| 词条 | Theta2 Orionis |
| 释义 |
|name= θ2 Orionis }}{{Starbox image | image= | caption=The three components of θ2 Orionis, plus nearby stars | credit=Ian Nartowicz (derived from ESA/Hubble image) }}{{Starbox observe 3s | epoch = J2000 | constell = Orion | component1 = A | ra1 = {{RA|05|35|22.90115}}[1] | dec1 = {{DEC|−05|24|57.8207}}[1] |appmag_v1 = 5.02[2] | component2 = B | ra2 = {{RA|05|35|26.4018}}[3] | dec2 = {{DEC|−05|25|00.720}}[3] | appmag_v2 = 6.380[4] | component3 = C | ra3 = {{RA|05|35|31.436}}[5] | dec3 = {{DEC|−05|25|16.40}}[3] | appmag_v3 = 8.18[6] }}{{Starbox character | class = O9.5IVp[7] + B0.7V[8] + B5V[9] | b-v = | u-b = | variable = }}{{Starbox astrometry | radial_v = 35.6[10] | prop_mo_ra = 2.29[1] | prop_mo_dec = 0.96[1] | parallax = 2.11 | p_error = 0.41 | parallax_footnote = [1] | absmag_v = −4.3[11] + −2.60[4] + −0.6[12] }}{{Starbox detail | component1 = A | mass = 39[13] | radius = | luminosity = 107,000[14] | temperature = 34,900[14] | gravity = | metal_fe = | rotational_velocity = 133[8] | age_myr = }}{{Starbox detail|no_heading=y | component1 = B | mass = 14.8[4] | radius = 4.3[4] | luminosity = 12,300[4] | temperature = 29,300[4] | gravity = 4.30[4] | metal_fe = | rotational_velocity = 33[8] | age_myr = <2[4] }}{{Starbox detail|no_heading=y | component1 = C | mass = 4.86[14] | radius = | luminosity = 616[14] | temperature = 13,800[14] | gravity = | metal_fe = | rotational_velocity = 78[15] | age_myr = <1[15] }}{{Starbox catalog | names = θ2 Ori, STF 4016, WDS J05354-0525, ADS 4188 | component1 = θ2 Ori A | names1 = 43 Ori, HR 1897, BD−05°1319, HD 37041, SAO 132321, HIP 26235, CCDM 05353-0524E | component2 = θ2 Ori B | names2 = BD−05°1320, HD 37042, SAO 132322, CCDM 05353-0524F | component3 = θ2 Ori C | names3 = V361 Ori, BD−05°1326, HD 37062, SAO 132329, S 490A, CCDM 05353-0524G }}{{Starbox reference | Simbad=tet02+Ori+A |name=θ2 Ori A | Simbad2=tet02+Ori+B |name2=θ2 Ori B | Simbad3=tet02+Ori+C |name3=θ2 Ori C }}{{Starbox end}} Theta2 Orionis (θ2 Ori) is a multiple star system in the constellation Orion. It is a few arc minutes from its more famous neighbour the Trapezium Cluster, also known as θ1 Orionis. Componentsθ2 Orionis consists of three stars in a line, each about an arc-minute from the next. In addition to the well-known three stars, the Washington Double Star Catalog confusingly lists a component D which is actually θ1 Orionis C.[16] There is one other star brighter than 10th magnitude in the region. V1073 Orionis is a B9.5 Orion variable that forms an equilateral triangle with θ2 Ori B and C. Bizarrely, θ2 Orionis C has a second entry in the Washington Double Star Catalog under the name S490. The companion is 10th magnitude and actually lies between θ2 Ori B and V1073 Ori.[16] θ1 Orionis, the well known Trapezium cluster, is only 2 arc minutes away from θ2 Orionis A. Despite the names, θ2 Orionis A is marginally brighter than the brightest star in the Trapezium. The Catalog of Components of Double and Multiple Stars includes the stars of θ1 and θ2 Ori within the same system of 13 components. There are dozens of much fainter stars in the same field, many of them pre-main-sequence stars still forming from the Orion Molecular Cloud Complex. PropertiesThe primary component A appears as a 5th magnitude O class subgiant over 100,000 times as luminous as the sun. The spectral type suggests it is evolving away from the main sequence, although it is thought to be less than 2 million years old. The spectral peculiarities may be related to close companions or could be caused by the extreme youth of the star. The 6th magnitude component B is an early B main sequence star nearly 30,000 K and over 10,000 times the luminosity of the sun. Component C is another B class main sequence star, but cooler and less than a thousand times the luminosity of the sun. θ2 Orionis A systemθ2 Orionis A is itself a triple star system. Its spectral lines were seen to change position periodically, indicating orbital motion. The first orbit was derived in 1924, indicating a period of 21 days. and a rather eccentric orbit.