Theta Capricorni
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 21h 05m 56.82783s |
| Declination | −17° 13′ 58.3021″ |
| Apparent magnitude (V) | +4.07 |
| Characteristics | |
| Spectral type | A1 V |
| U−B color index | +0.01 |
| B−V color index | −0.01 |
| Astrometry | |
| Radial velocity (Rv) | −10.9 km/s |
| Proper motion (μ) | RA: +79.33 mas/yr Dec.: −62.01 mas/yr |
| Parallax (π) | 20.11±0.28 mas |
| Distance | 162 ± 2 ly (49.7 ± 0.7 pc) |
| Absolute magnitude (MV) | +0.60 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 143 days |
| Semi-major axis (a) | 0.78 AU |
| Details | |
| A | |
| Mass | 2.54 M☉ |
| Radius | 2.35 R☉ |
| Luminosity | 65 L☉ |
| Surface gravity (log g) | 4.19±0.14 cgs |
| Temperature | 10,221 K |
| Metallicity [Fe/H] | +0.26 dex |
| Rotational velocity (v sin i) | 104 km/s |
| Age | 280 Myr |
| B | |
| Mass | 0.56 M☉ |
| Radius | 0.52 R☉ |
| Temperature | 3,900 K |
| Age | 280 Myr |
| Other designations | |
| θ Cap, 23 Cap, BD−17°6174, FK5 1552, HD 200761, HIP 104139, HR 8075, SAO 164132 | |
| Database references | |
| SIMBAD | data |
Theta Capricorni, Latinized from θ Capricorni, is a binary star in the southern constellation of Capricornus, positioned 0.58° south of the ecliptic. Sometimes, this star is called by the name Dorsum, meaning the back (of the goat) in Latin. It can be seen with the naked eye, having an apparent visual magnitude of +4.07. Based upon an annual parallax shift of 20.11 mas as seen from the Earth, the star is about 162 light years from the Sun. It is drifting closer with a radial velocity of −11 km/s.