| 词条 | WR 20a |
| 释义 |
| name=WR 20a }}{{Starbox image | image={{Location mark |image=NASA Unveils Celestial Fireworks as Official Hubble 25th Anniversary Image.jpg|alt=|float=center|width=300 |label=|position=right |mark=Cercle jaune 100%.svg|mark_width=10|mark_link=WR 20a |x=651|y=352 }} |caption=WR 20a (circled) near Westerlund 2 |credit=NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team }}{{Starbox observe | epoch=J2000 | ra= {{RA|10|23|58.002}}[1] | dec= {{DEC|−57|45|48.99}}[1] | appmag_v=13.28[3] | constell=Carina }}{{Starbox character | type=Hot slash star[2] | class=O3If*/WN6 + O3If*/WN6[3] | b-v=+1.63[3] | u-b=+0.29[3] | variable=β Lyr + WR[4] }}{{Starbox astrometry | radial_v= | prop_mo_ra= | prop_mo_dec= | parallax= | p_error= | dist_pc= 7900 ± 600 | dist_ly= 20000[3] | absmag_v=−6.49 + −6.49[3] }}{{Starbox orbit | reference = [11] | primary = | name = | period = | period_unitless = 3.675 days | axis = | axis_unitless = {{solar radius|26}} | eccentricity = 0 | inclination = | node = | periastron = | periarg = | periarg_primary = | k1 = 353.1 | k2 = 362.6 }}{{Starbox detail | source=[3] | mass=82.7 ± 5.5 | radius= 19.3 ± 0.5 | luminosity=1,150,000 ± 150,000 | temperature=43000 ± 2000 | gravity=3.8 | metal= | rotation= | age= | mass2=81.9 ± 5.5 | radius2=19.3 ± 0.5 | luminosity2=1,150,000 ± 150,000 | temperature2=43000 ± 2000 | gravity2=3.8 | metal2= | rotation2= | age2= | orbital period 3.7 days }}{{Starbox catalog | names= V712 Carinae, GEN#+4.38020004, THA 35-II-36, Westerlund 2 MSP 240, 2MASS J10235800-5745489, UBV M 40466, Westerlund 2 4 }}{{Starbox reference |Simbad = WR+20a }}{{Starbox end}}WR20a is a binary star associated with the young, massive cluster Westerlund 2. It was discovered in 2004 to be one of the most massive binary systems known, for which the masses of the components have been accurately measured.[5] Each star in the system has about eighty times the mass of the Sun.[5][6] It is not clear why this system is located away from the center of the cluster. It is possible that the system was formed in the core, but that it was ejected by dynamical interactions. Every 3.6 days the two stars in this system revolve around each other. Although the stars are in very tight orbit, both stars in the system are detached.[7] It is expected that within a million years the two will expand and come into contact. A large nitrogen abundance has been measured on the surface of the stars,[8] about six times the abundance of nitrogen measured in the sun. This nitrogen is probably produced in deeper layers of the star and pushed towards the surface by rotational mixing. A collision between the two winds of the systems has been detected in the visible as well as in X-rays.[8][9] The X-ray emitting region is quite extended since it does not suffer from any eclipse. References1. ^1 {{cite journal|bibcode=2003yCat.2246....0C|title=VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)|journal=VizieR On-line Data Catalog: II/246. Originally published in: 2003yCat.2246....0C|volume=2246|author1=Cutri|first1=R. M.|last2=Skrutskie|first2=M. F.|last3=Van Dyk|first3=S.|last4=Beichman|first4=C. A.|last5=Carpenter|first5=J. M.|last6=Chester|first6=T.|last7=Cambresy|first7=L.|last8=Evans|first8=T.|last9=Fowler|first9=J.