Eta Ursae Minoris
|
Star η Ursae Minoris |
|||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||
| AladinLite | |||||||||||||||||||
|
Observation dates equinox : J2000.0 , epoch : J2000.0 |
|||||||||||||||||||
| 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 |
||||||||||||||||||
| 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 ☉ |
||||||||||||||||||
| Effective temperature | 6400 K | ||||||||||||||||||
| Rotation time | 12 hours | ||||||||||||||||||
|
Other names and catalog entries |
|||||||||||||||||||
|
|||||||||||||||||||
| annotation | |||||||||||||||||||
|
|||||||||||||||||||
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.