Back المغرز (نجم) Arabic Megrez AST Megrez Catalan Megrez Czech Megrez German Megrez Spanish مغرز Persian Delta Ursae Majoris Finnish Delta Ursae Majoris French Megrez FUR
  Location of Megrez (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 12h 15m 25.56063s[1] |
| Declination | +57° 01′ 57.4156″[1] |
| Apparent magnitude (V) | +3.312[2] |
| Characteristics | |
| Spectral type | A3 V[3] |
| U−B color index | +0.067[2] |
| B−V color index | +0.075[2] |
| Astrometry | |
| Radial velocity (Rv) | -20.2[4] km/s |
| Proper motion (μ) | RA: +104.11[1] mas/yr Dec.: 7.30[1] mas/yr |
| Parallax (π) | 40.51 ± 0.15 mas[1] |
| Distance | 80.5 ± 0.3 ly (24.69 ± 0.09 pc) |
| Absolute magnitude (MV) | +1.39[5] |
| Details[6] | |
| 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[7] cgs |
| Temperature | 6,909 (equatorial) 10,030 (polar) K |
| Rotation | 3.1[6][a] hours |
| Rotational velocity (v sin i) | 244.6+11.6 −11.1 km/s |
| Age | 414+35 −43 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Megrez /ˈmiːɡrɛz/, also called Delta Ursae Majoris (δ Ursae Majoris, abbreviated Delta UMa, δ UMa),[9][10] is a star in the northern constellation of Ursa Major. With an apparent magnitude of +3.3,[2] 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.[1]
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SIMBADwas invoked but never defined (see the help page). - ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
- ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
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