Η Ursae Minoris
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| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
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|---|---|
| Constellation | Ursa Minor |
| Right ascension | 16h 17m 30.28696s |
| Declination | +75° 45′ 19.1885″ |
| Apparent magnitude (V) | +4.95 |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | F5 V |
| U−B color index | +0.02 |
| B−V color index | +0.35 |
| Astrometry | |
| Radial velocity (Rv) | −11.0±0.9 km/s |
| Proper motion (μ) |
RA: −90.30 mas/yr Dec.: +257.66 mas/yr |
| Parallax (π) | 33.63 ± 0.17mas |
| Distance | 97.0 ± 0.5 ly (29.7 ± 0.2 pc) |
| Absolute magnitude (MV) | +2.61 |
| Details | |
| Mass | 1.35 M☉ |
| Surface gravity (log g) | 4.15±0.14 cgs |
| Temperature | 6,858±233 K |
| Metallicity [Fe/H] | −0.02 dex |
| Rotational velocity (v sin i) | 84.8 km/s |
| Age | 1.061 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Ursae Minoris, Latinized from η Ursae Minoris, is a yellow-white hued star in the northern circumpolar constellation of Ursa Minor. It has been called Anwar al Farkadain, from the Arabic انور الفرقدين ’anwar al-farqadayn, meaning "the brighter of the two calves". It is then paired with ζ Ursae Minoris as Akhfa al Farkadain اخفي الفرقدين, "the dimmer of the two calves". The names may originally refer to a pair of Ibexes, and are more properly applied to β UMi and γ UMi respectively, the brighter two stars in the rectangle of Ursa Minor.
This is an F-type main-sequence star of stellar classification F5 V with an apparent magnitude of +4.95, making it faintly visible to the naked eye. Based upon an annual parallax shift of 33.63 mas as seen from the Earth, it is located 97 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −11 km/s, and is traversing the sky with a relatively high proper motion of 0.271 arc seconds per year.
Eta Ursae Minoris is about one billion years old and has an estimated 1.35 times the mass of the Sun. It has a high rate of spin with a projected rotational velocity of 84.8 km/s. These coordinates mark a source of X-ray emission with a luminosity of 11.5×1028 erg s−1. Eta Ursae Minoris may form a wide binary system with a magnitude 15.3 companion star, located at an angular separation of 228.5 arc seconds.
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