Eta Ursae Minoris
Star η Ursae Minoris |
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AladinLite | |||||||||||||||||||
Observation dates equinox : J2000.0 , epoch : J2000.0 |
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Constellation | Little Bear | ||||||||||||||||||
Right ascension | 16 h 17 m 30.29 s | ||||||||||||||||||
declination | + 75 ° 45 ′ 19.2 ″ | ||||||||||||||||||
Apparent brightness | 4.95 likes | ||||||||||||||||||
Typing | |||||||||||||||||||
B − V color index | +0.37 | ||||||||||||||||||
U − B color index | +0.08 | ||||||||||||||||||
Spectral class | F5 V | ||||||||||||||||||
Astrometry | |||||||||||||||||||
Radial velocity | (−11.0 ± 0.9) km / s | ||||||||||||||||||
parallax | (33.63 ± 0.17) mas | ||||||||||||||||||
distance | (96.98 ± 0.49) Lj (29.74 ± 0.15) pc |
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Visual absolute brightness M vis | +2.6 mag | ||||||||||||||||||
Proper movement | |||||||||||||||||||
Rec. Share: | (−90.30 ± 0.19) mas / a | ||||||||||||||||||
Dec. portion: | (+257.66 ± 0.20) mas / a | ||||||||||||||||||
Physical Properties | |||||||||||||||||||
Dimensions | 1.4 M ☉ | ||||||||||||||||||
radius | 2 R ☉ | ||||||||||||||||||
Luminosity |
7.4 L ☉ |
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Effective temperature | 6400 K | ||||||||||||||||||
Rotation time | 12 hours | ||||||||||||||||||
Other names and catalog entries |
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η Ursae Minoris ( Eta Ursae Minoris , η UMi ) is a main sequence star in the constellation of the Little Bear. It is almost 100 light years away and is somewhat more massive and larger than the sun. With a surface temperature of 6400 Kelvin, it belongs to the spectral class F5.
Together with the red dwarf NLTT 42620 , η Ursae Minoris forms a pair of proper motions. The companion is of the spectral type M4 and has an apparent visual magnitude of 15.1 mag; its angular distance is 228 ", the position angle 125 °.
η Ursae Minoris has the historical proper names Anwar Al Farkadain and Alasco . The Arabic name ( Arabic أنور الفرقدين, DMG Anwar al-farqadain ) means “the lighter of the two calves”, originally β Ursae Minoris (Kochab), another star in the constellation, was called it. The “darker of the two calves” - Alifa al Farkadain - was initially γ Ursae Minoris (Pherkad), then the name was transferred to ζ Ursae Minoris, who is actually lighter than Anwar Al Farkadain.