Megrez

Megrez

Location of Megrez (circled)
Observation data Epoch J2000      Equinox ICRS
Constellation	Ursa Major
Right ascension	12h 15m 25.56063s
Declination	+57° 01′ 57.4156″
Apparent magnitude (V)	+3.312
Characteristics
Evolutionary stage	main sequence
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
Rotational velocity (v sin i)	244.6+11.6 −11.1 km/s
Age	414+35 −43 Myr
Other designations
Megrez, δ UMa, 69 UMa, BD+57 1363, FK5 456, GC 16736, GJ 459, HD 106591, HIP 59774, HR 4660, SAO 28315, PPM 33469, CCDM J12155+5702A, WDS J12154+5702A, IDS 12105+5735 A
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.