Eta Boötis

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Template:Short description

η Boötis
Template:Location mark
Location of η Boötis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 2.680[2]
Characteristics
Spectral type G0 IV[3]
U−B Template:Engvar +0.207[4]
B−V Template:Engvar +0.585[4]
Astrometry
Radial velocity (Rv)−5.254±0.009[5] km/s
Proper motion (μ) RA: −60.95[1] mas/yr[1]
Dec.: −356.29 mas/yr[1]
Parallax (π)87.75±1.24 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)2.41[2]
Details[6]
MassScript error: No such module "val".[7] Template:Solar mass
RadiusScript error: No such module "val". Template:Solar radius
LuminosityScript error: No such module "val". Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val". cgs
TemperatureScript error: No such module "val".[8] K
Metallicity [Fe/H]Script error: No such module "val".[8] dex
Rotational velocity (v sin i)11.8[9] km/s
Age2.7[3] Gyr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[10]
Database references
SIMBADdata

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Eta Boötis is a candidate binary star system in the constellation of Boötes. Its name is a Bayer designation that is Latinized from η Boötis, and abbreviated Eta Boo or η Boo. This system is visible to the naked eye as a point of light with an apparent visual magnitude of 2.68.[2] Based on parallax measurements obtained during the Hipparcos mission, it is approximately Script error: No such module "convert". distant from the Sun.[1] It is drifting closer with a radial velocity of −5.3 km/s.[5]

Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[11] It forms a double star with the star BD+19 2726.[12] As a constituent of a double pair, Eta Boötis is also designated WDS J13547+1824A, with its two components being designated Aa (formally named Muphrid Template:IPAc-en, the traditional name for the entire system)[13] and Ab. (As part of a binary pair, they are also designated Eta Boötis A and B, respectively.) BD +19 2726 is also designated WDS J13547+1824B.[12]

Nomenclature

η Boötis (Latinised to Eta Boötis) is the binary pair's Bayer designation; η Boötis A and B those of its two components. The designations of the two constituents of the double pair as WDS J13547+1824A and B and those of A's components - Aa and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[14]

Eta Boötis bore the traditional names Muphrid and Saak.[15] Muphrid is from the Arabic مفرد الرامح mufrid ar-rāmiħ "the (single) one of the lancer".[16] In 2016, the IAU organized a Working 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 entire multiple systems.[18] It approved the name Muphrid for the component WDS J13547+1824Aa (Eta Boötis A) on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.[13]

In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Ramih al Ramih (رمح الرامح rumḥ al rāmiḥ), which was translated into Latin as Lancea Lanceator, possibly meaning the lance of the lancer.[19]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning "the Right Conductor", refers to an asterism consisting of Eta Boötis, Tau Boötis and Upsilon Boötis.[20] Consequently, the Chinese name for Eta Boötis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx).[21]

Properties

Eta Boötis is a suspected spectroscopic binary with a reported period of 494 days, but the companion was not confirmed through speckle interferometry. This measurement does not rule out a low mass stellar companion of spectral class M7.[7]

Eta Boötis presents as a subgiant that has begun the process of evolving from a main sequence star into a red giant. It has about 1.7 times the mass of the Sun[7] and 2.66 times the Sun's radius.[6] The estimated age of this star is about 2.7 billion years.[3] Based on its spectra, it has a significant excess of elements heavier than helium.[2] In fact the ratio of iron to hydrogen is considered close to the upper limit for dwarf stars in the galactic disk.[22]

Eta Boötis appears close to the prominent star Arcturus (Alpha Bootis) in Earth's sky, and Arcturus is in fact its closest stellar neighbor, as both stars are nearly identical in distance from the Sun. The two stars are about 3.24 light-years apart,[23] and each would appear bright in the other's sky. Arcturus would appear as roughly magnitude -5.2 (about 120 times brighter than it appears from Earth, or close to twice the brightness of Venus) in the night sky of a hypothetical planet orbiting Eta Boötis, while Eta Boötis would appear at about magnitude −2.4 (absolute magnitude −2.41 at 0.99 parsec) in the sky of a hypothetical planet orbiting Arcturus, or over twice the brightness of Sirius in the night sky.Script error: No such module "Unsubst".

See also

References

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  1. ↑ a b c d e f Script error: No such module "Citation/CS1". Note: see VizieR catalogue I/311.
  2. ↑ a b c d Script error: No such module "Citation/CS1".
  3. ↑ a b c Script error: No such module "Citation/CS1".
  4. ↑ a b Script error: No such module "Citation/CS1".
  5. ↑ a b Script error: No such module "Citation/CS1".
  6. ↑ a b Script error: No such module "Citation/CS1".
  7. ↑ a b c Script error: No such module "Citation/CS1".
  8. ↑ a b Script error: No such module "Citation/CS1". Muphrid's database entry at VizieR.
  9. ↑ Script error: No such module "Citation/CS1".
  10. ↑ Template:Cite simbad
  11. ↑ Script error: No such module "Citation/CS1".
  12. ↑ a b Script error: No such module "citation/CS1".
  13. ↑ a b Script error: No such module "citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".
  15. ↑ Script error: No such module "Citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "citation/CS1".
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ Script error: No such module "Citation/CS1".
  20. ↑ 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.
  21. ↑ 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.
  22. ↑ Script error: No such module "Citation/CS1".
  23. ↑ Script error: No such module "citation/CS1".

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External links

Template:Stars of Boötes

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