Star in the constellation Draco
Alruba ,[ 9] Arabic for "the foal", is a suspected astrometric binary [ 10] star system in the northern circumpolar constellation of Draco . It is just barely visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.76.[ 2] parallax measurements obtained during the Gaia mission, it is located at a distance of about 457 light-years (140 parsecs ) from the Sun . The system is drifting closer with a radial velocity of −2 km/s.[ 5]
The visible component is an A-type main-sequence star with a stellar classification of A0 V.[ 4] [ 7] [ 3] mass of the Sun and has a high rate of spin, showing a projected rotational velocity of 170 km/s.[ 3] [ 3] luminosity of the Sun from its photosphere at an effective temperature of 9,226 K.[ 3] X-ray emission , which is most likely coming from the unseen companion.[ 11]
Nomenclature
In the Henry Draper catalogue HD 161693 , while it has the identifier HR 6618 in the Bright Star Catalogue [ 8]
It bore the traditional Arabic name الربع Al Rubaʽ "the foal" (specifically a young camel born in the spring), a member of the Mother Camels asterism in early Arabic astronomy .[ 12] [ 13]
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[ 14] Alruba for this star on 1 June 2018 and it is now so entered on the List of IAU-approved Star Names.[ 9]
References
^ a b c d e Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties" . Astronomy & Astrophysics 616 . A1. arXiv :1804.09365 Bibcode :2018A&A...616A...1G doi :10.1051/0004-6361/201833051 Gaia DR2 record for this source at VizieR .^ a b Oja, T. (March 1985), "UBV photometry of stars whose positions are accurately known. II", Astronomy and Astrophysics Supplement Series , 59 : 461– 464, Bibcode :1985A&AS...59..461O . ^ a b c d e f g h i Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics , 537 : A120, arXiv :1201.2052 Bibcode :2012A&A...537A.120Z , doi :10.1051/0004-6361/201117691 , S2CID 55586789 . ^ a b Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", The Astrophysical Journal Supplement Series , 99 : 135, Bibcode :1995ApJS...99..135A , doi :10.1086/192182 ^ a b Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters , 32 (11): 759– 771, arXiv :1606.08053 Bibcode :2006AstL...32..759G , doi :10.1134/S1063773706110065 , S2CID 119231169 . ^ a b Wu, Yue; et al. (2010), "Coudé-feed stellar spectral library – atmospheric parameters", Astronomy & Astrophysics , 525 : A71, arXiv :1009.1491 Bibcode :2011A&A...525A..71W , doi :10.1051/0004-6361/201015014 , S2CID 53480665 . ^ a b Gullikson, Kevin; et al. (2016), "The Close Companion Mass-Ratio Distribution of Intermediate-Mass Stars", The Astronomical Journal , 152 (2): 40, arXiv :1604.06456 Bibcode :2016AJ....152...40G , doi :10.3847/0004-6256/152/2/40 S2CID 119179065 . ^ a b "HD 161693 -- Star" , SIMBAD Astronomical Database , Centre de Données astronomiques de Strasbourg , retrieved 2018-07-01 .^ a b Naming Stars , retrieved 2018-07-01 .^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society , 389 (2): 869– 879, arXiv :0806.2878 Bibcode :2008MNRAS.389..869E , doi :10.1111/j.1365-2966.2008.13596.x S2CID 14878976 . ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics , 475 (2): 677– 684, Bibcode :2007A&A...475..677S , doi :10.1051/0004-6361:20077429 ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning New York , NY : Dover Publications Inc., pp. 207– 212, ISBN 0-486-21079-0 , retrieved 2020-01-07 .^ Garfinkle, Robert A. (2008), Star-Hopping: Your Visa to Viewing the Universe Cambridge University Press , p. 183, ISBN 978-0521598897 ^ "International Astronomical Union | IAU" , www.iau.org , retrieved 2018-07-01 .
