Alpha Librae: Difference between revisions

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imported>21.Andromedae
That is Alpha2
 
imported>21.Andromedae
blue straggler?
 
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{{short description|Binary star in the constellation Libra}}
{{short description|Quadruple star in the constellation Libra}}
{{Starbox begin
{{Starbox begin
  | name = α Librae
  | name = α Librae
Line 16: Line 16:
  | epoch      = [[J2000.0]]
  | epoch      = [[J2000.0]]
  | constell    = [[Libra (constellation)|Libra]]
  | constell    = [[Libra (constellation)|Libra]]
  | component1  = α<sup>1</sup> Lib
  | component1  = {{nobr|α<sup>1</sup> Lib}} {{nobr|(α Lib B)}}
  | ra1        = {{RA|14|50|41.18097}}<ref name=aaa474_2_653/>
  | ra1        = {{RA|14|50|41.18097}}<ref name=hipparcos/>
  | dec1        = {{DEC|-15|59|50.0482}}<ref name=aaa474_2_653/>
  | dec1        = {{DEC|-15|59|50.0482}}<ref name=hipparcos/>
  | appmag_v1  = +5.153<ref name=sps1966/>
  | appmag_v1  = +5.153<ref name=sps1966/>
  | component2  = α<sup>2</sup> Lib
  | component2  = {{nobr|α<sup>2</sup> Lib}} {{nobr|(α Lib A)}}
  | ra2        = {{RA|14|50|52.71309}}<ref name=aaa474_2_653/>
  | ra2        = {{RA|14|50|52.71309}}<ref name=hipparcos/>
  | dec2        = {{DEC|-16|02|30.3955}}<ref name=aaa474_2_653/>
  | dec2        = {{DEC|-16|02|30.3955}}<ref name=hipparcos/>
  | appmag_v2  = +2.741<ref name=sps1966/>
  | appmag_v2  = +2.741<ref name=sps1966/>
}}
}}
{{Starbox character
{{Starbox character
  | component = α<sup>1</sup> Lib
  | component   = α<sup>1</sup> Lib
  | class      = F3 V<ref name=mk/>
  | class      = F3 V<ref name=mk/> + M0{{endash}}1 V<ref name=Caballero2010/>
  | b-v        = +0.39<ref name=EgUBV/>
  | b-v        = +0.39<ref name=EgUBV/>
  | u-b        = −0.02<ref name=EgUBV/>
  | u-b        = −0.02<ref name=EgUBV/>
Line 33: Line 33:
}}
}}
{{Starbox character|no_heading=y
{{Starbox character|no_heading=y
  | component =  α<sup>2</sup> Lib
  | component   = α<sup>2</sup> Lib
  | class      = kA2hA5mA4 IV-V<ref name=apj132_1_161/>
  | type        = [[Main sequence]]<ref name=Zorec2012/><ref name=Takeda2018/> or [[blue straggler]] (α<sup>2</sup>&nbsp;A)<ref name=Waisberg2023/>
  | b-v        = +0.15<ref name=EgUBV>{{cite journal|author1=Mermilliod, J.-C.|title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)|journal=Catalogue of Eggen's UBV Data|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1|date=1986|bibcode= 1986EgUBV........0M }}</ref>
  | class      = kA2hA5mA4 IV-V<ref name=Gray2006/>
  | b-v        = +0.15<ref name=EgUBV/>
  | u-b        = +0.10<ref name=EgUBV/>
  | u-b        = +0.10<ref name=EgUBV/>
  | variable    =  
  | variable    =  
Line 41: Line 42:
{{Starbox astrometry
{{Starbox astrometry
  | component1  = α<sup>1</sup> Lib
  | component1  = α<sup>1</sup> Lib
  | radial_v    = −23.47<ref name=orbit/>
  | radial_v    = {{Val|−23.8|0.3}}<ref name=Fuhrmann2014/>
  | prop_mo_ra  = −136.27<ref name=aaa474_2_653/>
  | prop_mo_ra  = −136.27<ref name=hipparcos/>
  | prop_mo_dec = −59.04<ref name=aaa474_2_653/>
  | prop_mo_dec = −59.04<ref name=hipparcos/>
  | parallax    = 43.52
  | parallax    = 43.52
  | p_error    = 0.43
  | p_error    = 0.43
  | parallax_footnote = <ref name=aaa474_2_653/>
  | parallax_footnote = <ref name=hipparcos/>
  | absmag_v    = +3.35<ref name=aaa501_3_941/>
  | absmag_v    = +3.35<ref name=Holmerg2009/>
  | component2 = α<sup>2</sup> Lib
  | component2 = α<sup>2</sup> Lib
  | radial_v2 =  
  | radial_v2   =  
  | prop_mo_ra2 = −105.68<ref name=aaa474_2_653/>
  | prop_mo_ra2 = −105.68<ref name=hipparcos/>
  | prop_mo_dec2 = −68.40<ref name=aaa474_2_653/>
  | prop_mo_dec2 = −68.40<ref name=hipparcos/>
  | parallax2 = 43.03
  | parallax2   = 43.03
  | p_error2 = 0.19
  | p_error2   = 0.19
  | parallax_footnote2 = <ref name=aaa474_2_653/>
  | parallax_footnote2 = <ref name=hipparcos/>
  | absmag_v2 =
  | absmag_v2   = +0.88<ref name=ap1999/>
}}
{{Starbox orbit
| reference    = <ref name=soar2023/>
| primary      = α<sup>1</sup> Lib A
| name        = α<sup>1</sup> Lib B
| period      = {{val|16.229|0.043}}
| periastron  = {{val|2021.95|0.12}}
| eccentricity = {{val|0.244|0.008}}
| axis        = {{val|0.346|0.006}}
| node        = {{val|122.7|1.4}}
| periarg      = {{val|184.1|3.3}}
| inclination  = {{val|54.4|1.5}}
| k1          = {{val|3.83|0.12}}
}}
}}
{{Starbox orbit
{{Starbox orbit
| reference = <ref name=orbit/>
| reference   = <ref name=Fuhrmann2014/>
| primary = α<sup>2</sup> Lib A
| primary     = α<sup>2</sup> Lib A
| name = α<sup>2</sup> Lib B
| name         = α<sup>2</sup> Lib B
| period_unitless = 70.34 days
| period_unitless = {{val|70.34|0.07}} days
| eccentricity = 0.41
| axis_unitless= 0.52<ref name=Waisberg2023/> au
| axis_unitless = 0.51 au
| eccentricity = {{val|0.41|0.02}}
| k2 = 43.1
| inclination  = {{val|71|3}}<ref name=Waisberg2023/>
| node        = {{val|333|17}}<ref name=Waisberg2023/>
| periastron  = JD {{val|2455294.3|0.5}}
| periarg      = {{val|48|7}}
| k2           = {{val|43.1|0.5}}
