Beta Draconis

Rastaban, β Dra

Location of β Draconis (bottom left).
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Draco
Right ascension 17h 30m 25.9620s[1]
Declination +52° 18′ 04.994″[1]
Apparent magnitude (V) 2.79[1]
Characteristics
Spectral type G2III:[1]
U−B color index +0.64[2]
B−V color index +0.98[2]
R−I color index +0.48[2]
Astrometry
Radial velocity (Rv) −20.0 ± 0.9[1] km/s
Proper motion (μ) RA: −15.59[1] mas/yr
Dec.: 11.57[1] mas/yr
Parallax (π) 9.02 ± 0.49[1] mas
Distance 360 ± 20 ly
(111 ± 6 pc)
Absolute magnitude (MV) −2.4[3]
Details
Mass 5[4] M☉
Radius 40[4] R☉
Luminosity 950[4] L☉
Temperature 5100[4] K
Rotational velocity (v sin i) 13[2] km/s
Other designations
Rastaban, Rastaben, Alwaid, Asuia, β Dra, Beta Draconis, Beta Dra, 23 Draconis, 23 Dra, BD+52 2065, FK5 653, HD 159181, HIP 85670, HR 6536, SAO 30429, WDS 17304+5218A.[1][2][5]
Database references
SIMBAD data

Beta Draconis (Beta Dra, β Draconis, β Dra) is the third brightest star in the constellation of Draco. It has the traditional name Rastaban, which has also been used for Gamma Draconis.[4][6]

It is a G-type giant star, with spectral class G2 and an apparent visual magnitude of approximately 2.79. Its distance from the Sun is around 360 light years.[1] It is a binary star, with a binary star designation of ADS 10611, in which the supergiant is orbited by a dwarf companion once every four millennia or so.[1][4]

Name

The traditional name, from the Arabic phrase ra's ath-thu'ban ("head of the serpent") is less commonly written Rastaben. It is also known as Asuia and Alwaid, the latter meaning "who is to be destroyed," though some trace it to Arabic al'awwad ("the lute player"). It is part of the asterism of the Mother Camels (Arabic al'awa'id), along with γ Dra (Eltanin), μ Dra (Erakis) ν Dra (Kuma) and ξ Dra (Grumium), which was later known as the Quinque Dromedarii.[7]

In Chinese, 天棓 (Tiān Bàng), meaning Celestial Flail, refers to an asterism consisting of β Draconis, ξ Draconis, ν Draconis, γ Draconis and ι Herculis.[8] Consequently, β Draconis itself is known as 天棓三 (Tiān Bàng sān, English: the Third Star of Celestial Flail.)[6][9][10]

References

  1. ^ a b c d e f g h i j k * bet Dra -- Star in double system, database entry, SIMBAD. Accessed on line September 17, 2008.
  2. ^ a b c d e HR 6536, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 17, 2008.
  3. ^ From apparent magnitude and parallax.
  4. ^ a b c d e f Rastaban, Stars, Jim Kaler. Accessed on line September 17, 2008.
  5. ^ Entry 17304+5218, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 17, 2008.
  6. ^ a b pp. 207–208, Star-names and Their Meanings, Richard Hinckley Allen, New York, London: G. E. Stechert, 1899.
  7. ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 207. ISBN 0486210790. http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Draco*.html. Retrieved 2010-12-12. 
  8. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 9789867332257.
  9. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  10. ^ Alwaid, Constellations of Words, Anne Wright. Accessed on line September 17, 2008.

External links

Stars of Draco
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