Zeta Cassiopeiae
 ζ Cas is found just south of α Cas |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 00h 36m 58.28419s[1] |
| Declination | +53° 53′ 48.8673″[1] |
| Apparent magnitude (V) | 3.66[2] (3.59 - 3.68[3]) |
| Characteristics | |
| Spectral type | B2IV[4] |
| U−B color index | –0.89[5] |
| B−V color index | –0.19[5] |
| Variable type | SPB[3] |
| Astrometry | |
| Radial velocity (Rv) | 2.0[3] km/s |
| Proper motion (μ) | RA: 17.38[1] mas/yr Dec.: –9.86[1] mas/yr |
| Parallax (π) | 5.50 ± 0.16[1] mas |
| Distance | 590 ± 20 ly (182 ± 5 pc) |
| Absolute magnitude (MV) | –2.8[6] |
| Details | |
| Mass | 8.3[3] M☉ |
| Radius | 5.9[3] R☉ |
| Luminosity | 5,500[3] L☉ |
| Surface gravity (log g) | 3.81[3] cgs |
| Temperature | 20,426[3] K |
| Metallicity [Fe/H] | –0.23[7] dex |
| Rotation | 5.37045[3] |
| Rotational velocity (v sin i) | 17 ± 3[3] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Zeta Cassiopeiae (ζ Cas, ζ Cassiopeiae) is a star in the constellation Cassiopeia. It has a blue-white hue and is classified as a B-type subgiant with an apparent magnitude of +3.66. It is approximately 590 light years from Earth.
ζ Cas is a probable member of an unusual group of variable stars known as "Slowly Pulsating B" (SPB) stars.[9] It shows a pulsation frequency of 0.64 per day (or once every 1.56 days) and displays a weak magnetic field with a strength of roughly 3.35 × 10−2 T, which varies with a period of 5.37 days.[10] This likely matches the rotation rate of the star, which, when combined with the low projected rotational velocity, indicates the star may be seen nearly pole-on. Zeta Cassiopeiae is a candidate magnetic Bp star that shows an overabundance of helium. The star contains a randomly oriented fossil magnetic field, which impacts the outflow of the stellar wind. Collisions between streams from this stellar wind creates a shock front, with cooling particles settling toward a co-rotating disk.[11]
Chinese name
In Chinese astronomy, Zeta Cassiopeiae is called 附路, Pinyin: Fùlù, meaning Auxiliary Road, because this star is marking itself and stand alone in Auxiliary Road asterism, Legs (mansion) (see : Chinese constellation).[12] 附路 (Fùlù) is westernized into Foo Loo, but the name Foo Loo was designated not only for Zeta Cassiopeiae, but also for η Cassiopeiae (Achird) by R.H. Allen, with the meaning is "a by-path" [13]
See also
- Lists of stars in the constellation Cassiopeiae
- Class B Stars
- Pulsating Variable Stars
References
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- ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 9 日
- ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Cassiopeia