}}
}}
{{Starbox detail
{{Starbox detail
  | component1  = α<sup>1</sup> Lib A
  | component1  = α<sup>1</sup> Lib A
  | mass        = {{val|1.36|0.02}}<ref name="luck"/>
  | mass        = 1.95<ref name=Waisberg2023/>
  | radius      = {{solar radius calculator|type=logLT|0.55|6707|decimals=2}}0<ref name="luck"/>{{efn|name=radius}}
  | radius      = 2.21<ref name=Waisberg2023/>
| luminosity  = 3.55<ref name="luck"/>
  | temperature = 8,200<ref name=Waisberg2023/>
  | temperature = {{val|6707|56|fmt=commas}}<ref name="luck"/>
  | gravity    = 3.91<ref name=Gray2006/>
| metal_fe    = {{val|-0.03}}<ref name="luck"/>
  | age_myr     = 700<ref name=Waisberg2023/>
  | gravity    = 4.27<ref name="luck"/>
  | rotational_velocity = 5.95<ref name="luck"/>
| age_gyr     = {{val|1.01|0.24}}<ref name="luck"/>
  | component2  = α<sup>1</sup> Lib B
  | component2  = α<sup>1</sup> Lib B
  | mass2 = 0.5–0.6<ref name=aaa514_A98/>
  | mass2       = 1.79<ref name=Waisberg2023/>
| radius2    = 1.92<ref name=Waisberg2023/>
| temperature2= 7,930<ref name=Waisberg2023/>
| age_myr2    = 700<ref name=Waisberg2023/>
}}
}}
{{Starbox detail|no_heading=y
{{Starbox detail|no_heading=y
  | component1 = α<sup>2</sup> Lib A
  | component1 = α<sup>2</sup> Lib A
  | mass = 1.95<ref name=waisberg/>
  | mass       = {{val|1.36|0.02}}<ref name=Luck2017/>
  | radius = 2.21<ref name=waisberg/>
  | radius     = 1.50<ref name=tic/>
  | temperature = 8,200<ref name=waisberg/>
| luminosity  = 3.83<ref name=Luck2017/>
  | gravity = 3.91<ref name=apj132_1_161/>
  | temperature = {{val|6707|56|fmt=commas}}<ref name=Luck2017/>
  | component2 = α<sup>2</sup> Lib B
  | metal_fe    = −0.03<ref name=Luck2017/>
  | mass2 = 1.79<ref name=waisberg/>
  | gravity    = 4.23<ref name=Luck2017/>
  | radius2 = 1.92<ref name=waisberg/>
  | rotational_velocity = 5.95<ref name=Luck2017/>
  | temperature2 = 7,930<ref name=waisberg/>
  | age_gyr    = {{val|1.01|0.24}}<ref name=Luck2017/>
  | component2  = α<sup>2</sup> Lib B
| mass2      = 0.5–0.6<ref name=Caballero2010/>
}}
}}
{{Starbox catalog
{{Starbox catalog
  | names = Zubenelgenubi, Kiffa Australis, Lanx Australis, α Lib.
  | names = {{odlist |name=Zubenelgenubi |name2=Kiffa Australis |name3=Lanx Australis |B=α Lib |WDS=J14509-1603 }}
  | component1 = α<sup>1</sup> Lib
  | component1 = α Lib B
| names1 = 8 Librae, [[Bonner Durchmusterung|BD]]−15&nbsp;3965, [[FK5]]&nbsp;1387, [[Henry Draper Catalogue|HD]]&nbsp;130819, [[Hipparcos catalogue|HIP]]&nbsp;72603, [[Bright Star Catalogue|HR]]&nbsp;5530, [[Smithsonian Astrophysical Observatory Star Catalogue|SAO]]&nbsp;158836.<ref name=SIMBAD1/>
| names1 = {{odlist |B=α<sup>1</sup> Lib |F=8 Librae |BD=−15°3965 |FK5=1387 |HD=130819 |HIP=72603 |HR=5530 |SAO=158836 }}<ref name=SIMBAD1/>
  | component2 = α<sup>2</sup> Lib
  | component2 = α Lib A
| names2 = 9 Librae, [[Bonner Durchmusterung|BD]]−15&nbsp;3966, [[FK5]]&nbsp;548, [[Henry Draper Catalogue|HD]]&nbsp;130841, [[Hipparcos catalogue|HIP]]&nbsp;72622, [[Bright Star Catalogue|HR]]&nbsp;5531, [[Smithsonian Astrophysical Observatory Star Catalogue|SAO]]&nbsp;158840.<ref name=SIMBAD2/>
| names2 = {{odlist |B=α<sup>2</sup> Lib |F=9 Librae |BD=−15°3966 |FK5=548 |HD=130841 |HIP=72622 |HR=5531 |SAO=158840 }}<ref name=SIMBAD2/>
}}
}}
{{Starbox reference
{{Starbox reference
|Simbad=alf+Lib|sn=α Lib
|Simbad=alf01+Lib|sn=α<sup>1</sup> Lib
|Simbad2=alf01+Lib|sn2=α<sup>1</sup> Lib
|Simbad3=alf02+Lib|sn3=α<sup>2</sup> Lib
|Simbad3=alf02+Lib|sn3=α<sup>2</sup> Lib
}}
}}
{{Starbox end}}
{{Starbox end}}
'''Alpha Librae''' ('''α Librae''', abbreviated '''Alpha Lib''', '''α Lib''') is a [[double star]] and, despite its '[[alpha]]' designation, it is the second-brightest star system (or star) in the [[constellation]] of [[Libra (constellation)|Libra]]. The two components are designated '''α<sup>1</sup> Librae''' and '''α<sup>2</sup> Librae'''. The system bore the traditional name of '''Zubenelgenubi''' {{IPAc-en|z|uː|ˌ|b|ɛ|n|ɛ|l|dʒ|ɪ|ˈ|n|uː|b|i}},<ref name=Kunitzsch>{{cite book
'''Alpha Librae''' ('''α Librae''', abbreviated '''Alpha Lib''', '''α Lib''') is a quadruple star system and, despite its '[[alpha]]' designation, it is the second-brightest star in the [[constellation]] of [[Libra (constellation)|Libra]]. The two components are designated '''α<sup>1</sup> Librae''' and '''α<sup>2</sup> Librae'''. The system bore the traditional name of '''Zubenelgenubi''' {{IPAc-en|z|uː|ˌ|b|ɛ|n|ɛ|l|dʒ|ɪ|ˈ|n|uː|b|i}},<ref name=Kunitzsch/> though the [[International Astronomical Union]] now regards that name as only applying to α<sup>2</sup> Librae.<ref name=IAU-CSN/>
  |last1=Kunitzsch |first1=Paul
  |last2=Smart |first2=Tim
  |date = 2006  |edition = 2nd rev.
  |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
  |publisher = Sky Pub |location = Cambridge, Massachusetts
  |isbn = 978-1-931559-44-7
}}</ref> though the [[International Astronomical Union]] now regards that name as only applying to α<sup>2</sup> Librae.<ref name="IAU-CSN">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref>


