Beta Scorpii
  | |
| Observation data EpochJ2000.0EquinoxJ2000.0 | |
|---|---|
| Constellation | Scorpius |
| HR 5984 | |
| Right ascension | 16h05m26.23198s[1] |
| Declination | –19° 48′ 19.6300″[1] |
| Apparent magnitude(V) | 2.62[2] |
| HR 5985 | |
| Right ascension | 16h05m26.57128s[1] |
| Declination | –19° 48′ 06.8556″[1] |
| Apparent magnitude(V) | 4.92[2] |
| Characteristics | |
| HR 5984 | |
| Spectral type | B1V[3](B0.5IV-V + B1.5V)[4] |
| U−Bcolor index | –0.08[5] |
| B−Vcolor index | –0.08[5] |
| HR 5985 | |
| Spectral type | B2V[3] |
| U−Bcolor index | –0.70[5] |
| B−Vcolor index | –0.02[5] |
| Astrometry | |
| HR 5984 | |
| Radial velocity(Rv) | –1.0[6]km/s |
| Proper motion(μ) | RA:–5.20[1]mas/yr Dec.:–24.04[1]mas/yr |
| Parallax(π) | 8.07 ± 0.78mas[1] |
| Distance | 400 ± 40ly (120 ± 10pc) |
| Absolute magnitude(MV) | –3.92 / –2.60[7] |
| HR 5985 | |
| Radial velocity(Rv) | –3.6[6]km/s |
| Proper motion(μ) | RA:–5.07[1]mas/yr Dec.:–25.87[1]mas/yr |
| Parallax(π) | 8.19 ± 1.17mas[1] |
| Distance | approx. 400ly (approx. 120pc) |
| Absolute magnitude(MV) | –1.83 (Ea: +0.24)[7] |
| Details[7] | |
| β Sco Aa | |
| Mass | 15.0M☉ |
| Radius | 6.3R☉ |
| Luminosity | 31,600L☉ |
| Temperature | 28,000K |
| β Sco Ab | |
| Mass | 10.4M☉ |
| Radius | 4.0R☉ |
| Luminosity | 7,900L☉ |
| Temperature | 26,400K |
| β Sco C | |
| Mass | 8.2M☉ |
| Radius | 2.9R☉ |
| Luminosity | 3,200L☉ |
| Surface gravity(logg) | 3.8cgs |
| Temperature | 24,000K |
| Rotational velocity(vsini) | 55 km/s |
| β Sco Ea | |
| Mass | 3.5M☉ |
| Radius | 2.4R☉ |
| Luminosity | 126L☉ |
| Surface gravity(logg) | 4.2cgs |
| Temperature | 13,000K |
| Rotational velocity(vsini) | 5 km/s |
| Age | 6.3Myr |
| Other designations | |
| β1Sco:BD–19 4307,HD144217,HIP78820,HR5984 | |
| β2Sco:BD–19 4308, HD 144218, HIP 78821, HR 5985 | |
| Database references | |
| SIMBAD | β Scorpii |
| β1Scorpii | |
| β2Scorpii | |
Beta Scorpii(β Scorpii,abbreviatedBeta Sco,β Sco) is amultiple star systemin the southernzodiacconstellationofScorpius.It bore the traditional proper name ofAcrab/ˈækræb/,[8]though theInternational Astronomical Unionnow regards that name as applying only to the β Scorpii Aa component.
Components
[edit]Observed through a small telescope, Beta Scorpii appears as abinary starwith a separation between the two components of 13.5arcsecondsand a combinedapparent magnitudeof 2.50. This pair, designated β¹ Scorpii and β² Scorpii, form the top branches of a hierarchy of six orbiting components.
| Aa | |||||||||||||||
| Period = 6.82d a = 1.42 mas | |||||||||||||||
| Ab | |||||||||||||||
| Period = 610y a = 0.30″ | |||||||||||||||
| B | |||||||||||||||
| 13.5″ separation | |||||||||||||||
| C | |||||||||||||||
| Period = 39y a = 0.1328″ | |||||||||||||||
| Ea | |||||||||||||||
| Period = 10.7d | |||||||||||||||
| Eb | |||||||||||||||
Hierarchy of orbits in the β Scorpii system
β¹ Scorpii, the brighter of the pair, consists of two sub-components, designated β Scorpii A and β Scorpii B, orbiting at an angular separation of 0.3 arcseconds with an orbital period of 610 years. β Scorpii A is itself aspectroscopic binary,with the two components designated β Scorpii Aa (also named Acrab[9]) and β Scorpii Ab. They are separated by 1.42milliarcsecondsand have an orbital period of 6.82 days.[10]
β² Scorpii also has two sub-components, designated β Scorpii C and β Scorpii E, orbiting at an angular separation of 0.1328 arcseconds with an orbital period of 39 years. β Scorpii E in turn is a spectroscopic binary with components designated β Scorpii Ea and β Scorpii Eb and having an orbital period of 10.7 days.
