85<ref name=tycho2/> | |||
| }} | |||
| {{Starbox character | |||
| | class = WN11h<ref name=toala/> | |||
| | b-v = | |||
| | u-b = | |||
| | variable=]<ref name=naze>{{cite journal|bibcode=2012A&A...538A..47N|arxiv=1111.6375|title=The first X-ray survey of Galactic luminous blue variables|journal=Astronomy & Astrophysics|volume=538|pages=A47|author1=Nazé|first1=Y.|last2=Rauw|first2=G.|last3=Hutsemékers|first3=D.|year=2012|doi=10.1051/0004-6361/201118040}}</ref> | |||
| }} | |||
| {{Starbox astrometry | |||
| | radial_v = | |||
| | prop_mo_ra = −3.6<ref name=tycho2/> | |||
| | prop_mo_dec = 4.0<ref name=tycho2/> | |||
| | parallax = | |||
| | p_error = | |||
| | parallax_footnote = | |||
| | dist_pc = 8,000<ref name=toala>{{cite journal|bibcode=2015A&A...578A..66T|arxiv=1503.06878|title=WISE morphological study of Wolf-Rayet nebulae|journal=Astronomy & Astrophysics|volume=578|pages=A66|author1=Toalá|first1=J. A.|last2=Guerrero|first2=M. A.|last3=Ramos-Larios|first3=G.|last4=Guzmán|first4=V.|year=2015|doi=10.1051/0004-6361/201525706}}</ref> | |||
| | absmag_v = −6.71<ref name=wr>{{cite journal|bibcode=2001NewAR..45..135V|title=The VIIth catalogue of galactic Wolf-Rayet stars|journal=New Astronomy Reviews|volume=45|issue=3|pages=135|author1=Van Der Hucht|first1=Karel A.|year=2001|doi=10.1016/S1387-6473(00)00112-3}}</ref> | |||
| }} | |||
| {{Starbox detail | |||
| | source=<ref name=naze/> | |||
| | mass = | |||
| | radius = | |||
| | luminosity = 1,820,000 | |||
| | temperature = 30,200 | |||
| | metallicity_fe = | |||
| | gravity = | |||
| | age = | |||
| }} | |||
| {{Starbox catalog | |||
| | names = ] 31a, ] 3-519, ] 10520-6010, ] S1113013697, ] J10535958-6026444, ] 1050-59 | |||
| }} | |||
| {{Starbox reference | |||
| | Simbad = WR31a | |||
| }} | |||
| {{Starbox end}} | |||
| '''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"/> | |||
| '''WR 31a''' is a ] in the southern constellation of ] that is surrounded by an expanding bubble blown by a powerful ]. 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). | |||
| 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=wise>{{Cite journal|arxiv=1503.06878v1|last1= Toalá|first1= J. A.|title= WISE morphological study of Wolf-Rayet nebulae|journal= Astronomy & Astrophysics|volume= 578|pages= A66|last2= Guerrero|first2= M. A.|last3= Ramos-Larios|first3= G.|last4= Guzmán|first4= V.|year= 2015|doi= 10.1051/0004-6361/201525706}}</ref> | |||
| ==Properties== | |||
| 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.<ref name=smith1994>{{cite journal|bibcode=1994A&A...281..833S|title=A study of the luminous blue variable candidate He 3-519 and its surrounding nebula|journal=Astronomy and Astrophysics (ISSN 0004-6361)|volume=281|pages=833|author1=Smith|first1=L. J.|last2=Crowther|first2=P. A.|last3=Prinja|first3=R. K.|year=1994}}</ref> 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|title=Physical Properties of Wolf-Rayet Stars|journal=Annual Review of Astronomy & Astrophysics|volume=45|pages=177|author1=Crowther|first1=Paul A.|year=2007|doi=10.1146/annurev.astro.45.051806.110615}}</ref> | |||
| 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="wise" /> 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. | |||
| 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. ], 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.<ref name=davidson/> | |||
| It is calculated that WR 31a had a mass of {{solar mass|45}} when it was first formed.<ref name=smith>{{cite journal|bibcode=2015MNRAS.447..598S|arxiv=1406.7431|title=Luminous blue variables are antisocial: Their isolation implies that they are kicked mass gainers in binary evolution|journal=Monthly Notices of the Royal Astronomical Society|volume=447|pages=598|author1=Smith|first1=Nathan|last2=Tombleson|first2=Ryan|year=2015|doi=10.1093/mnras/stu2430}}</ref> | |||
| ==Luminous Blue Variable== | |||
