Zeta Capricorni
 Location of ζ Capricorni (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Capricornus |
| Right ascension | 21h 26m 40.02634s |
| Declination | −22° 24′ 40.8042″ |
| Apparent magnitude (V) | 3.74 |
| Characteristics | |
| Spectral type | G8IIIp / DA2.2 |
| U−B color index | +0.57 |
| B−V color index | +0.99 |
| Astrometry | |
| Radial velocity (Rv) | 2.10 km/s |
| Proper motion (μ) |
RA: -2.23 mas/yr Dec.: 18.10 mas/yr |
| Parallax (π) | 8.46 ± 0.21mas |
| Distance | 386 ± 10 ly (118 ± 3 pc) |
| Absolute magnitude (MV) | 0.88 |
| Orbit | |
| Primary | ζ Cap A |
| Companion | ζ Cap B |
| Period (P) | 2378.2 d |
| Semi-major axis (a) | 8.56 ± 4.3 mas |
| Eccentricity (e) | 0.2821 |
| Inclination (i) | 111.7 ± 20.7° |
| Longitude of the node (Ω) | 190.7 ± 50.0° |
| Periastron epoch (T) | JD 2445996 |
|
Argument of periastron (ω) (secondary) |
233.8 ± 19.8° |
| Details | |
| ζ Cap A | |
| Mass | 3.99 ± 0.12 M☉ |
| Radius | ~29 R☉ |
| Luminosity | 490 L☉ |
| Surface gravity (log g) | 1.48 ± 0.16 cgs |
| Temperature | 5397 ± 82 K |
| Metallicity [Fe/H] | −0.14 ± 0.10 dex |
| ζ Cap B | |
| Mass | 1 M☉ |
| Temperature | 23000 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
Zeta Capricorni, (ζ Cap, ζ Capricorni), is a fourth-magnitude star in the constellation Capricornus. ζ Capricorni is a binary star, with the primary component ζ Capricorni A being a yellow G-type giant with an apparent magnitude of +3.77. It is considered one of the prototypical examples of a Barium star, properties of which include overabundances of carbon molecules (such as C2) and s-process elements. Zeta Capricorni has an overabundance of the s-process element praseodymium.
Its companion, ζ Capricorni B is a hydrogen-rich white dwarf. It is about as massive as the Sun, and its temperature is 23,000 K.
The ζ Capricorni binary system is approximately 390 light years from Earth, based on its parallax.
In Chinese, 十二國 (Shíer Guó), meaning Twelve States, refers to an asterism which represents twelve ancient states in the Spring and Autumn period and the Warring States period, consisting of ζ Capricorni, φ Capricorni, ι Capricorni, 38 Capricorni, 35 Capricorni, 36 Capricorni, χ Capricorni, θ Capricorni, 30 Capricorni, 33 Capricorni, 19 Capricorni, 26 Capricorni, 27 Capricorni, 20 Capricorni, η Capricorni and 21 Capricorni. Consequently, ζ Capricorni itself represents the state of Yan (燕)., together with ν Ophiuchi in Left Wall of Heavenly Market Enclosure (asterism).
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