Alpha Librae

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

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

Retrieved from "http://debianws.lexgopc.com/wiki143/index.php?title=Alpha_Librae&oldid=5137357"