| Hen 3-519 has been considered as a possible LBV almost since the term was first coined.<ref name=humphreys>{{cite journal|bibcode=1989ASSL..157....3H|title=What are LBVs? - Their characteristics and role in the upper H-R diagram|journal=IN: Physics of luminous blue variables; Proceedings of the 113th IAU Colloquium|volume=157|pages=3|author1=Humphreys|first1=Roberta M.|year=1989|doi=10.1007/978-94-009-1031-7_1|series=Astrophysics and Space Science Library|isbn=978-94-010-6955-7}}</ref><ref name=crowther1993>{{cite journal|bibcode=1993SSRv...66...85C|title=Observations of the atmospheres and winds of O-stars, LBV's and Wolf-Rayet stars|journal=Space Science Reviews|volume=66|pages=85|author1=Crowther|first1=Paul A.|last2=Willis|first2=Allan J.|year=1993|doi=10.1007/BF00771051}}</ref> 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<ref name=smith1994/><ref name=davidson>{{cite journal|bibcode=1993ApJ...411..336D|title=He 3-519 - A peculiar post-LBV, pre-WN star?|journal=Astrophysical Journal|volume=411|pages=336|author1=Davidson|first1=Kris|last2=Humphreys|first2=Roberta M.|last3=Hajian|first3=Arsen|last4=Terzian|first4=Yervant|year=1993|doi=10.1086/172833}}</ref> Van Genderen classified it as an ex or dormant LBV.<ref name=vangenderen2001>{{cite journal|bibcode=2001A&A...366..508V|title=S Doradus variables in the Galaxy and the Magellanic Clouds|journal=Astronomy and Astrophysics|volume=366|issue=2|pages=508|author1=Van Genderen|first1=A. M.|year=2001|doi=10.1051/0004-6361:20000022}}</ref> | |||
| ==The Bubble== | |||
| The nebula around WR 31a was first catalogued by ] in 1953 as the ] '''Hf 39'''.<ref name=hoffleit>{{cite journal|bibcode=1953AnHar.119...37H|title=A preliminary survey of nebulosities and associated B-stars in Carina|journal=Annals of Harvard College Observatory|volume=119|pages=37|author1=Hoffleit|first1=Dorrit|year=1953}}</ref> Since 2013, the object has been considered not a planetary nebula but rather, an expanding shocked gas shell, formally classified as a ],<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|arxiv = 1211.2505 }}</ref> 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.<ref name=toala/> | |||
| The nebula has been calculated to contain {{solar mass|2}} of ionised gas at an ] 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 ] radiation, corresponding to a ] of 115 K.<ref name=smith1994/> 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.<ref name=toala/> | |||
| ==References== | ==References== | ||
| {{Reflist}} | {{Reflist}} | ||
| {{Stars of Carina}} | |||
| ] | ] | ||
| ] | ] | ||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
Revision as of 02:57, 30 April 2016
WR 31a is a Wolf-Rayet star in the southern constellation of Carina that is surrounded by an expanding optical blue bubble nebula Some media sources have wrongly claimed this deep-sky object was recently discovered by the Hubble Space Telescope, but this nebula was originally found by Ellen Dorrit Hoffleit in 1953 and designated as the planetary nebula Hf 39. Other planetary nebula catalogue names included, He 3-319, ESO 128-18, and Wray 15-682.
Since 2013, the object has been considered not a planetary nebula but rather, an expanding 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.
Its central highly luminous star (TYC 8928-1166-1) is invisible to the naked-eye, shining at 10.85V magnitude, whose spectral type is WN11h. Mass of the central star is estimated to be at least 20 times that of the Sun, and it will likely become a supernova type II event in the future. Distance is estimated to be about 9,200 parsecs or 30,000 light-years.
References
- "Hubble's Blue Bubble". NASA. Retrieved 1 March 2016.
- "Hubble Captures "Blue Bubble' Star - 20 Times Bigger, a Million Times Brighter than the Sun's". Inquisitr. Retrieved 2 March 2016.
- ^ "VizieR". CDS. Retrieved 2 March 2016.
- 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) - ^ Toalá, J. A.; Guerrero, M. A.; Ramos-Larios, G.; Guzmán, V. (2015). "WISE morphological study of Wolf-Rayet nebulae". Astronomy & Astrophysics. 578: A66. arXiv:1503.06878v1. doi:10.1051/0004-6361/201525706.
- "SIMBAD". CDS. Retrieved 2 March 2016.
- "Blue bubble in Carina". NASA. Retrieved 2 March 2016.