View source for HD 37974

{{Short description|Star in the constellation Dorado}}
{{Starbox begin
| name=HD 37974
}}
{{Starbox image
| image = [[File:Supersized Disk.tif|280px]]
| caption = Artist concept of the stars, Sun and planets not drawn to scale
}}
{{Starbox observe
| epoch=J2000
| ra={{RA|05|36|25.843}}<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|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}}</ref>
| dec={{DEC|–69|22|55.90}}<ref name=tycho2/>
| appmag_v=10.95<ref name=ducati>{{cite journal|bibcode= 2002yCat.2237....0D |title= VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system |journal= CDS/ADC Collection of Electronic Catalogues |volume= 2237 |last1= Ducati |first1= J. R. |year= 2002 }}</ref>
| constell=[[Dorado]]
}}
{{Starbox character
| class=B0.5Ia<sup>+</sup><ref name=kastner>{{Cite journal | last1 = Kastner | first1 = J. H. | last2 = Buchanan | first2 = C. L. | last3 = Sargent | first3 = B. | last4 = Forrest | first4 = W. J. | title = SpitzerSpectroscopy of Dusty Disks around B\e] Hypergiants in the Large Magellanic Cloud | doi = 10.1086/500804 | journal = The Astrophysical Journal | volume = 638 | pages = L29–L32 | year = 2006 | issue = 1 |bibcode = 2006ApJ...638L..29K | doi-access = free }}</ref>
| b-v=+0.15<ref name=ducati/>
| u-b=&minus;0.88<ref name=ducati/>
| variable=[[Luminous blue variable|LBV]]?<ref name=vangenderen>{{cite journal|bibcode=2002A&A...386..926V|title=Light variations of massive stars (alpha Cyg variables). XVIII. The B[e] supergiants S 18 in the SMC and R 66 = HDE 268835 and R 126 = HD 37974 in the LMC|journal=Astronomy and Astrophysics|volume=386|issue=3|pages=926|last1=Van Genderen|first1=A. M.|last2=Sterken|first2=C.|year=2002|doi=10.1051/0004-6361:20020360|doi-access=free}}</ref><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>
}}
{{Starbox astrometry
| radial_v=258<ref>{{cite journal|bibcode=1960MNRAS.121..337F|title=The brightest stars in the Magellanic Clouds|journal=Monthly Notices of the Royal Astronomical Society|volume=121|issue=4|pages=337|last1=Feast|first1=M. W.|last2=Thackeray|first2=A. D.|last3=Wesselink|first3=A. J.|year=1960|doi=10.1093/mnras/121.4.337|doi-access=free}}</ref>
| prop_mo_ra=-1.8<ref name=tycho2/>
| prop_mo_dec=-15.1<ref name=tycho2/>
| parallax=0.22
| p_error=0.42
| parallax_footnote=<ref name=dr1>{{cite journal|bibcode=2016yCat.1337....0G|title=VizieR Online Data Catalog: Gaia DR1 (Gaia Collaboration, 2016)|journal=VizieR On-line Data Catalog: I/337. Originally Published in: Astron. Astrophys.|volume=1337|author1=Gaia Collaboration|year=2016}}</ref>
| absmag_v=−8.4<ref name=vangenderen/>
}}
{{Starbox detail
| source=<ref name=kastner/>
| mass=70
| radius={{Solar radius calculator|type=LT|1400000|22500}}{{Efn|Radius calculated with temperature and luminosity|name=Temperature and luminosity}}
| luminosity=1,400,000
| temperature=22,500
| metal=
| rotation=
| age=
}}
{{Starbox catalog
| names= [[RMC (star catalog)|RMC]]&nbsp;126, R&nbsp;126, [[Henry Draper Catalogue|HD]]&nbsp;37974, [[Guide Star Catalog|GSC]]&nbsp;09167-00518, AL&nbsp;361, [[GV (star catalog)|GV]]&nbsp;408, MSX&nbsp;LMC&nbsp;890, [[Durchmusterung|CPD]]-69°420, [[Mount Wilson Observatory|MWC]]&nbsp;123, [[LHA (star catalog)|LHA]]&nbsp;120-S 127, [[LI-LMC]]&nbsp;1413, LMC&nbsp;V3566; [[2MASS]] J05362586-6922558<ref name=gcvs/>
}}
{{Starbox reference
| Simbad = RMC+126
}}
{{Starbox end}}
'''HD 37974''' (or '''R 126''') a [[variable star|variable]] [[B(e) star|B[e]]] [[hypergiant]] in the [[Large Magellanic Cloud]]. It is surrounded by an unexpected dust disk.
