Phi Ursae Majoris, a white subgiant star in Ursa Major
Phi Ursae Majoris is a white subgiant star in the constellation Ursa Major. At 509 light years away, it shines at an apparent visual magnitude of 4.56.
Phi Ursae Majoris (HIP 48402)
Phi Ursae Majoris is a white subgiant star in the constellation Ursa Major. At 509 light years away, it shines at an apparent visual magnitude of 4.56. It is moving through the Galaxy at a speed of 20.9 km/s relative to the Sun.
Sky position: RA 9h 52.1m, Dec +54° 3.9'
Common designations: Phi Ursae Majoris, 30 Ursae Majoris, HR 3894, HD 85235, HIP 48402
Phi Ursae Majoris has the spectral type A3IV. A-type stars are white stars with surface temperatures of roughly 7,500 to 10,000 K. Their spectra are dominated by strong hydrogen lines, and many of them rotate rapidly. Its luminosity class IV marks it as a subgiant: it has exhausted hydrogen in its core and is beginning to expand toward the giant phase.
How to find Phi Ursae Majoris in the sky
Phi Ursae Majoris lies in Ursa Major. With a declination of +54° 3.9', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 36° S. Observers poleward of latitude 36° N see it as circumpolar: it never sets. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around March, which makes the weeks around that month the best time to observe it.
Tabulated data for Phi Ursae Majoris
Astrometry and spectroscopy
| Right Ascension (J2000) | 148.02647655° (9h 52.1m) |
| Declination (J2000) | 54.06433229° (+54° 3.9') |
| Galactic Longitude | 160.86797595° |
| Galactic Latitude | 47.69781229° |
| Proper motion RA | -6.00 mas/yr |
| Proper motion Dec | 19.16 mas/yr |
| Parallax | 6.41 ± 0.59 mas |
| Spectral Type | A3IV |
| Radial Velocity | -14.70 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| B | 4.60 | -1.36 |
| V | 4.56 | -1.41 |
| J | 4.70 | -1.27 |
| H | 4.57 | -1.40 |
| K | 4.38 | -1.59 |
Colour index B-V: +0.04
Derivations
- Heliocentric distance: 156.01 pc (509 light years) (9.2% margin of error)
- Absolute visual magnitude: -1.41
- Transverse velocity: 14.8 km/s
- Space velocity relative to the Sun: 20.9 km/s
- Galactic position (X, Y, Z): -99.2 pc, 34.4 pc, 115.4 pc
- Galactic velocity (U, V, W): 6.7 km/s, 10.0 km/s, -17.1 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.