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Sigma Librae

January 01, 1970

Sigma Librae (σ Librae, abbreviated Sigma Lib, σ Lib) is a binary star[11] in the constellation of Libra. The apparent visual magnitude is +3.29,[4] making it visible to the naked eye. Based upon parallax measurements, this system is at a distance of roughly 288 light-years (88 parsecs) from the Sun, with a 2% margin of error.[1] At that distance, the visual magnitude is diminished by 0.20 ± 0.17 from extinction caused by intervening gas and dust.[9]

σ Librae
Location of σ Librae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Libra
Right ascension 15h 04m 04.21608s[1]
Declination –25° 16′ 55.0606″[1]
Apparent magnitude (V) 3.20 - 3.46[2]
Characteristics
Spectral type M2.5III[3]
U−B color index +1.94[4]
B−V color index +1.70[4]
Variable type SRb[2]
Astrometry
Radial velocity (Rv)–4.2[5] km/s
Proper motion (μ) RA: –71.16[1] mas/yr
Dec.: −43.34[1] mas/yr
Parallax (π)11.31 ± 0.25 mas[1]
Distance288 ± 6 ly
(88 ± 2 pc)
Absolute magnitude (MV)–1.5[6]
Details
Mass2.2[7] M☉
Radius108[8] R☉
Luminosity1,820[7] L☉
Surface gravity (log g)0.9 ± 0.3[9] cgs
Temperature3,596[7] K
Metallicity [Fe/H]0.00[9] dex
Other designations
Brachium, 20 Librae, CD–24 11834, FK5 556, HD 133216, HIP 73714, HR 5603, SAO 183139.,[10] WDS 15041-2517[11]
Database references
SIMBADdata

The two components are designated Sigma Librae A (officially named Brachium /ˈbreɪkiəm/,[12] the traditional name for the system)[13] and B.

Nomenclature edit

σ Librae (Latinised to Sigma Librae) is the system's current Bayer designation (the star originally bore the designation Gamma Scorpii[14] and did not receive its current designation until the new designation was agreed upon by Commission 3 of the International Astronomical Union (IAU) on July 31, 1930.[15]) The designations of the two components as Sigma Librae A and B derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[16]

It bore the traditional Latin names Brachium (arm) and Cornu (horn), and the non-unique minor Arabic names Zuben el Genubi (southern claw) (shared with Alpha Librae); Zuben Hakrabi (shared with Gamma Librae and Eta Librae, also rendered as Zuban Alakrab), and Ankaa (shared with Alpha Phoenicis).[citation needed] In 2016, the IAU organized a Working Group on Star Names (WGSN)[17] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[18] It approved the name Brachium for the primary component Sigma Librae A on 5 September 2017. Ankaa had previously been approved as the name for Alpha Phoenicis on 29 July 2016. Both are now so included in the List of IAU-approved Star Names.[13]

In Chinese, 折威 (Shé Wēi), meaning Executions (asterism), refers to an asterism consisting of σ Librae, 50 Hydrae, 3 Librae, 4 Librae and 12 Librae.[19] Consequently, the Chinese name for σ Librae is 折威七 (Shé Wēi qī, English: the Seventh Star of Executions).[20]

Properties edit

The primary, Sigma Librae A, has a spectral class M2.5 III,[3] which places it in the red giant stage of its evolution. This is a semi-regular variable star with a single pulsation period of 20 days.[6] It shows small amplitude variations in magnitude of 0.10–0.15 on time scales as brief as 15–20 minutes, with cycles of repetition over intervals of 2.5–3.0 hours.[21] This form of variability indicates that the star is on the asymptotic giant branch and is generating energy through the nuclear fusion of hydrogen and helium along concentric shells surrounding an inert core of carbon and oxygen.[22]

The companion, Sigma Librae B, is of the 16th magnitude and over an arc minute away.[11]