Alpha<sup>2</sup> Librae is 0.33 degrees north of the [[ecliptic]] so it can be [[occultation|occulted]] by the [[Moon]] and (very rarely) by [[planet]]s. It was occulted by [[Venus]] on October 25, 1947;<ref name=Koennen1981/> the next occultation by a planet will be by [[Mercury (planet)|Mercury]] on 10 November 2052.<ref name=occultation>Peuschel, Marco (2003). [http://www.marco-peuschel.de/planetensterne.html "Astronomische Ereignisse der besonderen Art"] {{webarchive|url=https://web.archive.org/web/20050316042622/http://www.marco-peuschel.de/planetensterne.html |date=2005-03-16 }}. Retrieved July 10, 2005.</ref>  Both components are eclipsed ([[occultation|occulted]]) by the sun from about 7–9 November.<ref>[http://in-the-sky.org/skymap.php?year=2019&month=November&day=9 In the Sky] Earth astronomy reference utility showing the ecliptic and relevant date as at J2000 - present</ref> Thus the star can be viewed the whole night, crossing the sky, in early May.
Alpha<sup>2</sup> Librae is 0.33 degrees north of the [[ecliptic]] so it can be [[occultation|occulted]] by the [[Moon]] and (very rarely) by [[planet]]s. It was occulted by [[Venus]] on October 25, 1947;<ref name=Koennen1981/> the next occultation by a planet will be by [[Mercury (planet)|Mercury]] on 10 November 2052.<ref name=occultation>Peuschel, Marco (2003). [http://www.marco-peuschel.de/planetensterne.html "Astronomische Ereignisse der besonderen Art"] {{webarchive|url=https://web.archive.org/web/20050316042622/http://www.marco-peuschel.de/planetensterne.html |date=2005-03-16 }}. Retrieved July 10, 2005.</ref>  Both components are eclipsed ([[occultation|occulted]]) by the sun from about 7–9 November.<ref>[http://in-the-sky.org/skymap.php?year=2019&month=November&day=9 In the Sky] Earth astronomy reference utility showing the ecliptic and relevant date as at J2000 - present</ref> Thus the star can be viewed the whole night, crossing the sky, in early May.
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''α Librae'' ([[Latinisation of names|Latinised]] to ''Alpha Librae'') is the system's [[Bayer designation]].
''α Librae'' ([[Latinisation of names|Latinised]] to ''Alpha Librae'') is the system's [[Bayer designation]].


''Zubenelgenubi'' {{IPAc-en|,|z|u:|b|@n|E|l|dZ|@|'|n|u:|b|i}}, also rendered ''Zuben Elgenubi'', derives from the [[Arabic]] ّالزُبَانَى الجَنُوبِي ''al-zubānā al-janūbiyy'' "the southern claw", which was coined before Libra was recognized as a constellation distinct from [[Scorpius]]. The alternative name ''Kiffa Australis'' (''Elkhiffa Australis'') is a partial [[Latin]] translation of the Arabic ''al-kiffah al-janubiyyah'' ''الكفة الجنوبية'' "southern pan [of the scales]". Another name used in older astronomy texts, equivalent to "southern pan", was ''Lanx Australis''.<ref>[https://archive.org/stream/tabulaeastronom00suntgoog#page/n146/mode/2up Philippe La Hire, "Tabulae Astronomicae" (1727), see star table, page 13.]</ref>
''Zubenelgenubi'' {{IPAc-en|,|z|u:|b|@n|E|l|dZ|@|'|n|u:|b|i}}, also rendered ''Zuben Elgenubi'', derives from the [[Arabic]] ّالزُبَانَى الجَنُوبِي ''al-zubānā al-janūbiyy'' "the southern claw", which was coined before Libra was recognized as a constellation distinct from [[Scorpius]]. The alternative name ''Kiffa Australis'' (''Elkhiffa Australis'') is a partial [[Latin]] translation of the Arabic ''al-kiffah al-janubiyyah'' ''الكفة الجنوبية'' "southern pan [of the scales]". Another name used in older astronomy texts, equivalent to "southern pan", was ''Lanx Australis''.<ref name=plhta/>


In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name="WGSN">{{citation
In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name=WGSN/> to catalogue and standardize proper names for stars. The WGSN approved the name ''Zubenelgenubi'' for ''α<sup>2</sup> Librae'' on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN"/>
| url=https://www.iau.org/science/scientific_bodies/working_groups/280/
| title=IAU Working Group on Star Names (WGSN)
| publisher=[[International Astronomical Union]]
| access-date=22 May 2016 | postscript=. }}</ref> to catalogue and standardize proper names for stars. The WGSN approved the name ''Zubenelgenubi'' for ''α<sup>2</sup> Librae'' on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN"/>