|last10=Gizis|first10=J.|last11=Howard|first11=E.|last12=Huchra|first12=J.|last13=Jarrett|first13=T.|last14=Kopan|first14=E. L.|last15=Kirkpatrick|first15=J. D.|last16=Light|first16=R. M.|last17=Marsh|first17=K. A.|last18=McCallon|first18=H.|last19=Schneider|first19=S.|last20=Stiening|first20=R.|last21=Sykes|first21=M.|last22=Weinberg|first22=M.|last23=Wheaton|first23=W. A.|last24=Wheelock|first24=S.|last25=Zacarias|first25=N.|year=2003}} {{Stars of Carina}}2. ^{{cite journal|bibcode=2011MNRAS.416.1311C|arxiv=1105.4757|title=Spectral classification of O2-3.5 If*/WN5-7 stars|journal=Monthly Notices of the Royal Astronomical Society|volume=416|issue=2|pages=1311|author1=Crowther|first1=Paul A.|last2=Walborn|first2=Nolan R.|year=2011|doi=10.1111/j.1365-2966.2011.19129.x}} 3. ^{{cite journal|bibcode=2013MNRAS.433..712R|arxiv=1305.0851|title=An O2 If*/WN6 star caught in the act in a compact H II region in the starburst cluster NGC 3603|journal=Monthly Notices of the Royal Astronomical Society|volume=433|pages=712|author1=Roman-Lopes|first1=A.|year=2013|doi=10.1093/mnras/stt762}} 4. ^{{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|author1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}} 5. ^1 2 {{cite journal |author=Rauw |display-authors=etal |title=WR20a: a massive cornerstone binary system comprising two extreme early-type stars |journal=Astronomy & Astrophysics |volume=420 |issue=2 |date=3 June 2004 |doi=10.1051/0004-6361:20040150 |arxiv=astro-ph/0404551 |bibcode=2004A&A...420L...9R |pages=L9–L13}} 6. ^{{cite journal|bibcode=2004ApJ...611L..33B|arxiv=astro-ph/0405338|title=WR 20a is an Eclipsing Binary: Accurate Determination of Parameters for an Extremely Massive Wolf-Rayet System|journal=The Astrophysical Journal|volume=611|pages=L33|author1=Bonanos|first1=A. Z.|last2=Stanek|first2=K. Z.|last3=Udalski|first3=A.|last4=Wyrzykowski|first4=L.|last5=Żebruń|first5=K.|last6=Kubiak|first6=M.|last7=Szymański|first7=M. K.|last8=Szewczyk|first8=O.|last9=Pietrzyński|first9=G.|last10=Soszyński|first10=I.|year=2004|doi=10.1086/423671}} 7. ^{{cite journal |author=Rauw |display-authors=etal |title=Early-type stars in the core of the young open cluster Westerlund 2 |journal=Astronomy & Astrophysics |volume=463 |issue=3 |pages=981–991 |date=1 March 2007 |doi=10.1051/0004-6361:20066495 |bibcode=2007A&A...463..981R|arxiv = astro-ph/0612622 }} 8. ^1 2 3 4 5 6 7 {{cite journal |author=Rauw |display-authors=etal |title=The spectrum of the very massive binary system WR 20a (WN6ha + WN6ha): Fundamental parameters and wind interactions |journal=Astronomy & Astrophysics |volume=432 |issue=3 |pages=985–998 |date=4 March 2005 |doi=10.1051/0004-6361:20042136 |bibcode=2005A&A...432..985R|url=https://pure.uva.nl/ws/files/2178609/46516_211088y.pdf }} 9. ^{{cite journal |author=Naze |display-authors=etal |title=Chandra monitoring of the very massive binary WR20a and the young massive cluster Westerlund 2 |journal=Astronomy & Astrophysics |volume=483 |issue=1 |pages=171–182 |date=1 May 2008 |doi=10.1051/0004-6361:20078851 |bibcode=2008A&A...483..171N |arxiv = 0801.0647 }} 6 : Wolf–Rayet stars|Beta Lyrae variables|Carina (constellation)|2MASS objects|Objects with variable star designations|Spectroscopic binaries |
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