References edit

  1. ^ a b c d e f van 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, S2CID 18759600.
  2. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. ^ a b Keenan, Philip C; McNeil, Raymond C (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373. S2CID 123149047.
  4. ^ a b c Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
  5. ^ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W.
  6. ^ a b Yeşilyaprak, C.; Aslan, Z. (December 2004), "Period-luminosity relation for M-type semiregular variables from Hipparcos parallaxes", Monthly Notices of the Royal Astronomical Society, 355 (2): 601–607, Bibcode:2004MNRAS.355..601Y, doi:10.1111/j.1365-2966.2004.08344.x.
  7. ^ a b c Tsuji, T (2008). "Cool luminous stars: The hybrid nature of their infrared spectra". Astronomy and Astrophysics. 489 (3): 1271–1289. arXiv:0807.4387. Bibcode:2008A&A...489.1271T. doi:10.1051/0004-6361:200809869. S2CID 19007399.
  8. ^ Cruzalèbes, P; Jorissen, A; Rabbia, Y; Sacuto, S; Chiavassa, A; Pasquato, E; Plez, B; Eriksson, K; Spang, A; Chesneau, O (2013). "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER". Monthly Notices of the Royal Astronomical Society. 434 (1): 437. arXiv:1306.3288. Bibcode:2013MNRAS.434..437C. doi:10.1093/mnras/stt1037. S2CID 49573767.
  9. ^ a b c Dehaes, S.; et al. (September 2011), "Structure of the outer layers of cool standard stars", Astronomy & Astrophysics, 533: A107, arXiv:0905.1240, Bibcode:2011A&A...533A.107D, doi:10.1051/0004-6361/200912442, S2CID 42053871
  10. ^ "sig Lib -- Semi-regular pulsating Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-14.
  11. ^ a b c . United States Naval Observatory. Archived from the original on 14 February 2011. Retrieved 2 January 2018.
  12. ^ "brachium". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  13. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
  14. ^ Burnham, Robert (1978), Burnham's celestial handbook: an observer's guide to the universe beyond the Solar System, Dover Books on Astronomy, vol. 2 (2nd ed.), Courier Dover Publications, p. 1108, ISBN 0486235688.
  15. ^ "Report of Commissions: Ephemerides", Transactions of the International Astronomical Union, 4: 20, 1932.
  16. ^ 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].
  17. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  18. ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  19. ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  20. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 28 日
  21. ^ Ruban, E. V.; Arkharov, A. A. (December 2010), "Microvariability and fast variability of stars. II. The semiregular red giants L2 Pup, 2 Cen, η Gem, and σ Lib", Astrophysics, 53 (4): 523–535, Bibcode:2010Ap.....53..523R, doi:10.1007/s10511-010-9144-7, S2CID 122054736.
  22. ^ Lebzelter, T.; Hron, J. (January 2008), "BRITE stars on the AGB", Communications in Asteroseismology, 152: 178–181, Bibcode:2008CoAst.152..178L, doi:10.1553/cia152s178

External links edit

  • Kaler, James B., "ZUBENHAKRABI (Sigma Librae = Gamma Scorpii)", Stars, University of Illinois, retrieved 2012-03-22