Component β Scorpii D is the unrelated seventh magnitude star HD 144273, 520 "away.[11]Some authors have also referred to component Ab as D.[12]
A companion to component B, β Scorpii G, has been proposed to account for missing mass in the system, but no further evidence of its existence has been found.[7]β Scorpii F refers to a theorised companion to component E.[12]
Nomenclature
[edit]β Scorpii(LatinisedtoBeta Scorpii) is the star'sBayer designation;β¹andβ² Scorpii,those of its two components. The designations of the sub-components -β Scorpii A,Aa,Ab,B,C,E,EaandEb- derive from the convention used by the Washington Multiplicity Catalog (WMC) formultiple star systems,and adopted by theInternational Astronomical Union(IAU).[13]
Beta Scorpii bore the traditional namesAcrab,AkraborElacrab,all deriving from theArabicname (Arabic:العقرب)al-'Aqrab'the Scorpion' for the whole constellation, as well asGraffias/ˈɡræfiəs/,[14]Italian for "the claws", a name it shared withXi Scorpii.[15][16]
In 2016, theInternational Astronomical Unionorganized aWorking Group on Star Names(WGSN)[17]to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entiremultiple systems.[18]It approved the nameAcrabfor the componentβ Scorpii Aaon 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[9]
InChinese,Phòng túc(Fáng Xiù), meaningRoom,refers to an asterism consisting of both of β1Scorpii and β2Scorpii,π Scorpii,ρ Scorpiiandδ Scorpii,.[19]Consequently, theChinese namefor both of β1Scorpii and β2Scorpii isPhòng túc tứ(Fáng Xiù sì), "the Fourth Star of Room".[20]
Namesake
[edit]USS Graffias (AF-29)was once aUnited Statesnavy ship named after the star.
Properties
[edit]
The β Scorpii system is a kinematic member of the Upper Scorpius subgroup of theScorpius–Centaurus association,a group of thousands of young stars with mean age 11 million years at distance 470 light years (145 parsecs). Analysis of β1Scorpii as a single star derived an evolutionary age between 9 and 12 million years,[21]but analysis of the β Scorpii system as a whole suggest an age closer to 6 million years.[7]
The two components of β Scorpii A are the most massive members of the system, 15M☉and 10M☉respectively. The combined spectral type is B1 V. The individual spectral types cannot be clearly measured, but are estimated to be B0.5 and B1.5. Component Aa is evolving slightly away from thezero age main sequenceand itsluminosity classis estimated to be intermediate betweensubgiant(IV) andmain sequence(V). Component Ab has a main sequence luminosity class, a temperature of 26,400 K, and a luminosity of 7,900L☉.
Component B is over 20 times fainter than the combined component A stars and a clear spectral type has not been measured. Its mass is estimated to be approximately 8M☉.[12]
Component C has a stellar classification of B2 V and a mass of 8M☉.It has aneffective surface temperatureof 24,000 K, a radius of 2.9R☉and abolometric luminosityof 3,200L☉.
Component E is determined to have a temperature of 13,000 K, radius of 2.4R☉,and luminosity of 126L☉.It ischemically peculiar,with high abundances ofmanganeseandstrontium.It is possibly amercury-manganese(HgMn) star, but abundances of other metals are unexpectedly low.[7]
Beta Scorpii is 1.01 degree from theeclipticand can be occulted by theMoonand, very rarely, byplanets.On December 9, 1906, it was occulted byVenus.[22]The lastoccultationby a planet took place on 13 May 1971, byJupiter.[23]
In culture
[edit]Beta Scorpii appears on theflag of Brazil,symbolising the state ofMaranhão.[24]
References
[edit]- ^abcdefghijvan Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction",Astronomy and Astrophysics,474(2): 653–664,arXiv:0708.1752,Bibcode:2007A&A...474..653V,doi:10.1051/0004-6361:20078357,S2CID18759600
- ^abHoffleit, D.; Warren Jr., W. H. (1991)."Entry for HR 2491".Bright Star Catalogue, 5th Revised Ed. (Preliminary Version).CDS.IDV/50.
