| 词条 | WR 21a |
| 释义 |
| name=WR 21a }}{{Starbox image | image={{Location mark |image=Westerlund 2.jpg|alt=|float=center|width=280 |label=|position=right |mark=Green circle.png|mark_width=10|mark_link=WR 21a |x=77|y=589 }} |caption=Location of WR 21a (circled) near RCW 49 |credit=ESO }}{{Starbox observe | epoch=J2000 | ra= {{RA|10|25|56.50}}[1] | dec= {{DEC|−57|48|43.5}}[1] | appmag_v=12.661[2] | constell=Carina }}{{Starbox character | class=O3/WN5ha + O3Vz((f*))[3] | b-v=+1.507[2] | u-b= | variable= }}{{Starbox astrometry | radial_v= | prop_mo_ra=−2.5[2] | prop_mo_dec=+2.1[2] | parallax= | p_error= | dist_ly= | dist_pc= ~8,000[3] | absmag_v=−7.20[3] }}{{Starbox orbit | reference = [3] | primary = WR | name = O | period = | period_unitless = 31.672 ± 0.011 days | axis = | axis_unitless = {{solar radius|230}}[4] | eccentricity = 0.6949 ± 0.0047 | inclination = 58.8 ± 2.5 | node = | periastron = | periarg = | periarg_primary = | k1 = 156.9 ± 2.0 | k2 = 278.6 ± 5.3 }}{{Starbox detail | source= | component1=WR | mass=103.6 ± 10.2[3] | radius=12.0[4] | luminosity=1,800,000[3] | temperature=45,000[5] | gravity= | metal= | rotation= | age= | component2=O | mass2=58.3 ± 3.7[3] | radius2=13.84[4] | luminosity2=630,000[3] | temperature2=50,680[5] | gravity2= | metal2= | rotation2= | age_myr2=1.5[3] }}{{Starbox catalog | names= WR 21a, 2MASS J10255650-5748435 }}{{Starbox reference |Simbad = WR+21a }}{{Starbox end}} WR 21a is a binary star in the constellation Carina. It includes one of the most massive known stars and is one of the most massive binaries. WR 21a lies near the Westerlund 2 open cluster and may be an ejected member.[6] The distance of WR 21a is not definitely known. There have been estimates from 2.85 kpc to around 8 kpc, with consequent uncertainties in the system luminosity. The larger distance is preferred because of consistency with the derived orbital parameters,[5] but it is still uncertain whether the star is nearer or further than Westerlund 2.[7] Every 31 days and 16 hours days the two stars in this system revolve around each other. The inclination of the orbit means that we do not see eclipses and the visual brightness of the system is quite stable.[3] The colliding winds of the two stars produce extremely high temperatures and luminous x-ray emission.[4] The system is also bright at radio wavelengths.[5]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. ^1 2 3 {{cite journal|bibcode=2013AJ....145...44Z|title=The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)|journal=The Astronomical Journal|volume=145|issue=2|pages=44|author1=Zacharias|first1=N.|last2=Finch|first2=C. T.|last3=Girard|first3=T. M.|last4=Henden|first4=A.|last5=Bartlett|first5=J. L.|last6=Monet|first6=D. G.|last7=Zacharias|first7=M. I.|year=2013|doi=10.1088/0004-6256/145/2/44|arxiv = 1212.6182 }} 3. ^1 2 3 4 5 6 7 8 9 {{cite journal|bibcode=2016MNRAS.455.1275T|arxiv=1510.03609|title=The mass of the very massive binary WR21a|journal=Monthly Notices of the Royal Astronomical Society|volume=455|issue=2|pages=1275–1281|author1=Tramper|first1=F.|last2=Sana|first2=H.|last3=Fitzsimons|first3=N. E.|last4=De Koter|first4=A.|last5=Kaper|first5=L.|last6=Mahy|first6=L.|last7=Moffat|first7=A.|year=2016|doi=10.1093/mnras/stv2373}} 4. ^1 2 3 {{cite journal|bibcode=2016A&A...590A.113G|title=The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR21a|volume=1604|pages=A113|arxiv=1604.01536|author1=Gosset|first1=Eric|last2=Naze|first2=Yael|year=2016|doi=10.1051/0004-6361/201527051|journal=Astronomy & Astrophysics}} 5. ^1 2 3 {{cite journal|bibcode=2005A&A...440..743B|arxiv=astro-ph/0506363|title=Multiwavelength studies of WR 21a and its surroundings|journal=Astronomy and Astrophysics|volume=440|issue=2|pages=743–750|author1=Benaglia|first1=P.|last2=Romero|first2=G. E.|last3=Koribalski|first3=B.|last4=Pollock|first4=A. M. T.|year=2005|doi=10.1051/0004-6361:20042617}} 6. ^{{cite journal|bibcode=2015MNRAS.446.3797H|arxiv=1411.0879|title=Reddening, distance, and stellar content of the young open cluster Westerlund 2|journal=Monthly Notices of the Royal Astronomical Society|volume=446|issue=4|pages=3797–3819|author1=Hur|first1=Hyeonoh|last2=Park|first2=Byeong-Gon|last3=Sung|first3=Hwankyung|last4=Bessell|first4=Michael S.|last5=Lim|first5=Beomdu|last6=Chun|first6=Moo-Young|last7=Sohn|first7=Sangmo Tony|year=2015|doi=10.1093/mnras/stu2329}} 7. ^{{cite journal|bibcode=2013A&A...555A..50C|arxiv=1305.4309|title=The distance to the young open cluster Westerlund 2|journal=Astronomy & Astrophysics|volume=555|pages=A50|author1=Carraro|first1=G.|last2=Turner|first2=D.|last3=Majaess|first3=D.|last4=Baume|first4=G.|year=2013|doi=10.1051/0004-6361/201321421}} 5 : Wolf–Rayet stars|Spectroscopic binaries|Carina (constellation)|2MASS objects|O-type main-sequence stars |
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