Alkaid

Database links to η Ursae Maioris

Star Alkaid (η Ursae Maioris)
η UMa in the constellation "Great Bear"
AladinLite
Observation dates equinox :  J2000.0 , epoch : J2000.0
Constellation	Big Bear
Right ascension	13 h 47 m 32.44 s
declination	+ 49 ° 18 ′ 47.8 ″
Apparent brightness	1.80 mag
Typing
B − V color index	−0.19
U − B color index	−0.68
R − I index	−0.18
Spectral class	B3 V
Astrometry
Radial velocity	(−13.4 ± 0.6) km / s
parallax	(31.38 ± 0.24)  mas
distance	(103.9 ± 0.8)  ly (31.9 ± 0.3)  pc
Visual absolute brightness M vis	−0.60 mag
Proper movement
Rec. Share:	(−121.17 ± 0.15)  mas / a
Dec. portion:	(−14.91 ± 0.17)  mas / a
Physical Properties
Dimensions	3.3  M ☉
radius	3.9  R ☉
Luminosity	460  L ☉
Effective temperature	15700  K
Metallicity [Fe / H]	−0.14
Other names and catalog entries
Bayer name η Ursae Maioris Flamsteed name 85 Ursae Maioris Bonn survey BD + 50 ° 2027 Bright Star Catalog HR 5191 [1] Henry Draper Catalog HD 120315 [2] Hipparcos catalog HIP 67301 [3] SAO catalog SAO 44752 [4] Tycho catalog TYC 3467-1257-1 [5] 2MASS catalog 2MASS J13473244 + 4918477 [6] Other names FK5 509

Alkaid (from Arabic القائد, DMG al-qāʾid  'the leader') is the proper name of the star Eta Ursae Maioris (η UMa) in the constellation Great Bear . It's at the front of the Big Dipper's drawbar . Alkaid has an apparent magnitude of 1.8 mag and is about 104 light years away.

Alkaid is a blue-and-white main sequence star about 3 times the mass, 4 times the diameter and more than 450 times the luminosity of the sun . Its surface temperature is around 15,700 K. The star rotates unusually fast; a projected equatorial rotation speed v ∙ sin i of around 160 km / s was measured for it.

Unlike most of the other stars in the Big Dipper, it does not belong to the so-called group of bears , a cluster of over a hundred stars.

In the old Arabic interpretation, the three tiller stars of the big dipper were called بنات نعش / banāt naʿš  / 'daughters of the bier' viewed, d. H. Mourners who go before the bier. The foremost of the stars was thatقائد بنات نعش / qāʾid banāt naʿš  / 'leader of the mourners'. In traditional European astronomy, the star was derived from it and called Alkaid or Benetnasch. According to the “IAU Catalog of Star Names” of the Working Group on Star Names (WGSN) of the IAU for the standardization of star names, the name “Alkaid” was officially assigned to the star η Ursae Maioris in 2016.

See also

• List of the brightest stars

Web links

• http://stars.astro.illinois.edu/sow/alkaid.html

Trivia

In allusion to the word similarity of the personal name Alkaid to al-Qāʿida , Frank-Markus Barwasser wrote the play Alkaid - Fur has the State in Bed, which premiered in 2010 at the Munich Residenztheater .

Individual evidence

1. ^ ^{A b c d} VizieR: Hipparcos, the New Reduction (van Leeuwen, 2007) - The Astrometric Catalog
2. ↑ ^{a b c} VizieR: Stellar Photometry in Johnson's 11-color system (Ducati, 2002)
3. ^ WW Morgan, PC Keenan: Spectral Classification. In: Annual Review of Astronomy and Astrophysics. Vol. 11, 1973, doi: 10.1146 / annurev.aa.11.090173.000333 , pp. 29-50, bibcode : 1973ARA & A..11 ... 29M .
4. ↑ VizieR: Pulkovo radial velocities for 35493 HIP stars (Gontcharov, 2006)
5. ↑ ^{a b c} VizieR: Fundamental parameters of stars (Allende Prieto +, 1999)
6. ↑ ^{a b} VizieR: Infrared excesses of Hipparcos stars (McDonald +, 2012)
7. ↑ VizieR: Atmospheric parameters for 1273 stars (Wu +, 2011)
8. ^ Catalog of Stellar Rotational Velocities (Glebocki + 2005) - Mean V * sin (i) values ​​for stars
9. ↑ Bulletin of the IAU Working Group on Star Names, No. 2. IAU Division C Education, Outreach and Heritage, 2016 ( PDF; 158 kB ).