==Properties==
R126, formally RMC (Radcliffe observatory Magellanic Cloud) 126, is a massive luminous star with several unusual properties. It exhibits the B[e] phenomenon where [[Forbidden mechanism|forbidden]] [[emission line]]s appear in the spectrum due to extended [[circumstellar envelope|circumstellar material]]. Its spectrum also shows normal (permitted) emission lines formed in denser material closer to the star, indicative of a power [[stellar wind]].<ref name=levato>{{cite journal|bibcode=2014A&A...568A..28L|title=New objects with the B[e] phenomenon in the Large Magellanic Cloud|journal=Astronomy & Astrophysics|volume=568|pages=A28|last1=Levato|first1=H.|last2=Miroshnichenko|first2=A. S.|last3=Saffe|first3=C.|year=2014|doi=10.1051/0004-6361/201423846|doi-access=free|hdl=11336/4973|hdl-access=free}}</ref> The spectra include [[silicate]] and [[polycyclic aromatic hydrocarbon]] (PAH) features that suggest a dusty disc.<ref name=kastner/>
The star itself is a hot supergiant thought to be seventy times more massive than the Sun and over a million times more luminous. It has evolved away from the main sequence (being an O-class star, when it was in MS{{citation needed|date=October 2018}}) and is so luminous and large that it is losing material through its stellar wind over a billion times faster than the Sun. It would lose more material than the Sun contains in about 25,000 years.<ref name=zsargo>{{cite journal|bibcode=2008A&A...478..543Z|arxiv=0712.0870|title=Axi-symmetric models of B[e] supergiants. I. The effective temperature and mass-loss dependence of the hydrogen and helium ionization structure|journal=Astronomy and Astrophysics|volume=478|issue=2|pages=543|last1=Zsargó|first1=J.|last2=Hillier|first2=D. J.|last3=Georgiev|first3=L. N.|year=2008|doi=10.1051/0004-6361:20078293|s2cid=55234776}}</ref>
It is expected to evolve into [[Wolf–Rayet star]] in several hundred thousand years.{{citation needed|date=October 2018}}
==Dusty disc==
The dust cloud around R126 is surprising because stars as massive as these were thought to be inhospitable to planet formation due to powerful stellar winds making it difficult for dust particles to condense. The nearby hypergiant [[HD 268835]] shows similar features and is also likely to have a dusty disc, so R126 is not unique.<ref name=kastner/>
The disc extends outwards for 60 times the size of Pluto's orbit around the Sun, and probably contains as much material as the entire [[Kuiper belt]]. It is unclear whether such a disc represents the first or last stages of the planet-forming process.<ref>[http://www.nasa.gov/vision/universe/starsgalaxies/spitzer-20060208.html NASA's Spitzer Uncovers Hints of Mega Solar Systems] {{Webarchive|url=https://web.archive.org/web/20160304220027/http://www.nasa.gov/vision/universe/starsgalaxies/spitzer-20060208.html |date=2016-03-04 }}, Nasa.gov, accessed 11 Feb 2006</ref>
==Variability==
[[File:HD37974LightCurve.png|thumb|left|A [[light curve]] for HD 37974, adapted from Pedersen ''et al.'' (2019)<ref name="Pedersen"/>]]
The brightness of R126 varies in an unpredictable way by around 0.6 magnitude over timescales of tens to hundreds of days. The faster variations are characteristic of [[α Cygni variable]]s, irregular pulsating supergiants. The slower variations are accompanied by changes in the colour of the star, with it being redder when it is visually brighter, typical of the [[S Doradus]] phases of [[luminous blue variable]]s.<ref name=vangenderen/>
{{clear left}}
==See also ==
* [[List of most massive stars]]
==References==
{{reflist|refs=
<ref name="Pedersen">{{cite journal |last1=Pedersen |first1=May G. |last2=Chowdhury |first2=Sowgata |last3=Johnston |first3=Cole |last4=Bowman |first4=Dominic M. |last5=Aerts |first5=Conny |last6=Handler |first6=Gerald |last7=De Cat |first7=Peter |last8=Neiner |first8=Coralie |last9=David-Uraz |first9=Alexandre |last10=Buzasi |first10=Derek |last11=Tkachenko |first11=Andrew |last12=Simón-Díaz |first12=Sergio |last13=Moravveji |first13=Ehsan |last14=Sikora |first14=James |last15=Mirouh |first15=Giovanni M. |last16=Lovekin |first16=Catherine C. |last17=Cantiello |first17=Matteo |last18=Daszyńska-Daszkiewicz |first18=Jadwiga |last19=Pigulski |first19=Andrzej |last20=Vanderspek |first20=Roland K. |last21=Ricker |first21=George R. |title=Diverse Variability of O and B Stars Revealed from 2-minute Cadence Light Curves in Sectors 1 and 2 of the TESS Mission: Selection of an Asteroseismic Sample |journal=The Astrophysical Journal Letters |date=February 10, 2019 |volume=872 |issue=1 |page=L9 |doi=10.3847/2041-8213/ab01e1 |arxiv=1901.07576 |bibcode=2019ApJ...872L...9P |s2cid=118963697 |doi-access=free }}</ref>
}}
<references group="lower-alpha"/>
{{Stars of Dorado}}
{{DEFAULTSORT:HD 37974}}
[[Category:Stars in the Large Magellanic Cloud]]
[[Category:Dorado]]
[[Category:B-type hypergiants]]
[[Category:Large Magellanic Cloud]]
[[Category:Extragalactic stars|R126]]
[[Category:Henry Draper Catalogue objects|037974]]
[[Category:Alpha Cygni variables]]
[[Category:B(e) stars]]
[[Category:2MASS objects|J05362586-6922558]]
[[Category:Durchmusterung objects|CPD-69 420]]