Global InformationEta Ursae Minoris information
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 16h 17m 30.27025s[1] |
| Declination | +75° 45′ 19.2351″[1] |
| Apparent magnitude (V) | +4.95[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | F5 V[4] |
| U−B color index | +0.02[2] |
| B−V color index | +0.35[2] |
| Astrometry | |
| Radial velocity (Rv) | −11.0±0.9[5] km/s |
| Proper motion (μ) | RA: −77.647[1] mas/yr Dec.: +245.726[1] mas/yr |
| Parallax (π) | 33.4190 ± 0.1103 mas[1] |
| Distance | 97.6 ± 0.3 ly (29.92 ± 0.10 pc) |
| Absolute magnitude (MV) | +2.61[6] |
| Details | |
| Mass | 1.35[7] M☉ |
| Radius | 2.0[1] R☉ |
| Luminosity | 7.7[1] L☉ |
| Surface gravity (log g) | 4.15±0.14[7] cgs |
| Temperature | 6,858±233[7] K |
| Metallicity [Fe/H] | −0.02[8] dex |
| Rotational velocity (v sin i) | 84.8[3] km/s |
| Age | 1.061[7] Gyr |
| Other designations | |
η UMi, 21 Ursae Minoris, BD+76°596, FK5 612, GC 21999, HD 148048, HIP 79822, HR 6116, SAO 8470, CCDM 16176+7545[9] | |
| 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.
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.[10] Based upon an annual parallax shift of 33.4 mas as seen from the Earth, it is located 98 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −11 km/s,[5] and is traversing the sky with a relatively high proper motion of 0.271 arc seconds per year.[11]
Eta Ursae Minoris is about one billion years old and has an estimated 1.35 times the mass of the Sun.[7] It has a high rate of spin with a projected rotational velocity of 84.8 km/s.[3] These coordinates mark a source of X-ray emission with a luminosity of 11.5×1028 erg s−1.[6] 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.[4]
In some Arabic star charts it is labeled انور الفرقدين ʼanwar al-farqadayn, "the brighter of the two calves", and paired with ζ Ursae Minoris as اخفي الفرقدين akhfā al-farkadain "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.[12]
- ^ a b c d e f g Cite error: The named reference
dr3was invoked but never defined (see the help page). - ^ a b c Cite error: The named reference
eggen1986was invoked but never defined (see the help page). - ^ a b c Cite error: The named reference
Schroeder2009was invoked but never defined (see the help page). - ^ a b Cite error: The named reference
Eggleton2008was invoked but never defined (see the help page). - ^ a b Cite error: The named reference
Gontcharov2006was invoked but never defined (see the help page). - ^ a b Cite error: The named reference
aaa361_614was invoked but never defined (see the help page). - ^ a b c d e Cite error: The named reference
David2015was invoked but never defined (see the help page). - ^ Cite error: The named reference
Casagrande2011was invoked but never defined (see the help page). - ^ Cite error: The named reference
SIMBADwas invoked but never defined (see the help page). - ^ Cite error: The named reference
kaleretawas invoked but never defined (see the help page). - ^ Cite error: The named reference
Lepine2005was invoked but never defined (see the help page). - ^ Cite error: The named reference
allenwas invoked but never defined (see the help page).