Misplaced Pages

WR 31a: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively← Previous editContent deleted Content addedVisualWikitext
Revision as of 17:14, 22 April 2016 editLithopsian (talk | contribs)Autopatrolled, Extended confirmed users, New page reviewers68,623 edits Clarify initial mass← Previous edit Latest revision as of 12:01, 25 September 2024 edit undoPopePompus (talk | contribs)Autopatrolled, Extended confirmed users, New page reviewers11,902 edits Added a light curve 
(138 intermediate revisions by 26 users not shown)
Line 1: Line 1:
{{Short description|Wolf Rayet star in the constellation Carina}}
{{Use dmy dates|date=July 2017}}
{{Starbox begin {{Starbox begin
| name = WR 31a | name = WR 31a
}} }}
{{Starbox image {{Starbox image
| image=] | image = ]
| caption = WR 31a is surrounded by a blue bubble nebula created by a powerful ] impacting material expelled during earlier stages of the star's life.
| caption=WR 31a
| credit=ESA/Hubble & NASA Acknowledgement: Judy Schmidt | credit = ESA/Hubble & NASA; Acknowledgement: Judy Schmidt
}}
{{Starbox observe
| epoch = J2000.0
| constell = ]
| ra = {{RA|10|53|59.5777}}<ref name=dr3/>
| dec = {{DEC|−60|26|44.361}}<ref name=dr3/>
| appmag_v = 10.85<ref name=tycho2/>
}}
{{Starbox character
| type = ]
| class = WN11h<ref name=toala/>
| appmag_1_passband = B
| appmag_1 = {{val|11.64|0.10}}
| appmag_2_passband = V
| appmag_2 = {{val|10.85|0.08}}
| appmag_3_passband = R
| appmag_3 = {{val|10.56|0.02}}
| appmag_4_passband = G
| appmag_4 = {{val|10.033|0.004}}
| appmag_5_passband = J
| appmag_5 = {{val|7.323|0.024}}
| appmag_6_passband = H
| appmag_6 = {{val|6.72|0.05}}
| appmag_7_passband = K
| appmag_7 = {{val|6.097|0.021}}
| appmag_8_passband = g
| appmag_8 = {{val|11.53|0.32}}
| r-i = 0.5
| v-r = 0.29
| b-v = 0.79
| j-h = 0.603
| j-k = 1.226
| variable = ]<ref name=naze/><ref name=smith2015/>
}} }}
{{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|&minus;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 {{Starbox astrometry
| radial_v = | radial_v =
| prop_mo_ra = −3.6<ref name=tycho2/> | prop_mo_ra = −5.890<ref name=dr3/>
| prop_mo_dec = 4.0<ref name=tycho2/> | prop_mo_dec = 2.842<ref name=dr3/>
| parallax = | parallax = 0.1152
| p_error = | p_error = 0.0131
| parallax_footnote = | parallax_footnote=<ref name=dr3/>
| dist_ly =
| 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>
| dist_pc =
| absmag_v = &minus;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>
| absmag_v = −6.71<ref name=wr/>
}}
}}
{{Starbox detail
{{Starbox detail
| source=<ref name=naze/>
| mass = | source =
| mass = {{val|17|7|4}}<ref name=smith/>
| radius =
| radius = {{val|29.8|11.9|6.1}}<ref name=smith/>
| luminosity = 1,820,000
| luminosity = {{nowrap|1,820,000<ref name=vangenderen/>}}
| temperature = 30,200
| temperature = {{nowrap|30,200 (1985–1992)<ref name=vangenderen/>}} {{nowrap|27,500 (1991)<ref name=smith/>}}
| metallicity_fe =
| metallicity_fe =
| gravity =
| age = | gravity =
| age =
}}
}}
{{Starbox catalog {{Starbox catalog
| names = {{nowrap|] 31a,}} {{nowrap|] 3-519,}} {{nowrap|He 3-519,<ref name=smith/>}} {{nowrap|] J10535958-6026444,}} {{nowrap|] DR1 5338229111491506304,}} {{nowrap|] 08958-01166,}} {{nowrap|] S1113013697,}} {{nowrap|] 5308747,}} {{nowrap|] 148-066854,}} {{nowrap|] 10520-6010,}} {{nowrap|] 8928-1166-1,}} {{nowrap|] 1050–59,}} {{nowrap|] G288.9347-00.8046}}
| names = ]&nbsp;31a, ]&nbsp;3-519, ]&nbsp;10520-6010, ]&nbsp;S1113013697, ]&nbsp;J10535958-6026444, ]&nbsp;1050-59
}} }}
{{Starbox reference {{Starbox reference
| Simbad = 6+Cas | Simbad = WR_31a
}} }}
{{Starbox end}} {{Starbox end}}


'''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''', commonly referred to as '''Hen 3-519''', is a ] (WR) star in the southern constellation of ] that is surrounded by an expanding ]. It is not a classical old stripped-envelope WR star, but a young massive star which still has some hydrogen left in its atmosphere.