In [[Chinese astronomy|Chinese]], {{lang|zh|氐宿}} ({{lang|zh-Latn|Dī Xiù}}), meaning ''[[Root (Chinese constellation)|Root]]'', refers to an [[Asterism (astronomy)|asterism]] consisting of α<sup>2</sup> Librae, [[Iota Librae|ι Librae]], [[Gamma Librae|γ Librae]] and [[Beta Librae|β Librae]].<ref>{{in lang|zh}} ''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}}.</ref> Consequently, the [[Chinese star names|Chinese name]] for α<sup>2</sup> Librae itself is {{lang|zh|氐宿一}} ({{lang|zh-Latn|Dī Xiù yī}}), "the First Star of Root".<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>
In [[Chinese astronomy|Chinese]], {{lang|zh|氐宿}} ({{lang|zh-Latn|Dī Xiù}}), meaning ''[[Root (Chinese constellation)|Root]]'', refers to an [[Asterism (astronomy)|asterism]] consisting of α<sup>2</sup> Librae, [[Iota Librae|ι Librae]], [[Gamma Librae|γ Librae]] and [[Beta Librae|β Librae]].<ref>{{in lang|zh}} ''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}}.</ref> Consequently, the [[Chinese star names|Chinese name]] for α<sup>2</sup> Librae itself is {{lang|zh|氐宿一}} ({{lang|zh-Latn|Dī Xiù yī}}), "the First Star of Root".<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>


== Properties ==
== Properties ==
<div style="float:left; width:240px; border:solid black 1px; text-align: center; margin: 8px; padding: 4px; font-size: 90%;">
{{tree chart/start}}
{{tree chart|border=1| |  |, |S1| |S1='''Aa''' }}
{{tree chart|border=0| |, |( |PA| |PA=α<sup>2</sup> Lib (70.3 days) }}
{{tree chart|border=1| |! |` |S2| |S2='''Ab''' }}
{{tree chart|border=0| |( |  |PD|  | |PD=231″&nbsp;separation }}
{{tree chart|border=1| |! |, |S3|  | |S3='''Ba''' }}
{{tree chart|border=0| |` |( |PB|  | |PB=α<sup>1</sup> Lib (16.3 years) }}
{{tree chart|border=1| |  |` |S4|  | |S4='''Bb''' }}
{{tree chart/end}}
Hierarchy of orbits in the α Librae system
</div>
Alpha Librae is about {{Convert|77|ly|pc|abbr=off|lk=on}} from the [[Sun]].  
Alpha Librae is about {{Convert|77|ly|pc|abbr=off|lk=on}} from the [[Sun]].  
The two brightest components of Alpha Librae form a [[double star]] moving together through space as [[common proper motion]] companions. They are separated in the sky by an [[angular size|angular distance]] of 231" (3'51"). The [[position angle]] of the companion is 314 degrees. The brighter of the two is a white star of [[stellar classification|spectral type]] A3, with an [[apparent magnitude]] of 2.8. Its companion is a type F4 star of apparent brightness 5.2. They are probably members of the [[Castor Moving Group]] of stars that have a similar motion through space and share a common origin some 200 million years ago.<ref name=aaa514_A98/>
The two brightest components of Alpha Librae form a [[double star]] moving together through space as [[common proper motion]] companions. They are separated in the sky by an [[angular size|angular distance]] of 231" (3'51"). The [[position angle]] of the companion is 314 degrees. The brighter of the two is a white star of [[stellar classification|spectral type]] A3, with an [[apparent magnitude]] of 2.8. Its companion is a type F4 star of apparent brightness 5.2. They are probably members of the [[Castor Moving Group]] of stars that have a similar motion through space and share a common origin some 200 million years ago.<ref name=Caballero2010/>


=== Alpha<sup>2</sup> Librae ===
=== Alpha<sup>2</sup> Librae ===
The brightest member, α<sup>2</sup> Librae, is itself a [[spectroscopic binary]] system. The components have similar masses (mass ratio of 0.92) but the primary has a rotational velocity three times higher than its companion, which could be caused by them having significantly misaligned spin axes or if the primary is a merger product.<ref name=waisberg>{{Cite journal |last1=Waisberg |first1=Idel |last2=Klein |first2=Ygal |last3=Katz |first3=Boaz |date=2023-08-23 |title=Hidden Companions to Intermediate-mass Stars. X. Solving for the Mass Ratio in the Spectroscopic Binary Zubenelgenubi = α <sup>2</sup> Librae* |journal=Research Notes of the AAS |volume=7 |issue=8 |pages=180 |doi=10.3847/2515-5172/acf28f |bibcode=2023RNAAS...7..180W |issn=2515-5172|doi-access=free }}</ref>  
The brightest member, α<sup>2</sup> Librae or α Librae A, is itself a [[spectroscopic binary]] system. The components have similar masses (mass ratio of 0.92) but the primary has a rotational velocity three times higher than its companion, which could be caused by them having significantly misaligned spin axes or if the primary is a merger product.<ref name=Waisberg2023/>
 
=== Alpha<sup>1</sup> Librae ===
=== Alpha<sup>1</sup> Librae ===
The second member, α<sup>1</sup> Librae, is separated from the primary system by around {{val|5400|ul=AU}}. It too is a spectroscopic binary with an orbital period of 5,870&nbsp;days and an [[angular separation]] of 0.383&nbsp;arcseconds; equal to about 10&nbsp;AU.  
The second member, α<sup>1</sup> Librae or α Librae B, is separated from the primary system by around {{val|5360|fmt=commas|ul=AU}}.<ref name=Waisberg2023/> It too is a spectroscopic binary with an orbital period of 5,870&nbsp;days and an [[angular separation]] of 0.383&nbsp;arcseconds;<ref name=soar2023/> equal to about 9&nbsp;au.<ref name=Waisberg2023/>
 
=== KU Librae ===
=== KU Librae ===
The system may have a fifth component, the star KU Librae at a separation of 2.6°, thus forming a hierarchical quintuple star system. KU Lib shares a similar motion through space to the Alpha Librae system, but is separated from the other stars by about a [[parsec]]. It is sufficiently close to be gravitationally bound to the other members,<ref name=aaa514_A98/> but has a substantially different [[metallicity]], making it unlikely to be physically bound to the system.<ref name=multiplicity/>
The system may have a fifth component, the star KU Librae at a separation of 2.6°, thus forming a hierarchical quintuple star system. KU Lib shares a similar motion through space to the Alpha Librae system, but is separated from the other stars by about a [[parsec]]. It is sufficiently close to be gravitationally bound to the other members,<ref name=Caballero2010/> but has a substantially different [[metallicity]], making it unlikely to be physically bound to the system.<ref name=Fuhrmann2015/>


