Beta Aquilae

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Template:Short description

Beta Aquilae
Template:Location mark
Location of β Aquilae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila[1]
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) 3.87 + 12.0[3]
Characteristics
Spectral type G9.5 IV[4] + M2.5 V[5]
U−B Template:Engvar 0.48[6]
B−V Template:Engvar 0.86[6]
R−I Template:Engvar 0.49
Variable type Suspected
Astrometry
Radial velocity (Rv)−40.3±0.09[7] km/s
Proper motion (μ) RA: +45.944 mas/yr[2]
Dec.: −480.965 mas/yr[2]
Parallax (π)73.5249±0.1415 mas[8]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+3.03[1]
Details[9]
A
MassScript error: No such module "val". Template:Solar mass
RadiusScript error: No such module "val". Template:Solar radius
Luminosity5.878±0.032[10] Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val". cgs
TemperatureScript error: No such module "val".[10] K
Metallicity [Fe/H]Script error: No such module "val".[11] dex
RotationScript error: No such module "val".[12] days
Rotational velocity (v sin i)22.28[13] km/s
AgeScript error: No such module "val". Gyr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[14]
Database references
SIMBADdata
ARICNSdata

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Beta Aquilae is a triple star[15] system in the equatorial constellation of Aquila. Its name is a Bayer designation that is Latinized from β Aquilae, and abbreviated Beta Aql or β Aql. This system is visible to the naked eye as a point-like source with an apparent visual magnitude of 3.87.[3] Based on parallax measurements, it is located at a distance of 44.4 light-years.[8] It is drifting closer to the Sun with a radial velocity of −40 km/s,[7] and is predicted to approach to within Script error: No such module "convert". in roughly 207,000 years.[16]

Its two visible components are designated Beta Aquilae A and B. The former is formally named Alshain Template:IPAc-en, the traditional name for the system.[17][18]

Nomenclature

File:Altair, Tarazed and Alshain.jpg
In this starfield showing many stars of Aquila constellation, the asterism α, β and γ Aquilae can be easily recognized on the left portion of the image.

β Aquilae (Latinised to Beta Aquilae) is the system's Bayer designation. The designations of the two components as Beta Aquilae A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[19]

The system bore the traditional name Alshain derived from the Perso-Arabic term الشاهين, aš-šāhīn, meaning "the (peregrine) falcon", perhaps by folk etymology from the Persian šāhīn tarāzū (or possibly šāhīn tara zed; see Gamma Aquilae), the Persian name for the asterism α, β and γ Aquilae.Script error: No such module "Unsubst". In 2016, the IAU organized a Working Group on Star Names (WGSN)[20] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[21] It approved the name Alshain for the component Beta Aquilae A on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[18]

In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Unuk al Ghyrab (عنق ألغراب - únuq al-ghuraab), which was translated into Latin as Collum Corvi, meaning the crow's neck.[22]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning River Drum, refers to an asterism consisting of Beta Aquilae, Altair and Gamma Aquilae.[23] Consequently, the Chinese name for Beta Aquilae itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx).[24]

Properties

The primary, component A, is of magnitude 3.71 and spectral class G8IV. It has a very low level of surface magnetic activity and may be in a state similar to a Maunder minimum.[25] The activity shows a cycle of Script error: No such module "val"..[12] The star displays solar-like oscillations.[26] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[27]

This is an aging subgiant star that has exhausted the supply of hydrogen at its core and is evolving into a giant.[12] Its angular diameter has been precisely determined using interferometry at the Very Large Telescope and the CHARA array, the average of both measurements, combined with its estimated distance, result in a radius 3.096 times the radius of the Sun. It has a mass 24% greater than the Sun's, [9] a luminosity 5.9 times that of the Sun, and an effective temperature of 5,060 K.[10]

The 12th magnitude secondary companion, designated component B, is a double-lined spectroscopic binary,[28] which is at an angular separation of 13 arcseconds from the primary. It has a stellar classification of M2.5 V,[5] matching a class M red dwarf.

In culture

In the Chinese folk tale The Cowherd and the Weaver Girl, Beta and Gamma Aquilae are children of Niulang (牛郎, The Cowherd, Altair) and Zhinü (織女, The Princess, Vega).

The Koori people of Victoria knew Beta and Gamma Aquilae as the black swan wives of Bunjil (Altair), the wedge-tailed eagle.[29]

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References

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  10. a b c Script error: No such module "citation/CS1".
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  12. a b c Script error: No such module "citation/CS1".
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  23. 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.
  24. 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 26, 2008.
  25. Script error: No such module "citation/CS1".
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External links

Template:Stars of Aquila Template:Authority control