== History of observations ==
WR 31a was first published in 1952 as one of six peculiar ] stars, but not given a designation at that time. It was described as having numerous ] lines with unusually broad emission components.<ref name=henize>{{cite journal |bibcode=1952ApJ...115..133H |title=Six Peculiar Hα-Emission Stars |journal=Astrophysical Journal |volume=115 |pages=133 |last1=Henize |first1=Karl G. |year=1952 |doi=10.1086/145522|doi-access=free }}</ref> A year later it was listed as being associated with nebulosity, at the time thought to be a planetary nebula.<ref name=hoffleit/>

In 1976, it was included in a catalogue of southern emission-line stars, the third catalogue of emission objects compiled by ]. The designation {{nowrap|Hen 3-519}}, sometimes {{nowrap|He 3-519}}, was adopted as the most common identifier for this star.<ref name=hen>{{cite journal |bibcode=1976ApJS...30..491H |title=Observations of southern emission-line stars |journal=Astrophysical Journal Supplement Series |volume=30 |pages=491 |last1=Henize |first1=K. G. |year=1976 |doi=10.1086/190369|doi-access=free }}</ref> In 2001, it was listed in The Seventh Catalogue of Galactic Wolf-Rayet stars as entry 31a,<ref name=wr/> but it is still frequently called {{nowrap|Hen 3-519}}.<ref name=smith2015 /><ref name=naze />

In 1994, WR 31a was first described as a candidate ] (cLBV) after a detailed ] study with the ].<ref name=smith />

Measurements of its ], published in 2017 as a result of the '']'' mission, suggested a much closer (6,500 ]; 2,000 ]) distance to {{nowrap|WR 31a}} as well as to its neighbor, the luminous blue variable ]. It was thought that, if this distance was confirmed by ''Gaia''{{'s}} second data release (DR2) in 2018, this would mean both stars were much less luminous than previously thought, and both may instead be former ] stars.<ref name=SmithN2017>{{cite journal |title=The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 are Much Closer than Previously Assumed |journal=The Astronomical Journal |first1=Nathan |last1=Smith |first2=Keivan G. |last2=Stassun |volume=153 |issue=3 |at=125 |date=March 2017 |doi=10.3847/1538-3881/aa5d0c |bibcode=2017AJ....153..125S |arxiv=1610.06522|s2cid=119296636 |doi-access=free }}</ref> However, ] returned a parallax of {{val|0.0418|0.0299|ul=mas}}; using ], Smith ''et al.'' (2018) calculated its distance to be {{val|31,200|8,500|6,000|fmt=commas|ul=ly}} ({{val|9,570|2,600|1,850|fmt=commas|ul=pc}}).<ref name=NSmith2018>{{cite journal |title=On the Gaia DR2 distances for Galactic Luminous Blue Variables |arxiv=1805.03298 |first1=Nathan |last1=Smith |first2=Mojgan |last2=Aghakhanloo |first3=Jeremiah W. |last3=Murphy |first4=Keivan G. |last4=Stassun |first5=Maria R. |last5=Drout |first6=Jose H. |last6=Groh |journal=Monthly Notices of the Royal Astronomical Society |year=2019 |volume=488 |issue=2 |pages=1760–1778 |display-authors=1 |doi=10.1093/mnras/stz1712 |doi-access=free |bibcode=2019MNRAS.488.1760S |s2cid=119267371 }}</ref> ] lists a parallax of {{val|0.1152|0.0156|u=mas}}, again indicating a large distance.<ref name=dr3/> A statistical analysis leads to a distance of {{val|7,315|993|935|ul=pc|fmt=commas}}.<ref name=bailer-jones/>