== See also ==
== See also ==
* [[List of stars in Libra]]
* [[List of stars in Libra]]


== Notes ==
==References==
{{Notelist|notes=
<references>


{{Efn|name=radius|1=Calculated, using the [[Stefan-Boltzmann law]] and the star's [[effective temperature]] and luminosity, with respect to the [[Sun|solar]] nominal effective temperature of 5,772&nbsp;[[Kelvin|K]]:<math display="block">\sqrt{\biggl(\frac{5,772}{6,707}\biggr)^4 \cdot 10^{0.55}} = 1.40\ R_\odot.</math>}}
<ref name=SIMBAD1>{{cite simbad | title=* alf01 Lib | access-date=2007-01-23 }}</ref>


}}
<ref name=SIMBAD2>{{cite simbad | title=* alf02 Lib | access-date=2007-01-23 }}</ref>
 
<ref name=hipparcos>{{cite journal | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}</ref>
 
<ref name=Waisberg2023>{{Cite journal |last1=Waisberg |first1=Idel |last2=Klein |first2=Ygal |last3=Katz |first3=Boaz |date=2023-08-23 |title=Hidden Companions to Intermediate-mass Stars. X. Solving for the Mass Ratio in the Spectroscopic Binary Zubenelgenubi = α <sup>2</sup> Librae* |journal=Research Notes of the AAS |volume=7 |issue=8 |pages=180 |doi=10.3847/2515-5172/acf28f |bibcode=2023RNAAS...7..180W |issn=2515-5172|doi-access=free }}</ref>


==References==
<ref name=Caballero2010>{{cite journal | last1=Caballero | first1=J. A. | title=Reaching the boundary between stellar kinematic groups and very wide binaries. II. α Librae + KU Librae: a common proper motion system in Castor separated by 1.0 pc | journal=Astronomy and Astrophysics | volume=514 | page=A98 |date=May 2010 | doi=10.1051/0004-6361/200913986 | bibcode=2010A&A...514A..98C | arxiv=1001.5432 | s2cid=118875432 }}</ref>
{{reflist|refs=


<ref name=multiplicity>{{cite journal|bibcode=2015ApJ...809..107F|title=Multiplicity among F-type stars. II|journal=The Astrophysical Journal|volume=809|pages=107|last1=Fuhrmann|first1=K.|last2=Chini|first2=R.|year=2015|issue=1|doi=10.1088/0004-637X/809/1/107|s2cid=126218052 |doi-access=}}</ref>
<ref name=Fuhrmann2015>{{cite journal|bibcode=2015ApJ...809..107F|title=Multiplicity among F-type stars. II|journal=The Astrophysical Journal|volume=809|pages=107|last1=Fuhrmann|first1=K.|last2=Chini|first2=R.|year=2015|issue=1|doi=10.1088/0004-637X/809/1/107|s2cid=126218052 |doi-access=}}</ref>


<ref name=aaa474_2_653>{{citation | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}</ref>
<ref name=soar2023>{{cite journal |last1=Tokovinin |first1=Andrei |last2=Mason |first2=Brian D. |last3=Mendez |first3=Rene A. |last4=Costa |first4=Edgardo |title=Speckle Interferometry at SOAR Telescope in 2023 |journal=The Astronomical Journal |year=2024 |volume=168 |issue=1 |page=28 |doi=10.3847/1538-3881/ad4d56 |bibcode=2024AJ....168...28T |doi-access=free}}</ref>


<ref name=apj132_1_161>{{citation | display-authors=1 | last1=Gray | first1=R. O. | last2=Corbally | first2=C. J. | last3=Garrison | first3=R. F. | last4=McFadden | first4=M. T. | last5=Bubar | first5=E. J. | last6=McGahee | first6=C. E. | last7=O'Donoghue | first7=A. A. | last8=Knox | first8=E. R. | title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample | journal=The Astronomical Journal | volume=132 | issue=1 | pages=161–170 |date=July 2006 | doi=10.1086/504637 | bibcode=2006AJ....132..161G |arxiv = astro-ph/0603770 | s2cid=119476992 }}</ref>
<ref name=tic>{{cite journal |last1=Stassun |first1=Keivan G. |last2=Oelkers |first2=Ryan J. |last3=Paegert |first3=Martin |last4=Torres |first4=Guillermo |last5=Pepper |first5=Joshua |last6=De Lee |first6=Nathan |last7=Collins |first7=Kevin |last8=Latham |first8=David W. |last9=Muirhead |first9=Philip S. |last10=Chittidi |first10=Jay |last11=Rojas-Ayala |first11=Bárbara |last12=Fleming |first12=Scott W. |last13=Rose |first13=Mark E. |last14=Tenenbaum |first14=Peter |last15=Ting |first15=Eric B. |last16=Kane |first16=Stephen R. |last17=Barclay |first17=Thomas |last18=Bean |first18=Jacob L. |last19=Brassuer |first19=C. E. |last20=Charbonneau |first20=David |last21=Ge |first21=Jian |last22=Lissauer |first22=Jack J. |last23=Mann |first23=Andrew W. |last24=McLean |first24=Brian |last25=Mullally |first25=Susan |last26=Narita |first26=Norio |last27=Plavchan |first27=Peter |last28=Ricker |first28=George R. |last29=Sasselov |first29=Dimitar |last30=Seager |first30=S. |display-authors=1 |title=The Revised TESS Input Catalog and Candidate Target List |journal=The Astronomical Journal |date=2019 |volume=158 |issue=4 |page=138 |doi=10.3847/1538-3881/ab3467 |doi-access=free |arxiv=1905.10694 |bibcode=2019AJ....158..138S }}</ref>


