Its two components are designated Beta Aquilae A (formally named Alshain/ælˈʃeɪn/, the traditional name for the system)[13][14] and B.
Nomenclature
In this
starfield showing many stars of Aquila constellation, the
asterismα, 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).[15]
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
Persianšāhīn tarāzū (or possibly šāhīn tara zed; see
Gamma Aquilae), the Persian name for the
asterismα, β and
γ Aquilae.[citation needed] In 2016, the IAU organized a
Working Group on Star Names (WGSN)[16] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire
multiple systems.[17] 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.[14]
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.[18]
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.[21] The activity shows a cycle of 969±27 d.[10] Since 1943, the
spectrum of this star has served as one of the stable anchor points by which other stars are classified.[22] This is an aging
subgiant star that has exhausted the supply of hydrogen at its core and is
evolving into a
giant.[10] It has a mass 26% greater than
the Sun's,[9] a luminosity six times that
of the Sun, and a radius about thrice
solar.[8]
^
abMontes, D.; et al. (September 2018), "Calibrating the metallicity of M dwarfs in wide physical binaries with F-, G-, and K-primaries - I: High-resolution spectroscopy with HERMES: stellar parameters, abundances, and kinematics", Monthly Notices of the Royal Astronomical Society, 479 (1): 1332–1382,
arXiv:1805.05394,
Bibcode:
2018MNRAS.479.1332M,
doi:
10.1093/mnras/sty1295.
^
abOja, T. (August 1986), "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series, 65 (2): 405–4,
Bibcode:
1986A&AS...65..405O.
^
abcButkovskaya, Varvara; et al. (February 2018), "Long-term stellar magnetic field study at the Crimean Astrophysical Observatory", Long-term Datasets for the Understanding of Solar and Stellar Magnetic Cycles, Proceedings of the International Astronomical Union, IAU Symposium, vol. 340, pp. 35–38,
Bibcode:
2018IAUS..340...35B,
doi:
10.1017/S1743921318001035,
S2CID125610540.
^Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub.
ISBN978-1-931559-44-7.
^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].
^Andretta, V.; et al. (February 2005), "The Ca II Infrared Triplet as a stellar activity diagnostic . I. Non-LTE photospheric profiles and definition of the RIRT indicator", Astronomy and Astrophysics, 430 (2): 669–677,
Bibcode:
2005A&A...430..669A,
doi:10.1051/0004-6361:20041745.
^Mudrooroo (1994). Aboriginal mythology : an A-Z spanning the history of aboriginal mythology from the earliest legends to the present day. London:
HarperCollins. p. 4.
ISBN1-85538-306-3.