R136c
{{Short description|Star in the constellation Dorado}}
{{Starbox begin
| name = R136c
}}
{{Starbox image
| image = 300px
| caption = The bright star to the left of the cluster core is R136c.
}}
{{Starbox observe
| epoch = J2000.0
| equinox = J2000.0
| constell = Dorado
}}
{{Starbox character
| type = Wolf–Rayet star
| class = WN5h{{cite journal|bibcode=2016MNRAS.458..624C|arxiv=1603.04994|title=The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of He II λ1640 in young star clusters|journal=Monthly Notices of the Royal Astronomical Society|volume=458|issue=1|pages=624–659|last1=Crowther|first1=Paul A.|last2=Caballero-Nieves|first2=S. M.|last3=Bostroem|first3=K. A.|last4=Maíz Apellániz|first4=J.|last5=Schneider|first5=F. R. N.|last6=Walborn|first6=N. R.|last7=Angus|first7=C. R.|last8=Brott|first8=I.|last9=Bonanos|first9=A.|last10=De Koter|first10=A.|last11=De Mink|first11=S. E.|author11-link= Selma de Mink |last12=Evans|first12=C. J.|last13=Gräfener|first13=G.|last14=Herrero|first14=A.|last15=Howarth|first15=I. D.|last16=Langer|first16=N.|last17=Lennon|first17=D. J.|last18=Puls|first18=J.|last19=Sana|first19=H.|last20=Vink|first20=J. S.|year=2016|doi=10.1093/mnras/stw273|doi-access=free }}
}}
{{Starbox astrometry
| radial_v =
| prop_mo_ra =
| prop_mo_dec =
| parallax =
| p_error =
| parallax_footnote =
| dist_ly = 163,000
| space_v_u =
| space_v_v =
| space_v_w =
}}
{{Starbox orbit
| period_unitless = 17.2051 days
| eccentricity = {{val|0.31|0.08}}
| k1 = {{val|51|9}}
}}
{{Starbox detail
| mass = 142
| luminosity = 3,800,000
| radius = 40.7
| temperature = 42,170
| rotational_velocity = <200
| age_myr = 1.8
}}
{{Starbox catalog
| names= BAT99 112, RMC 136c, VFTS 1025
}}
{{Starbox reference
| Simbad = RMC+136c
| ARICNS =
}}
{{Starbox end}}
R136c is a likely binary star located in R136, a tight knot of stars at the centre of NGC 2070, an open cluster weighing 450,000 solar masses and containing 10,000 stars.{{cite journal | last=Bosch | first=Guillermo |author2=Terlevich, Elena|author2-link=Elena Terlevich |author3=Terlevich, Roberto | title=Gemini/GMOS Search for Massive Binaries in the Ionizing Cluster of 30 Dor | journal=Astronomical Journal | volume=137 |issue=2 | pages=3437–3441 | date=2009 | bibcode=2009AJ....137.3437B | doi=10.1088/0004-6256/137/2/3437|arxiv = 0811.4748 | s2cid=17976455 }} At {{Solar mass|142|link=y}} and 3.8 million {{Solar luminosity|link=y}}, it is one of the most massive stars known and one of the most luminous, along with being one of the hottest, at over {{val|40,000|ul=K|fmt=commas}}. It was first resolved and named by Feitzinger in 1980, along with R136a and R136b.{{cite journal|bibcode=1980A&A....84...50F|title=The central object R 136 in the gas nebula 30 Doradus - Structure, color, mass and excitation parameter|journal=Astronomy and Astrophysics|volume=84|issue=1–2|pages=50|last1=Feitzinger|first1=J. V.|last2=Schlosser|first2=W.|last3=Schmidt-Kaler|first3=T.|last4=Winkler|first4=C.|year=1980}}
Description