<ref name=aaa501_3_941>{{citation | last1=Holmberg | first1=J. | last2=Nordström | first2=B. | last3=Andersen | first3=J. | title=The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics | journal=Astronomy and Astrophysics | volume=501 | issue=3 | pages=941–947 |date=July 2009 | doi=10.1051/0004-6361/200811191 | bibcode=2009A&A...501..941H |arxiv = 0811.3982 | s2cid=118577511 }}</ref>
<ref name=Gray2006>{{cite journal | display-authors=1 | last1=Gray | first1=R. O. | last2=Corbally | first2=C. J. | last3=Garrison | first3=R. F. | last4=McFadden | first4=M. T. | last5=Bubar | first5=E. J. | last6=McGahee | first6=C. E. | last7=O'Donoghue | first7=A. A. | last8=Knox | first8=E. R. | title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample | journal=The Astronomical Journal | volume=132 | issue=1 | pages=161–170 |date=July 2006 | doi=10.1086/504637 | bibcode=2006AJ....132..161G |arxiv = astro-ph/0603770 | s2cid=119476992 }}</ref>


<ref name=sps1966>{{citation | display-authors=1 | last1=Gutierrez-Moreno | first1=Adelina | last2=Moreno | first2=H. | last3=Stock | first3=J. | last4=Torres | first4=C. | last5=Wroblewski | first5=H. | title=A System of photometric standards | journal=Publ. Dept. Astron. Univ. Chile | publisher=Publicaciones Universidad de Chile, Department de Astronomy | volume=1 | pages=1–17 | date=1966 | bibcode=1966PDAUC...1....1G }}</ref>
<ref name=Holmerg2009>{{cite journal | last1=Holmberg | first1=J. | last2=Nordström | first2=B. | last3=Andersen | first3=J. | title=The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics | journal=Astronomy and Astrophysics | volume=501 | issue=3 | pages=941–947 |date=July 2009 | doi=10.1051/0004-6361/200811191 | bibcode=2009A&A...501..941H |arxiv = 0811.3982 | s2cid=118577511 }}</ref>


<ref name=SIMBAD1>{{cite simbad | title=* alf01 Lib | access-date=2007-01-23 }}</ref>
<ref name=Zorec2012>{{Cite journal |last=Zorec |first=J. |last2=Royer |first2=F. |date=January 2012 |title=Rotational velocities of A-type stars. IV. Evolution of rotational velocities |bibcode=2012A&A...537A.120Z |journal=Astronomy and Astrophysics |language=en |volume=537 |pages=A120 |doi=10.1051/0004-6361/201117691 |issn=0004-6361}}</ref>


<ref name=SIMBAD2>{{cite simbad | title=* alf02 Lib | access-date=2007-01-23 }}</ref>
<ref name=Takeda2018>{{Cite journal |last=Takeda |first=Yoichi |last2=Kawanomoto |first2=Satoshi |last3=Ohishi |first3=Naoko |last4=Kang |first4=Dong-Il |last5=Lee |first5=Byeong-Cheol |last6=Kim |first6=Kang-Min |last7=Han |first7=Inwoo |date=October 2018 |title=Photospheric carbon, nitrogen, and oxygen abundances of A-type main-sequence stars |bibcode=2018PASJ...70...91T |journal=Publications of the Astronomical Society of Japan |language=en |volume=70 |issue=5 |pages=91 |doi=10.1093/pasj/psy091 |issn=0004-6264}}</ref>


<ref name=aaa514_A98>{{citation | last1=Caballero | first1=J. A. | title=Reaching the boundary between stellar kinematic groups and very wide binaries. II. α Librae + KU Librae: a common proper motion system in Castor separated by 1.0 pc | journal=Astronomy and Astrophysics | volume=514 | page=A98 |date=May 2010 | doi=10.1051/0004-6361/200913986 | bibcode=2010A&A...514A..98C | arxiv=1001.5432 | s2cid=118875432 }}</ref>
<ref name=sps1966>{{cite journal | display-authors=1 | last1=Gutierrez-Moreno | first1=Adelina | last2=Moreno | first2=H. | last3=Stock | first3=J. | last4=Torres | first4=C. | last5=Wroblewski | first5=H. | title=A System of photometric standards | journal=Publ. Dept. Astron. Univ. Chile | publisher=Publicaciones Universidad de Chile, Department de Astronomy | volume=1 | pages=1–17 | date=1966 | bibcode=1966PDAUC...1....1G }}</ref>


<ref name="luck">{{Citation |last=Luck |first=R. Earle |date=2018-03-01 |title=Abundances in the Local Region. III. Southern F, G, and K Dwarfs |bibcode=2018AJ....155..111L |journal=The Astronomical Journal |volume=155 |issue=3 |pages=111 |doi=10.3847/1538-3881/aaa9b5 |doi-access=free |issn=0004-6256}} [https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/AJ/155/111&ID=*%20alf01%20Lib Alpha1 Librae's database entry] at [[VizieR]].</ref>
<ref name=Luck2017>{{Cite journal |last=Luck |first=R. Earle |date=2018-03-01 |title=Abundances in the Local Region. III. Southern F, G, and K Dwarfs |bibcode=2018AJ....155..111L |journal=The Astronomical Journal |volume=155 |issue=3 |pages=111 |doi=10.3847/1538-3881/aaa9b5 |doi-access=free |issn=0004-6256}} [https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/AJ/155/111&ID=*%20alf01%20Lib Alpha1 Librae's database entry] at [[VizieR]].</ref>


<ref name=mk>{{cite journal|bibcode=1988mcts.book.....H|title=Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0|journal=Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4|last1=Houk|first1=N.|last2=Smith-Moore|first2=M.|year=1988}}</ref>
<ref name=mk>{{cite journal|bibcode=1988mcts.book.....H|title=Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0|journal=Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4|last1=Houk|first1=N.|last2=Smith-Moore|first2=M.|year=1988}}</ref>


<ref name=orbit>{{cite journal|bibcode=2014MNRAS.437.2303F|title=On the bright A-type star Alpha Librae A|journal=Monthly Notices of the Royal Astronomical Society|volume=437|issue=3|pages=2303|last1=Fuhrmann|first1=K.|last2=Chini|first2=R.|last3=Barr|first3=A.|last4=Buda|first4=L.-S.|last5=Kaderhandt|first5=L.|last6=Pozo|first6=F.|last7=Ramolla|first7=M.|year=2014|doi=10.1093/mnras/stt2046|doi-access=free}}</ref>
<ref name=Fuhrmann2014>{{cite journal|bibcode=2014MNRAS.437.2303F|title=On the bright A-type star Alpha Librae A|journal=Monthly Notices of the Royal Astronomical Society|volume=437|issue=3|pages=2303|last1=Fuhrmann|first1=K.|last2=Chini|first2=R.|last3=Barr|first3=A.|last4=Buda|first4=L.-S.|last5=Kaderhandt|first5=L.|last6=Pozo|first6=F.|last7=Ramolla|first7=M.|year=2014|doi=10.1093/mnras/stt2046|doi-access=free}}</ref>


