Gamma Ursae Minoris
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| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation (pronunciation) |
Ursa Minor |
| Right ascension | 15h 20m 43.7155s |
| Declination | +71° 50' 02.458" |
| Apparent magnitude (V) | +3.027 |
| Characteristics | |
| Spectral type | A3Iab: |
| U-B color index | +0.12 |
| B-V color index | +0.05 |
| Astrometry | |
| Radial velocity (Rv) | -3.9 km/s |
| Proper motion (μ) | RA: -18.03 mas/yr Dec.: 17.68 mas/yr |
| Parallax (π) | 6.79 ± 0.46 mas |
| Distance | 480 ± 30 ly (147 ± 10 pc) |
| Other designations | |
Gamma Ursae Minoris (γ UMi / γ Ursae Minoris) is a slightly variable star in the constellation Ursa Minor. It also has the common name Pherkad. Together with Beta Ursae Minoris, Gamma forms the end of the dipper pan of the "Little Dipper". The name "Pherkad" derives from the Arabic for "the two calves," which originally referred to both Kochab and Pherkad. Together, they are also called the "Guardians of the Pole."[2]
Gamma Ursae Minoris has apparent magnitude +3.00. It is approximately 480 light years from Earth and is of spectral class A3, meaning it has a surface temperature of 7,500 to 11,000 kelvins. It is classified as a Delta Scuti type variable star and its brightness varies by 0.05 magnitudes with a period of 3.43 hours. It is 1100 times more luminous than the Sun, and possesses a radius 15 times that of the Sun.[2]
[edit] References
- ^ Simbad Query Result. Simbad. Retrieved on October 5, 2007.
- ^ a b Pherkad. Simbad. Retrieved on October 5, 2007.
| Preceded by Thuban |
Pole Star 1900 BC–500 |
Succeeded by Polaris |