== Blue bubble ==
WR 31a is surrounded by a ] nearly {{convert|8|ly|pc|spell=in}} wide. The ] (HST) has captured a striking image of the nebula, rendering it as a thin blue bubble. In this false colour image, the blue colours represents red visible light (605&nbsp;nm), while orange-red colours represent near ] radiation at 814&nbsp;nm.<ref>{{cite web |url=https://www.nasa.gov/image-feature/goddard/2016/hubbles-blue-bubble |title=Hubble's Blue Bubble |work=NASA |access-date=1 March 2016|date=2016-02-26 }}</ref> Some media sources have wrongly claimed this deep-sky object was recently discovered by the HST,<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 |date=29 February 2016 |access-date=2 March 2016}}</ref> but this nebula was originally found by ] in 1953 and designated 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 |last1=Hoffleit |first1=Dorrit |year=1953}}</ref> Other planetary nebula catalogue names include ESO 128-18 and Wray 15-682.<ref name=hoffleit />

Since 2013, the nebula has been considered not as a planetary nebula, but rather as a much larger 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 |issue=1 |pages=2–26 |year=2013 |last1=Frew |first1=D. J. |last2=Bojicic |first2=I. S. |last3=Parker |first3=Q. A. |doi-access=free |bibcode=2013MNRAS.431....2F |arxiv=1211.2505|s2cid=119174103 }}</ref> Its observed expansion velocity is {{convert|365|km/s|mi/s|abbr=on}}, and is estimated to be some {{convert|2.4|pc|ly}} across.<ref name=wise>{{Cite journal |arxiv=1503.06878 |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 |bibcode=2015A&A...578A..66T|s2cid=55776698 }}</ref> The dynamical age of the nebula is estimated at 18,000 years and the total mass of ionised gas at {{solar mass|2–3}}.<ref name=smith />

== Properties ==
WR 31a itself, the highly luminous central star of the nebula, is invisible to the naked-eye at magnitude 10.85V. It has a spectral classification of WN11h, indicating a WR star with strong N{{smallcaps|ii}} emission but no N{{smallcaps|iii}} emission, and with hydrogen features visible in the spectrum.<ref name=wise/> The spectral classification WN11 was created for this star and ] since they did not fit into any existing spectral type and appeared to constitute an extension of the WR nitrogen sequence to cooler temperatures.<ref name=smith>{{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 |volume=281 |issue=3 |pages=833–854 |last1=Smith |first1=L. J. |last2=Crowther |first2=P. A. |last3=Prinja |first3=R. K. |year=1994}}</ref> The progenitor's mass of the central star is estimated to have been about 45 times that of the Sun,<ref name=smith2015>{{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 |issue=1 |pages=598–617 |last1=Smith |first1=Nathan |last2=Tombleson |first2=Ryan |year=2015 |doi=10.1093/mnras/stu2430|doi-access=free |s2cid=119284620 }}</ref> and this massive star will likely explode as a ] in the future.<ref name="Blue bubble in Carina">{{cite web |url=https://www.spacetelescope.org/images/potw1608a/ |title=Blue bubble in Carina |work=NASA |access-date=2 March 2016}}</ref>

The spectrum of WR 31a shows ]s, most strongly on the dominant H{{smallcaps|i}}, He{{smallcaps|i}}, and N{{smallcaps|ii}} lines. These profiles may show dramatic changes on a timescale of weeks, with the absorption components of the lines sometimes disappearing completely.<ref name=smith/>

== Variability ==
] ] for WR 31a, plotted from ] data<ref name="ASAS-SN"/>]]
No significant brightness changes have been detected in WR 31a, but it has been listed as a candidate luminous blue variable because of its luminosity, temperature, and mass loss properties.<ref name=smith /> Van Genderen catalogued it as a dormant or ex-LBV because of the lack of characteristic LBV variations.<ref name=vangenderen>{{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=508–531 |last1=Van Genderen |first1=A. M. |year=2001 |doi=10.1051/0004-6361:20000022|doi-access=free }}</ref> Possible small brightness changes have been seen in ] (ASAS) data,<ref name=asas>{{cite journal |bibcode=2002AcA....52..397P |arxiv=astro-ph/0210283 |title=The All Sky Automated Survey. Catalog of Variable Stars. I. 0 h – 6 h ''Quarter'' of the Southern Hemisphere |journal=Acta Astronomica |volume=52 |pages=397–427 |last1=Pojmanski |first1=G. |year=2002}}</ref> WR 31a is included as a variable star in the International Variable Star Index,<ref name=vsx>{{cite web |url=https://www.aavso.org/vsx/index.php?view=detail.top&revid=256789 |title=Hen 3-519 |publisher=] |work=International Variable Star Index |access-date=30 September 2016 |date=4 January 2010}}</ref> although not in the ].<ref name=gcvs>{{cite journal |bibcode=2009yCat....102025S |title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013) |journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S |volume=1 |display-authors=etal |last1=Samus |first1=N. N. |last2=Durlevich |first2=O. V. |year=2009}}</ref>

