Kochab
Star Kochab (β Ursae Minoris) |
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Kochab is the right corner of the "car body". | |||||||||||||||||||||
AladinLite | |||||||||||||||||||||
Observation dates equinox : J2000.0 , epoch : J2000.0 |
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Constellation | Little Bear | ||||||||||||||||||||
Right ascension | 14 h 50 m 42.33 s | ||||||||||||||||||||
declination | + 74 ° 09 ′ 19.8 ″ | ||||||||||||||||||||
Apparent brightness | 2.07 mag | ||||||||||||||||||||
Typing | |||||||||||||||||||||
B − V color index | +1.47 | ||||||||||||||||||||
U − B color index | +1.78 | ||||||||||||||||||||
R − I index | +0.76 | ||||||||||||||||||||
Spectral class | K4 III | ||||||||||||||||||||
Astrometry | |||||||||||||||||||||
Radial velocity | (+16.9 ± 0.3) km / s | ||||||||||||||||||||
parallax | (24.91 ± 0.12) mas | ||||||||||||||||||||
distance | (130.9 ± 0.6) Lj (40.14 ± 0.19) pc |
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Visual absolute brightness M vis | −1.0 mag | ||||||||||||||||||||
Proper movement | |||||||||||||||||||||
Rec. Share: | (−32.61 ± 0.11) mas / a | ||||||||||||||||||||
Dec. portion: | (11.42 ± 0.13) mas / a | ||||||||||||||||||||
Physical Properties | |||||||||||||||||||||
Dimensions | 4.4 M ☉ | ||||||||||||||||||||
radius | (41 ± 4) R ☉ | ||||||||||||||||||||
Luminosity |
500 L ☉ |
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Effective temperature | (4085 ± 140) K. | ||||||||||||||||||||
Metallicity [Fe / H] | (−0.15 ± 0.2) | ||||||||||||||||||||
Other names and catalog entries |
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Kochab (from Arabic :الكوكب, DMG al-kaukab 'the star') or β Ursae Minoris (Beta Ursae Minoris, β UMi for short) is the name of the second brightest star in the constellation Little Bear (Little Dipper). Originally it was calledالكوكب الشمالي al-kaukab asch-shamālī 'the northern star' and was considered the pole star by Arab astronomers. It hassince moved out of this positiondue to the precession of the earth.
With an apparent brightness of 2.1 mag, Kochab is easy to see with the naked eye and, together with Pherkad, forms the end of the box of the “Little Dipper”. It can be seen in the northern hemisphere up to latitude 16 ° north as a circumpolar star .
It is an orange-red giant star and belongs to spectral class K4 and luminosity class III. Its distance from the Sun is about 130 light years. Kochab is considered a single star.
See also
Web links
Individual evidence
- ↑ a b c Hipparcos catalog (ESA 1997)
- ↑ a b c Bright Star Catalog
- ↑ Pulkovo radial velocities for 35493 HIP stars
- ↑ a b c Hipparcos, the New Reduction (van Leeuwen, 2007)
- ↑ estimated from apparent brightness and distance
- ↑ JMMC Stellar Diameters Catalog - JSDC (Lafrasse +, 2010) (calculated from the data values LDD and Plx)
- ↑ a b p Dehaes, E. Bauwens, L. Decin, K. Eriksson, G. Raskin, B. Butler, CD Dowell, B. Ali, JADL Blommaert: Structure of the outer layers of cool stars standard . In: Astronomy & Astrophysics . 533, September 2011, p. A107. arxiv : 0905.1240 . bibcode : 2011A & A ... 533A.107D . doi : 10.1051 / 0004-6361 / 200912442 .