January 01, 1970
sigma, librae, librae, abbreviated, sigma, binary, star, constellation, libra, apparent, visual, magnitude, making, visible, naked, based, upon, parallax, measurements, this, system, distance, roughly, light, years, parsecs, from, with, margin, error, that, di. Sigma Librae s Librae abbreviated Sigma Lib s Lib is a binary star 11 in the constellation of Libra The apparent visual magnitude is 3 29 4 making it visible to the naked eye Based upon parallax measurements this system is at a distance of roughly 288 light years 88 parsecs from the Sun with a 2 margin of error 1 At that distance the visual magnitude is diminished by 0 20 0 17 from extinction caused by intervening gas and dust 9 s LibraeLocation of s Librae circled Observation dataEpoch J2000 0 Equinox J2000 0 ICRS Constellation Libra Right ascension 15h 04m 04 21608s 1 Declination 25 16 55 0606 1 Apparent magnitude V 3 20 3 46 2 Characteristics Spectral type M2 5III 3 U B color index 1 94 4 B V color index 1 70 4 Variable type SRb 2 AstrometryRadial velocity Rv 4 2 5 km sProper motion m RA 71 16 1 mas yr Dec 43 34 1 mas yrParallax p 11 31 0 25 mas 1 Distance288 6 ly 88 2 pc Absolute magnitude MV 1 5 6 DetailsMass2 2 7 M Radius108 8 R Luminosity1 820 7 L Surface gravity log g 0 9 0 3 9 cgsTemperature3 596 7 KMetallicity Fe H 0 00 9 dex Other designationsBrachium 20 Librae CD 24 11834 FK5 556 HD 133216 HIP 73714 HR 5603 SAO 183139 10 WDS 15041 2517 11 Database referencesSIMBADdata The two components are designated Sigma Librae A officially named Brachium ˈ b r eɪ k i e m 12 the traditional name for the system 13 and B Contents 1 Nomenclature 2 Properties 3 References 4 External linksNomenclature edits Librae Latinised to Sigma Librae is the system s current Bayer designation the star originally bore the designation Gamma Scorpii 14 and did not receive its current designation until the new designation was agreed upon by Commission 3 of the International Astronomical Union IAU on July 31 1930 15 The designations of the two components as Sigma Librae A and B derives from the convention used by the Washington Multiplicity Catalog WMC for multiple star systems and adopted by the International Astronomical Union IAU 16 It bore the traditional Latin names Brachium arm and Cornu horn and the non unique minor Arabic names Zuben el Genubi southern claw shared with Alpha Librae Zuben Hakrabi shared with Gamma Librae and Eta Librae also rendered as Zuban Alakrab and Ankaa shared with Alpha Phoenicis citation needed In 2016 the IAU organized a Working Group on Star Names WGSN 17 to catalog and standardize proper names for stars The WGSN decided to attribute proper names to individual stars rather than entire multiple systems 18 It approved the name Brachium for the primary component Sigma Librae A on 5 September 2017 Ankaa had previously been approved as the name for Alpha Phoenicis on 29 July 2016 Both are now so included in the List of IAU approved Star Names 13 In Chinese 折威 She Wei meaning Executions asterism refers to an asterism consisting of s Librae 50 Hydrae 3 Librae 4 Librae and 12 Librae 19 Consequently the Chinese name for s Librae is 折威七 She Wei qi English the Seventh Star of Executions 20 Properties editThe primary Sigma Librae A has a spectral class M2 5 III 3 which places it in the red giant stage of its evolution This is a semi regular variable star with a single pulsation period of 20 days 6 It shows small amplitude variations in magnitude of 0 10 0 15 on time scales as brief as 15 20 minutes with cycles of repetition over intervals of 2 5 3 0 hours 21 This form of variability indicates that the star is on the asymptotic giant branch and is generating energy through the nuclear fusion of hydrogen and helium along concentric shells surrounding an inert core of carbon and oxygen 22 The companion Sigma Librae B is of the 16th magnitude and over an arc minute