== References ==
{{Reflist|refs=

<ref name=tycho2>{{cite book |bibcode=2000A&A...355L..27H |title=The Tycho-2 catalogue of the 2.5&nbsp;million brightest stars |journal=Astronomy and Astrophysics |volume=355 |pages=L27 |last1=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 |doi=10.1888/0333750888/2862|isbn=978-0333750889 }}</ref>

<ref name="ASAS-SN">{{cite web |url=https://asas-sn.osu.edu/variables/lookup |website=ASAS-SN Variable Stars Database|title=ASAS-SN Variable Stars Database|publisher=ASAS-SN |access-date=25 September 2024}}</ref>

<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 |last1=Nazé |first1=Y. |last2=Rauw |first2=G. |last3=Hutsemékers |first3=D. |year=2012 |doi=10.1051/0004-6361/201118040|s2cid=43688343 }}</ref>

<!-- <ref name=dr1>{{cite journal |bibcode=2016yCat.1337....0G |title=VizieR Online Data Catalog: Gaia DR1 |journal=Astronomy and Astrophysics |author=Gaia Collaboration |date=2016}}</ref> -->


<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 |last1=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|s2cid=55776698 }}</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. 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>


<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=135–232 |last1=Van Der Hucht |first1=Karel A. |author-link1=Karel van der Hucht|year=2001 |doi=10.1016/S1387-6473(00)00112-3}}</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 ], a confirmed LBV that has a WN11 spectrum at visual minimum and is calculated to be at a similar distance.


<!-- <ref name=gaia>{{cite journal |bibcode=2016A&A...595A...2G |title=Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties |journal=Astronomy and Astrophysics |last1=Brown |first1=A. G. A. |last2=Vallenari |first2=A. |last3=Prusti |first3=T. |last4=de Bruijne |first4=J. |last5=Mignard |first5=F. |display-authors=etal |date=2016 |arxiv=1609.04172 |doi=10.1051/0004-6361/201629512 |volume=595 |pages=A2}}</ref> -->
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>


<ref name=bailer-jones>{{cite journal |bibcode=2021AJ....161..147B |title=Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3 |last1=Bailer-Jones |first1=C. A. L. |last2=Rybizki |first2=J. |last3=Fouesneau |first3=M. |last4=Demleitner |first4=M. |last5=Andrae |first5=R. |journal=The Astronomical Journal |year=2021 |volume=161 |issue=3 |page=147 |doi=10.3847/1538-3881/abd806 |arxiv=2012.05220 |s2cid=228063812 |doi-access=free }}</ref>
==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|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>


<ref name=dr3>{{cite Gaia DR3|5338229115839425664}}</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&nbsp;km.s<sup>−1</sup>, estimated to be some 2.4 parsecs across.<ref name=toala/>


}} <!-- end of reflist -->
==References==
{{Reflist}}


{{Stars of Carina}} {{Stars of Carina}}


{{DEFAULTSORT:WR 31a}}
] ]
] ]
]
] ]
] ]
]

