Megrez
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 12h 15m 25.56063s |
| Declination | +57° 01′ 57.4156″ |
| Apparent magnitude (V) | +3.312 |
| Characteristics | |
| Spectral type | A3 V |
| U−B color index | +0.067 |
| B−V color index | +0.075 |
| Astrometry | |
| Radial velocity (Rv) | -20.2 km/s |
| Proper motion (μ) | RA: +104.11 mas/yr Dec.: 7.30 mas/yr |
| Parallax (π) | 40.51±0.15 mas |
| Distance | 80.5 ± 0.3 ly (24.69 ± 0.09 pc) |
| Absolute magnitude (MV) | +1.39 |
| Details | |
| Mass | 2.062+0.020 −0.033 M☉ |
| Radius | 2.512 (equatorial) 1.921 (polar) R☉ |
| Luminosity | 23+1.24 −1.21 L☉ |
| Surface gravity (log g) | 4.49 cgs |
| Temperature | 6,909 (equatorial) 10,030 (polar) K |
| Rotation | 3.1 hours |
| Rotational velocity (v sin i) | 244.6+11.6 −11.1 km/s |
| Age | 414+35 −43 Myr |
| Other designations | |
| Megrez, δ Ursae Majoris, δ UMa, Delta UMa, 69 Ursae Majoris, BD+57 1363, CCDM J12155+5702A, FK5 456, GC 16736, HD 106591, HIP 59774, HR 4660, IDS 12105+5735 A, PPM 33469, SAO 28315, WDS J12154+5702A. | |
| Database references | |
| SIMBAD | data |
Megrez /ˈmiːɡrɛz/, also called Delta Ursae Majoris (δ Ursae Majoris, abbreviated Delta UMa, δ UMa), is a star in the northern constellation of Ursa Major. With an apparent magnitude of +3.3, it is the dimmest of the seven stars in the Big Dipper asterism. Parallax measurements yield a distance estimate of 80.5 light-years (24.7 parsecs) from the Sun.