[17] Speckle interferometry has resolved a companion about 0.3" away, around 147 AU. High resolution spectroscopy shows that there is an even closer companion, only about 0.47 AU from the primary, for a total of three stars. Both companions are thought to be early A or late B with masses of {{solar mass|7-9}}. This helps to explain the high mass and visual luminosity for an O9.5 star at this distance. The three stars together have nearly the same mass as the O5.5 θ1 Orionis C and visually are even brighter.[18]θ2 Orionis A also shows unexplained rapidly variable x-ray emission. The x-rays cannot be explained standard mechanisms such as colliding winds or coronal emissions from an unseen companion.[13] References1. ^1 2 3 4 {{cite journal|bibcode=2007A&A...474..653V|title=Validation of the new Hipparcos reduction|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653|author1=Van Leeuwen|first1=F.|year=2007|doi=10.1051/0004-6361:20078357|arxiv = 0708.1752 }} {{Stars of Orion}}2. ^{{cite journal|bibcode=2015AJ....149...26A|title=The Multiplicity of Massive Stars: A High Angular Resolution Survey with the Guidance Sensor|journal=The Astronomical Journal|volume=149|pages=26|author1=Aldoretta|first1=E. J.|last2=Caballero-Nieves|first2=S. M.|last3=Gies|first3=D. R.|last4=Nelan|first4=E. P.|last5=Wallace|first5=D. J.|last6=Hartkopf|first6=W. I.|last7=Henry|first7=T. J.|last8=Jao|first8=W.-C.|last9=Maíz Apellániz|first9=J.|last10=Mason|first10=B. D.|last11=Moffat|first11=A. F. J.|last12=Norris|first12=R. P.|last13=Richardson|first13=N. 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C.|year=1978|doi=10.1086/156554}} 12. ^{{cite journal|bibcode=1979ApJ...230..485A|title=The occurrence of abnormal stars in open clusters|journal=Astrophysical Journal|volume=230|pages=485|author1=Abt|first1=H. A.|year=1979|doi=10.1086/157104}} 13. ^1 {{cite journal|bibcode=2011ApJ...734...14M|arxiv=1009.1896|title=Detailed X-Ray Line Properties of θ2 Ori a in Quiescence|journal=The Astrophysical Journal|volume=734|pages=14|author1=Mitschang|first1=Arik W.|last2=Schulz|first2=Norbert S.|last3=Huenemoerder|first3=David P.|last4=Nichols|first4=Joy S.|last5=Testa|first5=Paola|year=2011|doi=10.1088/0004-637X/734/1/14}} 14. ^1 2 3 4 {{cite journal|bibcode= 1997AJ....113.1733H|title= On the Stellar Population and Star-Forming History of the Orion Nebula Cluster|journal= Astronomical Journal |volume= 113|pages= 1733|author1= Hillenbrand|first1= Lynne A.|year= 1997|doi= 10.1086/118389}} 15. ^1 {{cite journal|doi=10.1046/j.1365-8711.2002.05540.x|title=Non-emission-line young stars of intermediate mass|journal=Monthly Notices of the Royal Astronomical Society|volume=334|issue=2|pages=419|year=2002|last1=Manoj|first1=P.|last2=Maheswar|first2=G.|last3=Bhatt|first3=H. C.|arxiv = astro-ph/0204491 |bibcode = 2002MNRAS.334..419M }} 16. ^1 {{cite journal|bibcode=2001AJ....122.3466M|title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog|journal=The Astronomical Journal|volume=122|issue=6|pages=3466|author1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|last4=Douglass|first4=Geoffrey G.|last5=Worley|first5=Charles E.|year=2001|doi=10.1086/323920}} 17. ^{{cite journal|bibcode=1924ApJ....60..159S|title=The orbit of the spectroscopic binary 43 theta-2 Orionis|journal=Astrophysical Journal|volume=60|pages=159|author1=Struve|first1=O.|year=1924|doi=10.1086/142845}} 18. ^{{cite journal|bibcode=2006ApJ...653..636S|arxiv=astro-ph/0608420|title=X-Ray Variability in the Young Massive Triple θ2 Orionis A|journal=The Astrophysical Journal|volume=653|pages=636|author1=Schulz|first1=Norbert S.|last2=Testa|first2=Paola|last3=Huenemoerder|first3=David P.|last4=Ishibashi|first4=Kazunori|last5=Canizares|first5=Claude R.|year=2006|doi=10.1086/508625}} 12 : Orion (constellation)|B-type main-sequence stars|Bayer objects|O-type subgiants|Orion variables|Triple star systems|Hipparcos objects|HR objects|Henry Draper Catalogue objects|Durchmusterung objects|Flamsteed objects|Objects with variable star designations |
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