Theta2 Crucis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Crux |
| Right ascension | 12h 04m 19.22008s |
| Declination | −63° 09′ 56.5167″ |
| Apparent magnitude (V) | 4.70 - 4.74 |
| Characteristics | |
| Spectral type | B3 V |
| U−B color index | −0.61 |
| B−V color index | −0.08 |
| Variable type | β Cep |
| Astrometry | |
| Radial velocity (Rv) | +16.3 km/s |
| Proper motion (μ) | RA: −18.467 mas/yr Dec.: +0.467 mas/yr |
| Parallax (π) | 4.7314±0.1276 mas |
| Distance | 690 ± 20 ly (211 ± 6 pc) |
| Absolute magnitude (MV) | −2.35 |
| Orbit | |
| Period (P) | 3.428 d |
| Eccentricity (e) | 0.00 |
| Periastron epoch (T) | 2419604.367 JD |
| Semi-amplitude (K1) (primary) | 51.3 km/s |
| Details | |
| Mass | 5.9 M☉ |
| Radius | 6.9 R☉ |
| Luminosity | 1,935 L☉ |
| Surface gravity (log g) | 3.55 cgs |
| Temperature | 15,361 K |
| Metallicity [Fe/H] | +0.20 dex |
| Rotational velocity (v sin i) | 23 km/s |
| Age | 18.5 Myr |
| Other designations | |
| θ2 Cru, CD−62°610, HD 104841, HIP 58867, HR 4603, SAO 251717 | |
| Database references | |
| SIMBAD | data |
Theta2 Crucis, Latinized from θ2 Crucis, is a spectroscopic binary star in the constellation Crux. This pair of stars complete an orbit every 3.4280 days and they have a low orbital eccentricity that is close to 0.0. Theta2 Crucis is located at about 690 light-years from the Sun.
Since a member of the system is a β Cephei-type variable star, the magnitude is not fixed but varies slightly between +4.70 and +4.74. The period of this variability is 0.0889 days. The system is categorized as is a blue-white B-type main sequence star with a stellar classification of B3 V, although it has also been classified as a subgiant. Evolutionary models show it at a late stage of its main sequence life.