This Big Medvedev ( η UMa / η Ursae Majoris) is a star of the main sequence spectral class B3 in the constellation Ursa Major . She also has the traditional names Benetnash and Alkaid from the full Arabic name al-Qaid Banat ours , which means "leader of the mourners." It is the third brightest star in the constellation (the apparent magnitude of 1.85 m ) and the 35th in the list of the brightest stars in the sky. Benetnash is about 100 light-years from the Sun. With a surface temperature of 22,000 K, it is among the hottest stars that can be seen with the naked eye.
| This Big Dipper | |||
|---|---|---|---|
| Star | |||
| Observational data ( Epoch J2000.0 ) | |||
| Right ascension | |||
| Declination | |||
| Distance | 101 ± 2 over . year (30.9 ± 0.7 pc ) | ||
| Visible magnitude ( V ) | 1.85 [1] | ||
| Constellation | Big Dipper | ||
| Astrometry | |||
| Radial velocity ( R v ) | −11 km / s | ||
| Proper motion (μ) | RA: −121,23 mas per year Dec: 15.56 mas per year | ||
| Parallax (π) | 32.39 ± 0.74 mas | ||
| Absolute magnitude (V) | -0,6 | ||
| Specifications | |||
| Spectral class | B3V | ||
| Color Indicator ( B - V ) | −0.19 | ||
| Color Index ( U - B ) | −0.67 | ||
| physical characteristics | |||
| Weight | 6 M ☉ | ||
| Radius | 1.8 R ☉ | ||
| Temperature | 22,000 K | ||
| Luminosity | 700 L ☉ | ||
| Rotation | ~ 200 km / s | ||
| |||
| Information in databases | |||
| SIMBAD | data | ||
Located at the “end of the handle” of the asterism Big Dipper .
See also
- List of stars in the constellation Ursa Major
Notes
- ↑ Crawford, DL; Barnes, JV & Golson, JC (1971), " Four-color, H-beta, and B-type stars for the northern hemisphere ", The Astronomical Journal T. 76: 1058 , DOI 10.1086 / 111220
Links
- Alkaid in Jim Kaler's star website