away 11 References edit a b c d e f van Leeuwen F November 2007 Validation of the new Hipparcos reduction Astronomy and Astrophysics 474 2 653 664 arXiv 0708 1752 Bibcode 2007A amp A 474 653V doi 10 1051 0004 6361 20078357 S2CID 18759600 a b Samus N N Durlevich O V et al 2009 VizieR Online Data Catalog General Catalogue of Variable Stars Samus 2007 2013 VizieR On line Data Catalog B GCVS Originally Published in 2009yCat 102025S 1 Bibcode 2009yCat 102025S a b Keenan Philip C McNeil Raymond C 1989 The Perkins catalog of revised MK types for the cooler stars Astrophysical Journal Supplement Series 71 245 Bibcode 1989ApJS 71 245K doi 10 1086 191373 S2CID 123149047 a b c Nicolet B 1978 Photoelectric photometric Catalogue of homogeneous measurements in the UBV System Astronomy and Astrophysics Supplement Series 34 1 49 Bibcode 1978A amp AS 34 1N Wielen R et al 1999 Sixth Catalogue of Fundamental Stars FK6 Part I Basic fundamental stars with direct solutions Veroff Astron Rechen Inst Heidelb 35 35 Astronomisches Rechen Institut Heidelberg 1 Bibcode 1999VeARI 35 1W a b Yesilyaprak C Aslan Z December 2004 Period luminosity relation for M type semiregular variables from Hipparcos parallaxes Monthly Notices of the Royal Astronomical Society 355 2 601 607 Bibcode 2004MNRAS 355 601Y doi 10 1111 j 1365 2966 2004 08344 x a b c Tsuji T 2008 Cool luminous stars The hybrid nature of their infrared spectra Astronomy and Astrophysics 489 3 1271 1289 arXiv 0807 4387 Bibcode 2008A amp A 489 1271T doi 10 1051 0004 6361 200809869 S2CID 19007399 Cruzalebes P Jorissen A Rabbia Y Sacuto S Chiavassa A Pasquato E Plez B Eriksson K Spang A Chesneau O 2013 Fundamental parameters of 16 late type stars derived from their angular diameter measured with VLTI AMBER Monthly Notices of the Royal Astronomical Society 434 1 437 arXiv 1306 3288 Bibcode 2013MNRAS 434 437C doi 10 1093 mnras stt1037 S2CID 49573767 a b c Dehaes S et al September 2011 Structure of the outer layers of cool standard stars Astronomy amp Astrophysics 533 A107 arXiv 0905 1240 Bibcode 2011A amp A 533A 107D doi 10 1051 0004 6361 200912442 S2CID 42053871 sig Lib Semi regular pulsating Star SIMBAD Centre de Donnees astronomiques de Strasbourg retrieved 2012 01 14 a b c Washington Double Star Catalog United States Naval Observatory Archived from the original on 14 February 2011 Retrieved 2 January 2018 brachium Oxford English Dictionary Online ed Oxford University Press Subscription or participating institution membership required a b Naming Stars IAU org Retrieved 16 December 2017 Burnham Robert 1978 Burnham s celestial handbook an observer s guide to the universe beyond the Solar System Dover Books on Astronomy vol 2 2nd ed Courier Dover Publications p 1108 ISBN 0486235688 Report of Commissions Ephemerides Transactions of the International Astronomical Union 4 20 1932 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 IAU Working Group on Star Names WGSN Retrieved 22 May 2016 WG Triennial Report 2015 2018 Star Names PDF p 5 Retrieved 2018 07 14 in Chinese 中國星座神話 written by 陳久金 Published by 台灣書房出版有限公司 2005 ISBN 978 986 7332 25 7 in Chinese AEEA Activities of Exhibition and Education in Astronomy 天文教育資訊網 2006 年 6 月 28 日 Ruban E V Arkharov A A December 2010 Microvariability and fast variability of stars II The semiregular red giants L2 Pup 2 Cen h Gem and s Lib Astrophysics 53 4 523 535 Bibcode 2010Ap 53 523R doi 10 1007 s10511 010 9144 7 S2CID 122054736 Lebzelter T Hron J January 2008 BRITE stars on the AGB Communications in Asteroseismology 152 178 181 Bibcode 2008CoAst 152 178L doi 10 1553 cia152s178External links editKaler James B ZUBENHAKRABI Sigma Librae Gamma Scorpii Stars University of Illinois retrieved 2012 03 22 Retrieved from https en wikipedia org w index php title Sigma Librae amp oldid 1210070919, wikipedia, wiki, book, books, library,

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