| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 12h 54m 01.74959s |
| Declination | +55° 57′ 35.3627″ |
| Apparent magnitude (V) | 1.77 |
| Characteristics | |
| Spectral type | A1III-IVp kB9 |
| U−B color index | +0.02 |
| B−V color index | -0.02 |
| Variable type | α2 CVn |
| Astrometry | |
| Radial velocity (Rv) | -9.3 km/s |
| Proper motion (μ) | RA: +111.91 mas/yr Dec.: -8.24 mas/yr |
| Parallax (π) | 39.51 ± 0.20 mas |
| Distance | 82.6 ± 0.4 ly (25.3 ± 0.1 pc) |
| Absolute magnitude (MV) | –0.2 |
| Details | |
| Mass | 2.91 M☉ |
| Radius | 4.14 R☉ |
| Luminosity | 102 L☉ |
| Surface gravity (log g) | 3.23 cgs |
| Temperature | 9,020 K |
| Metallicity [Fe/H] | +0.00 dex |
| Rotational velocity (v sin i) | 33 km/s |
| Age | 300 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Alioth, also known as Epsilon Ursae Majoris, ε Ursae Majoris and shortened to Epsilon UMa or ε UMa, is a star located in the northern constellation of Ursa Major 81 light years away from the Sun. Although being designated "ε" (epsilon), it is the brightest star in the constellation. It has a magnitude of 1.77 which makes it the 33rd brightest star in the night sky.