Latest revision as of 12:01, 25 September 2024

Wolf Rayet star in the constellation Carina

WR 31a

WR 31a is surrounded by a blue bubble nebula created by a powerful stellar wind impacting material expelled during earlier stages of the star's life.
Credit: ESA/Hubble & NASA; Acknowledgement: Judy Schmidt
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Carina
Right ascension 10 53 59.5777
Declination −60° 26′ 44.361″
Apparent magnitude (V) 10.85
Characteristics
Evolutionary stage Wolf–Rayet
Spectral type WN11h
Apparent magnitude (B) 11.64±0.10
Apparent magnitude (V) 10.85±0.08
Apparent magnitude (R) 10.56±0.02
Apparent magnitude (G) 10.033±0.004
Apparent magnitude (J) 7.323±0.024
Apparent magnitude (H) 6.72±0.05
Apparent magnitude (K) 6.097±0.021
Apparent magnitude (g) 11.53±0.32
B−V color index 0.79
V−R color index 0.29
R−I color index 0.5
J−H color index 0.603
J−K color index 1.226
Variable type cLBV
Astrometry
Proper motion (μ) RA: −5.890 mas/yr
Dec.: 2.842 mas/yr
Parallax (π)0.1152 ± 0.0131 mas
Distanceapprox. 28,000 ly
(approx. 8,700 pc)
Absolute magnitude (MV)−6.71
Details
Mass17+7
−4 M☉
Radius29.8+11.9
−6.1 R☉
Luminosity1,820,000 L☉
Temperature30,200 (1985–1992) 27,500 (1991) K
Other designations
WR 31a, Hen 3-519, He 3-519, 2MASS J10535958-6026444, Gaia DR1 5338229111491506304, GSC 08958-01166, GSC2 S1113013697, UCAC2 5308747, UCAC4 148-066854, IRAS 10520-6010, TYC 8928-1166-1, AAVSO 1050–59, MSX5C G288.9347-00.8046
Database references
SIMBADdata

WR 31a, commonly referred to as Hen 3-519, is a Wolf–Rayet (WR) star in the southern constellation of Carina that is surrounded by an expanding Wolf–Rayet nebula. It is not a classical old stripped-envelope WR star, but a young massive star which still has some hydrogen left in its atmosphere.

History of observations

WR 31a was first published in 1952 as one of six peculiar emission line stars, but not given a designation at that time. It was described as having numerous P Cygni type lines with unusually broad emission components. A year later it was listed as being associated with nebulosity, at the time thought to be a planetary nebula.

In 1976, it was included in a catalogue of southern emission-line stars, the third catalogue of emission objects compiled by Karl Gordon Henize. The designation Hen 3-519, sometimes He 3-519, was adopted as the most common identifier for this star. In 2001, it was listed in The Seventh Catalogue of Galactic Wolf-Rayet stars as entry 31a, but it is still frequently called Hen 3-519.

In 1994, WR 31a was first described as a candidate luminous blue variable (cLBV) after a detailed spectrographic study with the Anglo-Australian Telescope.

Measurements of its parallax, published in 2017 as a result of the Gaia mission, suggested a much closer (6,500 light-year; 2,000 parsec) distance to WR 31a as well as to its neighbor, the luminous blue variable AG Carinae. It was thought that, if this distance was confirmed by Gaia's second data release (DR2) in 2018, this would mean both stars were much less luminous than previously thought, and both may instead be former red supergiant stars. However, Gaia Data Release 2 returned a parallax of 0.0418±0.0299 mas; using Bayesian inference, Smith et al. (2018) calculated its distance to be 31,200+8,500
−6,000 ly (9,570+2,600
−1,850 pc). Gaia Data Release 3 lists a parallax of 0.1152±0.0156 mas, again indicating a large distance. A statistical analysis leads to a distance of 7,315+993
−935 pc.

Blue bubble

WR 31a is surrounded by a shell of ionised gas nearly eight light-years (2.5 pc) wide. The Hubble Space Telescope (HST) has captured a striking image of the nebula, rendering it as a thin blue bubble. In this false colour image, the blue colours represents red visible light (605 nm), while orange-red colours represent near infrared radiation at 814 nm. Some media sources have wrongly claimed this deep-sky object was recently discovered by the HST, 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 include ESO 128-18 and Wray 15-682.

Since 2013, the nebula has been considered not as a planetary nebula, but rather as a much larger expanding gas shell, formally classified as a Wolf–Rayet nebula or WR nebula. Its observed expansion velocity is 365 km/s (227 mi/s), and is estimated to be some 2.4 parsecs (7.8 ly) across. The dynamical age of the nebula is estimated at 18,000 years and the total mass of ionised gas at 2–3 M☉.

Properties

WR 31a itself, the highly luminous central star of the nebula, is invisible to the naked-eye at magnitude 10.85V. It has a spectral classification of WN11h, indicating a WR star with strong Nii emission but no Niii emission, and with hydrogen features visible in the spectrum. The spectral classification WN11 was created for this star and AG Carinae since they did not fit into any existing spectral type and appeared to constitute an extension of the WR nitrogen sequence to cooler temperatures. The progenitor's mass of the central star is estimated to have been about 45 times that of the Sun, and this massive star will likely explode as a supernova in the future.