R136c is a Wolf–Rayet star of the spectral type WN5h and with a temperature of {{val|42,170|u=K|fmt=commas}}, making it one of hottest stars known. It is the one of the most massive stars known, with a mass of {{Solar mass|142|link=y}}, and it is one of the most luminous stars known, with a luminosity of 3.8 million {{Solar luminosity|link=y}}. The extreme luminosity is produced by the CNO fusion process in its highly compressed hot core. Typical of all Wolf–Rayet stars, R136c has been losing mass by means of a strong stellar wind with speeds over {{val|2,000|u=km/s|fmt=commas}} and mass loss rates in excess of {{val|e=-5}} solar masses per year.{{Cite journal |last1=Crowther |first1=P. A. |last2=Schnurr |first2=O. |last3=Hirschi |first3=R. |last4=Yusof |first4=N. |last5=Parker |first5=R. J. |last6=Goodwin |first6=S. P. |last7=Kassim |first7=H. A. |year=2010 |title=The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 M⊙ stellar mass limit |journal=Monthly Notices of the Royal Astronomical Society |volume=408 |issue=2 |pages=731 |arxiv=1007.3284 |bibcode=2010MNRAS.408..731C |doi=10.1111/j.1365-2966.2010.17167.x |doi-access=free |s2cid=53001712 }}
It is strongly suspected to be a binary, due to the detection of hard x-ray emission typical of colliding wind binaries, but the companion is thought to make only a small contribution to the total luminosity.{{Cite journal | doi = 10.1051/0004-6361/201322696| title = The Wolf-Rayet stars in the Large Magellanic Cloud| journal = Astronomy & Astrophysics| volume = 565| pages = A27| year = 2014| last1 = Hainich | first1 = R.| last2 = Rühling | first2 = U.| last3 = Todt | first3 = H.| last4 = Oskinova | first4 = L. M.| last5 = Liermann | first5 = A.| last6 = Gräfener | first6 = G.| last7 = Foellmi | first7 = C.| last8 = Schnurr | first8 = O.| last9 = Hamann | first9 = W. -R. | arxiv = 1401.5474| bibcode = 2014A&A...565A..27H| s2cid = 55123954}} Absorption lines in the spectrum, tentatively assigned to the companion, indicate that it is considerably more massive than the Wolf-Rayet component. An orbit has been derived, but with low confidence and even the period is uncertain, between 5 and 47 days.{{cite journal |bibcode=2023A&A...679A..36S |title=Constraints on the multiplicity of the most massive stars known: R136 a1, a2, a3, and C |last1=Shenar |first1=T. |last2=Sana |first2=H. |last3=Crowther |first3=P. A. |last4=Bostroem |first4=K. A. |last5=Mahy |first5=L. |last6=Najarro |first6=F. |last7=Oskinova |first7=L. |last8=Sander |first8=A. A. C. |journal=Astronomy and Astrophysics |date=2023 |volume=679 |pages=A36 |doi=10.1051/0004-6361/202346930 |arxiv=2309.13113 }}
Evolution
R136c is so energetic that it has already lost a substantial fraction of its initial mass, even though it is only a few million years old. It is still effectively on the main sequence, fusing hydrogen at its core via the CNO cycle, but it has convected and mixed fusion products to the surface and these create a powerful stellar wind and emission spectrum normally only seen in highly evolved stars.
Its fate depends on the amount of mass it loses before its core collapses, but is likely to result in a supernova. The most recent models for single star evolution at near-solar metallicities suggest that the most massive stars explode as highly stripped type Ic supernovae, although different outcomes are possible for binaries. Some of these supernovae are expected to produce a type of gamma-ray burst and the expected remnant is a black hole.{{Cite journal | doi = 10.1051/0004-6361/201321906| title = Fundamental properties of core-collapse supernova and GRB progenitors: Predicting the look of massive stars before death| journal = Astronomy & Astrophysics| volume = 558| pages = A131| year = 2013| last1 = Groh | first1 = J. H. | last2 = Meynet | first2 = G. | last3 = Georgy | first3 = C. | last4 = Ekström | first4 = S. | bibcode = 2013A&A...558A.131G|arxiv = 1308.4681 | s2cid = 84177572}}