Delta Cassiopeiae
 Ruchbach (circled) is the bottom left star in the "W" |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 01h 25m 48.95147s |
| Declination | +60° 14′ 07.0225″ |
| Apparent magnitude (V) | 2.68 |
| Characteristics | |
| Spectral type | A5III-IVv |
| U−B color index | +0.13 |
| B−V color index | +0.13 |
| Variable type | Eclipsing binary |
| Astrometry | |
| Radial velocity (Rv) | −6.7 km/s |
| Proper motion (μ) |
RA: 296.57 mas/yr Dec.: –49.22 mas/yr |
| Parallax (π) | 32.81 ± 0.14mas |
| Distance | 99.4 ± 0.4 ly (30.5 ± 0.1 pc) |
| Details | |
| Mass | 2.5 M☉ |
| Radius | 3.90 R☉ |
| Luminosity | 63 L☉ |
| Temperature | 8,400 K |
| Rotational velocity (v sin i) | 123 km/s |
| Age | 6.0×108 years |
| Other designations | |
| Database references | |
| SIMBAD | data |
Delta Cassiopeiae (δ Cassiopeiae, abbreviated Delta Cas, δ Cas), also named Ruchbah, is a star in the northern circumpolar constellation of Cassiopeia.
δ Cassiopeiae (Latinised to Delta Cassiopeiae) is the star's Bayer designation.
It also bore the traditional names Ruchbah and Ksora; the former deriving from the Arabic word ركبة rukbah meaning "knee", and the latter appeared in a 1951 publication, Atlas Coeli (Skalnate Pleso Atlas of the Heavens) by Czech astronomer Antonín Bečvář. Professor Paul Kunitzch has been unable to find any clues as to the origin of the name. The star Alpha Sagittarii also bore the traditional name Ruchbah (as well as Rukbat). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Ruchbah for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names (Alpha Sagittarii was given the name Rukbat).
In Chinese, 閣道 (Gé Dào), meaning Flying Corridor, refers to an asterism consisting of Delta Cassiopeiae, Iota Cassiopeiae, Epsilon Cassiopeiae, Theta Cassiopeiae, Nu Cassiopeiae and Omicron Cassiopeiae. Consequently, Delta Cassiopeiae itself is known as 閣道三 (Gé Dào sān, English: the Third Star of Flying Corridor.)
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