The spectrum of WR 31a shows P Cygni profiles, most strongly on the dominant Hi, Hei, and Nii lines. These profiles may show dramatic changes on a timescale of weeks, with the absorption components of the lines sometimes disappearing completely.

Variability

A visual band light curve for WR 31a, plotted from ASAS-SN data

No significant brightness changes have been detected in WR 31a, but it has been listed as a candidate luminous blue variable because of its luminosity, temperature, and mass loss properties. Van Genderen catalogued it as a dormant or ex-LBV because of the lack of characteristic LBV variations. Possible small brightness changes have been seen in All Sky Automated Survey (ASAS) data, WR 31a is included as a variable star in the International Variable Star Index, although not in the General Catalogue of Variable Stars.

References

  1. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  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. Vol. 355. pp. L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN 978-0333750889. {{cite book}}: |journal= ignored (help)
  3. 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. S2CID 55776698.
  4. ^ 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. S2CID 43688343.
  5. ^ 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 (1): 598–617. arXiv:1406.7431. Bibcode:2015MNRAS.447..598S. doi:10.1093/mnras/stu2430. S2CID 119284620.
  6. ^ Van Der Hucht, Karel A. (2001). "The VIIth catalogue of galactic Wolf–Rayet stars". New Astronomy Reviews. 45 (3): 135–232. Bibcode:2001NewAR..45..135V. doi:10.1016/S1387-6473(00)00112-3.
  7. ^ 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. 281 (3): 833–854. Bibcode:1994A&A...281..833S.
  8. ^ Van Genderen, A. M. (2001). "S Doradus variables in the Galaxy and the Magellanic Clouds". Astronomy and Astrophysics. 366 (2): 508–531. Bibcode:2001A&A...366..508V. doi:10.1051/0004-6361:20000022.Vizie database entry
  9. Henize, Karl G. (1952). "Six Peculiar Hα-Emission Stars". Astrophysical Journal. 115: 133. Bibcode:1952ApJ...115..133H. doi:10.1086/145522.
  10. ^ 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.
  11. Henize, K. G. (1976). "Observations of southern emission-line stars". Astrophysical Journal Supplement Series. 30: 491. Bibcode:1976ApJS...30..491H. doi:10.1086/190369.
  12. Smith, Nathan; Stassun, Keivan G. (March 2017). "The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 are Much Closer than Previously Assumed". The Astronomical Journal. 153 (3). 125. arXiv:1610.06522. Bibcode:2017AJ....153..125S. doi:10.3847/1538-3881/aa5d0c. S2CID 119296636.
  13. Smith, Nathan; et al. (2019). "On the Gaia DR2 distances for Galactic Luminous Blue Variables". Monthly Notices of the Royal Astronomical Society. 488 (2): 1760–1778. arXiv:1805.03298. Bibcode:2019MNRAS.488.1760S. doi:10.1093/mnras/stz1712. S2CID 119267371.
  14. Bailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Demleitner, M.; Andrae, R. (2021). "Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3". The Astronomical Journal. 161 (3): 147. arXiv:2012.05220. Bibcode:2021AJ....161..147B. doi:10.3847/1538-3881/abd806. S2CID 228063812.
  15. "Hubble's Blue Bubble". NASA. 26 February 2016. Retrieved 1 March 2016.
  16. "Hubble Captures "Blue Bubble' Star—20 Times Bigger, a Million Times Brighter than the Sun's". Inquisitr. 29 February 2016. Retrieved 2 March 2016.
  17. 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 (1): 2–26. arXiv:1211.2505. Bibcode:2013MNRAS.431....2F. doi:10.1093/mnras/sts393. S2CID 119174103.
  18. ^ 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. S2CID 55776698.
  19. "Blue bubble in Carina". NASA. Retrieved 2 March 2016.
  20. "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 25 September 2024.
  21. Pojmanski, G. (2002). "The All Sky Automated Survey. Catalog of Variable Stars. I. 0 h – 6 h Quarter of the Southern Hemisphere". Acta Astronomica. 52: 397–427. arXiv:astro-ph/0210283. Bibcode:2002AcA....52..397P.
  22. "Hen 3-519". International Variable Star Index. American Association of Variable Star Observers. 4 January 2010. Retrieved 30 September 2016.
  23. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
Constellation of Carina
Stars
Bayer
Variable
HR
HD
Other
Exoplanets
Star
clusters
NGC
Other
Nebulae
NGC
Other
Galaxies
NGC
Other
Galaxy clusters
Astronomical events
Category
Categories: