Eta Cassiopeiae
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| Observation data Epoch J2000 |
|
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 00h 49m 06.3s |
| Declination | +57° 48' 54" |
| Apparent magnitude (V) | 3.46/7.51 |
| Characteristics | |
| Spectral type | G3V/K7V |
| B-V color index | 0.57/1.39 |
| U-B color index | 0.02/1.03 |
| Variable type | RS CVn |
| Astrometry | |
| Radial velocity (Rv) | +8.5 km/s |
| Proper motion (μ) | RA: 1087.11 mas/yr Dec.: -0559.65 mas/yr |
| Parallax (π) | 168.38 ± 0.59 mas |
| Distance | 19.37 ± 0.07 ly (5.94 ± 0.02 pc) |
| Absolute magnitude (MV) | 4.59/8.64 |
| Visual binary orbit | |
| Companion | Gl 34B |
| Period (P) | 480 years |
| Semimajor axis (a) | 11.99" |
| Eccentricity (e) | 0.497 |
| Inclination (i) | 34.76° |
| Node (Ω) | 98.42° |
| Periastron epoch (T) | 88.59 |
| Details | |
| Mass | 0.91/0.56 M☉ |
| Radius | 1,17/0.40 R☉ |
| Luminosity | 1.20/0.03 L☉ |
| Temperature | 5600/3800 K |
| Metallicity | 63-68% |
| Rotation | ? |
| Age | ? years |
| Other designations | |
Eta Cassiopeiae (η Cas / η Cassiopeiae) is a star system 19.4 light years away from Earth, in the constellation Cassiopeia. Sometimes the traditional name Achird is used. It is known as 王良三 (the Third Star of Wang Liang) in Chinese.
The primary star in the η Cassiopeiae system is a yellow dwarf (main sequence) star of spectral type G3V, putting it in the same spectral class as our Sun, which is of spectral type G2V. It therefore resembles what our Sun might look like if we were to observe it from η Cassiopeiae. The star is of apparent magnitude 3.45. The star has a cooler and dimmer (magnitude 7.51) orange dwarf companion of spectral type K7V. The system is an RS Canum Venaticorum type variable star and its brightness varies by 0.05 magnitudes.
There are six dimmer optical components listed in the Washington Double Star Catalog. However, none of them are related to the η Cassiopeiae system and are in reality more distant stars.
[edit] See also
[edit] External links
- Eta Cassiopeiae 2. SolStation. Retrieved on November 3, 2005.
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