<ref name=Koennen1981>{{cite journal
<ref name=Koennen1981>{{cite journal
Line 180: Line 206:
  | bibcode=1981JBAA...91..148K }}</ref>
  | bibcode=1981JBAA...91..148K }}</ref>


}}
<ref name=ap1999>{{cite journal |last1=Allende Prieto |first1=C. |last2=Lambert |first2=D. L. |title=Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures |journal=Astronomy and Astrophysics |date=1999 |volume=352 |page=555 |arxiv=astro-ph/9911002 |bibcode=1999A&A...352..555A }}</ref>
 
<ref name=plhta>[https://archive.org/stream/tabulaeastronom00suntgoog#page/n146/mode/2up Philippe La Hire, "Tabulae Astronomicae" (1727), see star table, page 13.]</ref>
 
<ref name=Kunitzsch>{{cite book
  |last1=Kunitzsch |first1=Paul
  |last2=Smart |first2=Tim
  |date = 2006  |edition = 2nd rev.
  |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
  |publisher = Sky Pub |location = Cambridge, Massachusetts
  |isbn = 978-1-931559-44-7
}}</ref>
 
<ref name=IAU-CSN>{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref>
 
<ref name=EgUBV>{{cite journal|author1=Mermilliod, J.-C.|title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)|journal=Catalogue of Eggen's UBV Data|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1|date=1986|bibcode= 1986EgUBV........0M }}</ref>
 
<ref name=WGSN>{{cite web
| url=https://www.iau.org/science/scientific_bodies/working_groups/280/
| title=IAU Working Group on Star Names (WGSN)
| publisher=[[International Astronomical Union]]
| access-date=22 May 2016 }}</ref>
 
</references>


==External links==
==External links==
*Kaler, Jim (2004). [https://web.archive.org/web/20050818161632/http://www.astro.uiuc.edu/~kaler/sow/zubenel.html "STARS: Zubenelgenubi"]. Retrieved July 10, 2005.
*Kaler, Jim (2004). [https://web.archive.org/web/20050818161632/http://www.astro.uiuc.edu/~kaler/sow/zubenel.html "STARS: Zubenelgenubi"]. Retrieved July 10, 2005.
* {{WikiSky}}
* {{WikiSky}}
{{Sky|14|50|41.26|-|15|59|49.5|77}}


{{Stars of Libra}}
{{Stars of Libra}}
{{Sky|14|50|41.26|-|15|59|49.5|77}}


{{DEFAULTSORT:Alpha Librae}}
[[Category:Bayer objects|Librae, Alpha]]
[[Category:Bayer objects|Librae, Alpha]]
[[Category:Binary stars]]
[[Category:Multiple star systems]]
[[Category:Libra (constellation)]]
[[Category:Libra (constellation)]]
[[Category:A-type subgiants]]
[[Category:A-type main-sequence stars]]
[[Category:F-type main-sequence stars]]
[[Category:F-type main-sequence stars]]
[[Category:M-type main-sequence stars]]
[[Category:Stars with proper names|Zubenelgenubi]]
[[Category:Stars with proper names|Zubenelgenubi]]
[[Category:Castor Moving Group]]
[[Category:Castor Moving Group]]
Line 203: Line 252:
[[Category:Durchmusterung objects|BD-15 3965]]
[[Category:Durchmusterung objects|BD-15 3965]]
[[Category:Am stars]]
[[Category:Am stars]]
[[Category:A-type main-sequence stars]]

Latest revision as of 13:13, 30 December 2025

Template:Short description

α Librae
Template:Location mark
Location of α Librae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Libra
α1 Lib (α Lib B)
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) +5.153[2]
α2 Lib (α Lib A)
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) +2.741[2]
Characteristics
α1 Lib
Spectral type F3 V[3] + M0
  1. REDIRECT Template:En dash

Template:R protected1 V[4]

U−B Template:Engvar −0.02[5]
B−V Template:Engvar +0.39[5]
α2 Lib
Evolutionary stage Main sequence[6][7] or blue straggler (α2 A)[8]
Spectral type kA2hA5mA4 IV-V[9]
U−B Template:Engvar +0.10[5]
B−V Template:Engvar +0.15[5]
Astrometry
α1 Lib
Radial velocity (Rv)Script error: No such module "val".[10] km/s
Proper motion (μ) RA: −136.27[1] mas/yr
Dec.: −59.04[1] mas/yr
Parallax (π)43.52±0.43 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+3.35[11]
α2 Lib
Proper motion (μ) RA: −105.68[1] mas/yr
Dec.: −68.40[1] mas/yr
Parallax (π)43.03±0.19 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+0.88[12]
Orbit[13]
Primaryα1 Lib A
Companionα1 Lib B
Period (P)Script error: No such module "val". yr
Semi-major axis (a)Script error: No such module "val".″
Eccentricity (e)Script error: No such module "val".
Inclination (i)Script error: No such module "val".°
Longitude of the node (Ω)Script error: No such module "val".°
Periastron epoch (T)Script error: No such module "val".
Argument of periastron (ω)
(secondary)		Script error: No such module "val".°
Semi-amplitude (K1)
(primary)		Script error: No such module "val". km/s
Orbit[10]
Primaryα2 Lib A
Companionα2 Lib B
Period (P)Script error: No such module "val". days
Semi-major axis (a)0.52[8] au
Eccentricity (e)Script error: No such module "val".
Inclination (i)Script error: No such module "val".[8]°
Longitude of the node (Ω)Script error: No such module "val".[8]°
Periastron epoch (T)JD Script error: No such module "val".
Argument of periastron (ω)
(secondary)		Script error: No such module "val".°
Semi-amplitude (K2)
(secondary)		Script error: No such module "val". km/s
Details
α1 Lib A
Mass1.95[8] Template:Solar mass
Radius2.21[8] Template:Solar radius
Surface gravity (log g)3.91[9] cgs
Temperature8,200[8] K
Age700[8] Myr
α1 Lib B
Mass1.79[8] Template:Solar mass
Radius1.92[8] Template:Solar radius
Temperature7,930[8] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Age700[8] Myr
α2 Lib A
MassScript error: No such module "val".[14] Template:Solar mass
Radius1.50[15] Template:Solar radius
Luminosity3.83[14] Template:Solar luminosity
Surface gravity (log g)4.23[14] cgs
TemperatureScript error: No such module "val".[14] K
Metallicity [Fe/H]−0.03[14] dex
Rotational velocity (v sin i)5.95[14] km/s
AgeScript error: No such module "val".[14] Gyr
α2 Lib B
Mass0.5–0.6[4] Template:Solar mass
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist
α Lib B: Template:Odlist[16]
α Lib A: Template:Odlist[17]
Database references
SIMBADα1 Lib
α2 Lib