- ^abAbt, H. A. (1981). "Visual multiples. VII - MK classifications".Astrophysical Journal Supplement Series.45:437.Bibcode:1981ApJS...45..437A.doi:10.1086/190719.
- ^Holmgren, D.; Hadrava, P.; Harmanec, P.; Koubsky, P.; Kubat, J. (1997). "Search for forced oscillations in binaries. II. β Scorpii A. New physical parameters and a search for line profile variability".Astronomy and Astrophysics.322:565.Bibcode:1997A&A...322..565H.
- ^abcdJohnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars",Communications of the Lunar and Planetary Laboratory,4(99): 99,Bibcode:1966CoLPL...4...99J
- ^abEvans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.).Determination of Radial Velocities and their Applications.IAU Symposium no. 30. Vol. 30. University of Toronto: International Astronomical Union. p. 57.Bibcode:1967IAUS...30...57E.
- ^abcdefCatanzaro, G. (2010)."First spectroscopic analysis of β Scorpii C and β Scorpii E. Discovery of a new HgMnstar in the multiple system β Scorpii ".Astronomy and Astrophysics.509:A21.Bibcode:2010A&A...509A..21C.doi:10.1051/0004-6361/200913332.
- ^Rumrill, H. B. (June 1936)."Star Name Pronunciation".Publications of the Astronomical Society of the Pacific.48(283). San Francisco, California: 139.Bibcode:1936PASP...48..139R.doi:10.1086/124681.S2CID120743052.
- ^ab"Naming Stars".IAU.org.Retrieved18 June2018.
- ^Mason, Brian D.; Hartkopf, William I.; Tokovinin, Andrei (September 2010), "Binary Star Orbits. IV. Orbits of 18 Southern Interferometric Pairs",The Astronomical Journal,140(3): 735–743,Bibcode:2010AJ....140..735M,doi:10.1088/0004-6256/140/3/735
- ^Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001)."The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog".The Astronomical Journal.122(6): 3466.Bibcode:2001AJ....122.3466M.doi:10.1086/323920.
- ^abcVan Flandern, T. C.; Espenschied, P. (1975)."Lunar occultations of beta Scorpii in 1975 and 1976".Astrophysical Journal.200:61.Bibcode:1975ApJ...200...61V.doi:10.1086/153760.
- ^Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets".arXiv:1012.0707[astro-ph.SR].
- ^Davis, George A. (1944)."The pronunciations, derivations, and meanings of a selected list of star names".Popular Astronomy.52:8–30.Bibcode:1944PA.....52....8D.
- ^Aitken, R. G. (1924)."The Zodiacal Constellation Scorpio".Publications of the Astronomical Society of the Pacific.36(211): 124–130.Bibcode:1924PASP...36..124A.doi:10.1086/123392.JSTOR40692425.
- ^Allen, Richard Hinckley(1963) [1899].Star Names: Their Lore and Meaning(Revised ed.). New York:Dover Publications.p.367.ISBN0-486-21079-0.
- ^IAU Working Group on Star Names (WGSN),International Astronomical Union,retrieved22 May2016.
- ^"WG Triennial Report (2015-2018) - Star Names"(PDF).p. 5.Retrieved2018-07-14.
- ^(in Chinese)Trung quốc tinh tọa thần thoại,written by trần cửu kim. Published by đài loan thư phòng xuất bản hữu hạn công tư, 2005,ISBN978-986-7332-25-7.
- ^(in Chinese)Hương cảng thái không quán - nghiên cứu tư nguyên - lượng tinh trung anh đối chiếu biểuArchived2008-10-25 at theWayback Machine,Hong Kong Space Museum. Accessed on line November 23, 2010.
- ^Mark J. Pecaut; Eric E. Mamajek & Eric J. Bubar (February 2012). "A Revised Age for Upper Scorpius and the Star Formation History among the F-type Members of the Scorpius–Centaurus OB Association".Astrophysical Journal.746(2): 154.arXiv:1112.1695.Bibcode:2012ApJ...746..154P.doi:10.1088/0004-637X/746/2/154.S2CID118461108.
- ^Können, G. P.; Van Maanen, J. (April 1981), "Planetary occultations of bright stars.",Journal of the British Astronomical Association,91:148–157,Bibcode:1981JBAA...91..148K
- ^Bartholdi, P.; Owen, F. (1972). "The Occultation of Beta Scorpii by Jupiter and Io. II. Io".Astronomical Journal.77:60–65.Bibcode:1972AJ.....77...60B.doi:10.1086/111245.
- ^"Astronomy of the Brazilian Flag".FOTW Flags Of The World website.Retrieved2017-05-16.
