ζ Cas is found just below α Cas |
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Observation data Epoch J2000 Equinox J2000 |
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Constellation | Cassiopeia |
Right ascension | 00h 36m 58.28419s[1] |
Declination | +53° 53′ 48.8673″[1] |
Apparent magnitude (V) | 3.666[2] |
Characteristics | |
Spectral type | B2IV[3] |
U−B color index | –0.89[4] |
B−V color index | –0.19[4] |
Variable type | SPB[5] |
Astrometry | |
Radial velocity (Rv) | 2.0[2] 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) | –2.63 |
Details | |
Mass | 8.4[6] M☉ |
Radius | 6.1[5] R☉ |
Surface gravity (log g) | 3.92[7] |
Luminosity | 6,400[5] L☉ |
Temperature | 22,180[7] K |
Metallicity [Fe/H] | –0.23[7] dex |
Rotational velocity (v sin i) | 2.0[8] km/s |
Age | 2.0×107[5] years |
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 +3.67. It is approximately 590 light years from Earth.[1]
ζ Cas is a member of an unusual group of variable stars known as "Slowing 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]
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]
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