Alpha Cassiopeiae: Difference between revisions
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Revision as of 01:32, 21 February 2007
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 00h 40m 30.5s |
| Declination | +56° 32′ 14.5″ |
| Apparent magnitude (V) | 2.24 |
| Characteristics | |
| Spectral type | K0 IIIa |
| U−B color index | 1.13 |
| B−V color index | 1.17 |
| Variable type | Suspected |
| Astrometry | |
| Radial velocity (Rv) | −3.8 km/s |
| Proper motion (μ) | RA: 50.36 mas/yr Dec.: −32.17 mas/yr |
| Parallax (π) | 14.27 ± 0.57 mas |
| Distance | 229 ± 9 ly (70 ± 3 pc) |
| Absolute magnitude (MV) | −1.99 |
| Details | |
| Mass | 4–5 M☉ |
| Radius | 42 R☉ |
| Luminosity | 855 L☉ |
| Temperature | 4,530 K |
| Metallicity | ? |
| Rotation | 21 km/s |
| Age | ? years |
| Other designations | |
Alpha Cassiopeiae (α Cas / α Cassiopeiae ) is the second-brightest star in the constellation Cassiopeia (magnitude 2.25). It has the traditional name Schedar (which may also be spelt as Shedar, Shadar, Schedir, or Shedir).
It is an orange giant (spectral type K0 IIIa), a type of star cooler but much brighter than our Sun. In visible light only, it is well over 500 times brighter than the Sun. According to the Hipparcos astrometrical satellite, distance to the star is about 230 light years (or 70 parsecs).
Schedar has been sometimes classified as a variable star, but no variability has been detected since the 19th century. Also, three companions to the star have been listed in the Washington Double Star Catalog, but it seems that all of them are just line-of-sight optical components.
The name Schedar comes from the Arabic word صدر şadr, "breast".
External link
- Shedar at Jim Kaler's Stars site
- Shedar (Alpha Cassiopeiae)
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