Script error: No such module "Check for unknown parameters".

Alpha Librae (α Librae, abbreviated Alpha Lib, α Lib) is a quadruple star system and, despite its 'alpha' designation, it is the second-brightest star in the constellation of Libra. The two components are designated α1 Librae and α2 Librae. The system bore the traditional name of Zubenelgenubi Template:IPAc-en,[18] though the International Astronomical Union now regards that name as only applying to α2 Librae.[19]

Alpha2 Librae is 0.33 degrees north of the ecliptic so it can be occulted by the Moon and (very rarely) by planets. It was occulted by Venus on October 25, 1947;[20] the next occultation by a planet will be by Mercury on 10 November 2052.[21] Both components are eclipsed (occulted) by the sun from about 7–9 November.[22] Thus the star can be viewed the whole night, crossing the sky, in early May.

Nomenclature

α Librae (Latinised to Alpha Librae) is the system's Bayer designation.

Zubenelgenubi Template:IPAc-en, also rendered Zuben Elgenubi, derives from the Arabic ّالزُبَانَى الجَنُوبِي al-zubānā al-janūbiyy "the southern claw", which was coined before Libra was recognized as a constellation distinct from Scorpius. The alternative name Kiffa Australis (Elkhiffa Australis) is a partial Latin translation of the Arabic al-kiffah al-janubiyyah الكفة الجنوبية "southern pan [of the scales]". Another name used in older astronomy texts, equivalent to "southern pan", was Lanx Australis.[23]

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[24] to catalogue and standardize proper names for stars. The WGSN approved the name Zubenelgenubi for α2 Librae on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.[19]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Root, refers to an asterism consisting of α2 Librae, ι Librae, γ Librae and β Librae.[25] Consequently, the Chinese name for α2 Librae itself is Script error: No such module "Lang". (Script error: No such module "Lang".), "the First Star of Root".[26]

Properties

Script error: No such module "Tree chart".Script error: No such module "Tree chart".Script error: No such module "Tree chart".Script error: No such module "Tree chart".Script error: No such module "Tree chart".Script error: No such module "Tree chart".Script error: No such module "Tree chart".

Hierarchy of orbits in the α Librae system

Alpha Librae is about Script error: No such module "convert". from the Sun. The two brightest components of Alpha Librae form a double star moving together through space as common proper motion companions. They are separated in the sky by an angular distance of 231" (3'51"). The position angle of the companion is 314 degrees. The brighter of the two is a white star of spectral type A3, with an apparent magnitude of 2.8. Its companion is a type F4 star of apparent brightness 5.2. They are probably members of the Castor Moving Group of stars that have a similar motion through space and share a common origin some 200 million years ago.[4]

Alpha2 Librae

The brightest member, α2 Librae or α Librae A, is itself a spectroscopic binary system. The components have similar masses (mass ratio of 0.92) but the primary has a rotational velocity three times higher than its companion, which could be caused by them having significantly misaligned spin axes or if the primary is a merger product.[8]

Alpha1 Librae

The second member, α1 Librae or α Librae B, is separated from the primary system by around Script error: No such module "val"..[8] It too is a spectroscopic binary with an orbital period of 5,870 days and an angular separation of 0.383 arcseconds;[13] equal to about 9 au.[8]

KU Librae

The system may have a fifth component, the star KU Librae at a separation of 2.6°, thus forming a hierarchical quintuple star system. KU Lib shares a similar motion through space to the Alpha Librae system, but is separated from the other stars by about a parsec. It is sufficiently close to be gravitationally bound to the other members,[4] but has a substantially different metallicity, making it unlikely to be physically bound to the system.[27]

See also

References

  1. ↑ a b c d e f g h i j Script error: No such module "Citation/CS1".
  2. ↑ a b Script error: No such module "Citation/CS1".
  3. ↑ Script error: No such module "Citation/CS1".
  4. ↑ a b c d Script error: No such module "Citation/CS1".
  5. ↑ a b c d Script error: No such module "Citation/CS1".
  6. ↑ Script error: No such module "Citation/CS1".
  7. ↑ Script error: No such module "Citation/CS1".
  8. ↑ a b c d e f g h i j k l m n o Script error: No such module "Citation/CS1".
  9. ↑ a b Script error: No such module "Citation/CS1".
  10. ↑ a b Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "Citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ a b Script error: No such module "Citation/CS1".
  14. ↑ a b c d e f g Script error: No such module "Citation/CS1". Alpha1 Librae's database entry at VizieR.
  15. ↑ Script error: No such module "Citation/CS1".
  16. ↑ Template:Cite simbad
  17. ↑ Template:Cite simbad
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ a b Script error: No such module "citation/CS1".
  20. ↑ Script error: No such module "Citation/CS1".
  21. ↑ Peuschel, Marco (2003). "Astronomische Ereignisse der besonderen Art" Template:Webarchive. Retrieved July 10, 2005.
  22. ↑ In the Sky Earth astronomy reference utility showing the ecliptic and relevant date as at J2000 - present
  23. ↑ Philippe La Hire, "Tabulae Astronomicae" (1727), see star table, page 13.
  24. ↑ Script error: No such module "citation/CS1".
  25. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  26. ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.
  27. ↑ Script error: No such module "Citation/CS1".

External links

Template:Stars of Libra Template:Sky

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