Eta Boötis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 13h 54m 41.07892s |
| Declination | +18° 23′ 51.7946″ |
| Apparent magnitude (V) | 2.680 |
| Characteristics | |
| Spectral type | G0 IV |
| U−B color index | +0.207 |
| B−V color index | +0.585 |
| Astrometry | |
| Radial velocity (Rv) | −5.254±0.009 km/s |
| Proper motion (μ) | RA: −60.95 mas/yr Dec.: −356.29 mas/yr |
| Parallax (π) | 87.75±1.24 mas |
| Distance | 37.2 ± 0.5 ly (11.4 ± 0.2 pc) |
| Absolute magnitude (MV) | 2.41 |
| Details | |
| Mass | 1.71±0.05 M☉ |
| Radius | 2.659±0.044 R☉ |
| Luminosity | 8.758±0.261 L☉ |
| Surface gravity (log g) | 3.794±0.034 cgs |
| Temperature | 6,161±18 K |
| Metallicity [Fe/H] | +0.25±0.01 dex |
| Rotational velocity (v sin i) | 11.8 km/s |
| Age | 2.7 Gyr |
| Other designations | |
| Muphrid, Saak, 8 Boötis, BD+19°2725, FK5 513, GC 18805, GJ 534, HD 121370, HIP 67927, HR 5235, SAO 100766, PPM 130166, WDS J13547+1824, LTT 14060 | |
| Database references | |
| SIMBAD | data |
Eta Boötis is a candidate binary star system in the constellation of Boötes. Its name is a Bayer designation that is Latinized from η Boötis, and abbreviated Eta Boo or η Boo. This system is visible to the naked eye as a point of light with an apparent visual magnitude of 2.68. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 37 light-years (11 pc) distant from the Sun. It is drifting closer with a radial velocity of −5.3 km/s.
Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It forms a double star with the star BD+19 2726. As a constituent of a double pair, Eta Boötis is also designated WDS J13547+1824A, with its two components being designated Aa (formally named Muphrid /ˈmjuːfrɪd/, the traditional name for the entire system) and Ab. (As part of a binary pair, they are also designated Eta Boötis A and B, respectively.) BD +19 2726 is also designated WDS J13547+1824B.