Epsilon Boötis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 44m 59.218s |
| Declination | +27° 04′ 27.2″ |
| Apparent magnitude (V) | 2.45/4.8 |
| Characteristics | |
| Evolutionary stage | red giant branch |
| Spectral type | K0 II-III + A2 V |
| U−B color index | +0.73 |
| B−V color index | +0.97 |
| Astrometry | |
| Radial velocity (Rv) | −16.31 km/s |
| Proper motion (μ) | RA: −50.818 mas/yr Dec.: +21.024 mas/yr |
| Parallax (π) | 13.8267±0.4896 mas |
| Distance | 236 ± 8 ly (72 ± 3 pc) |
| Absolute magnitude (MV) | −1.61 |
| Details | |
| A | |
| Mass | 4.6 M☉ |
| Radius | 37.61+1.29 −1.38 R☉ |
| Luminosity | 652.5±58.7 L☉ |
| Surface gravity (log g) | 2.24 cgs |
| Temperature | 4,755±46 K |
| Metallicity [Fe/H] | −0.13 dex |
| Rotational velocity (v sin i) | 10.9 km/s |
| B | |
| Mass | 2.27 M☉ |
| Radius | 2.7 R☉ |
| Luminosity | 44.8 L☉ |
| Surface gravity (log g) | 3.9 cgs |
| Temperature | 9,009 K |
| Metallicity [Fe/H] | −0.20 dex |
| Rotational velocity (v sin i) | 123 km/s |
| Other designations | |
| Izar, Pulcherrima, Mirac, Mirak, Mirach, ε Boo, 36 Boo, BD+27°2417, HIP 72105 | |
| A: Izar, HD 129989, HR 5506, SAO 83500 | |
| B: HD 129988, HR 5505 | |
| Database references | |
| SIMBAD | Epsilon Boo A |
| Epsilon Boo B | |
Epsilon Boötis is a binary star system in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from ε Boötis, and abbreviated Epsilon Boo or ε Boo. The primary component has the official named Izar, pronounced /ˈaɪzɑːr/ (EYE-zar). The star system can be viewed with the unaided eye at night, but resolving the pair with a small telescope is challenging; an aperture of 76 mm (3.0 in) or greater is required. Based on parallax measurements, it is located at a distance of 236 light-years (72 pc). The system is drifting closer to the Sun with a radial velocity of −16 km/s.