Global InformationTheta1 Crucis information
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Crux |
| Right ascension | 12h 03m 01.50130s[1] |
| Declination | −63° 18′ 46.5406″[1] |
| Apparent magnitude (V) | 4.30[2] |
| Characteristics | |
| Spectral type | A3(m)A8-A8[3] |
| U−B color index | +0.03[2] |
| B−V color index | +0.28[2] |
| Astrometry | |
| Radial velocity (Rv) | −2.4[4] km/s |
| Proper motion (μ) | RA: −152.35[1] mas/yr Dec.: +7.00[1] mas/yr |
| Parallax (π) | 13.88 ± 0.15 mas[1] |
| Distance | 235 ± 3 ly (72.0 ± 0.8 pc) |
| Absolute magnitude (MV) | +1.29[5] |
| Orbit[6] | |
| Period (P) | 24.4828 d |
| Eccentricity (e) | 0.61 |
| Periastron epoch (T) | 2419453.3470 JD |
| Argument of periastron (ω) (secondary) | 358.9° |
| Semi-amplitude (K1) (primary) | 46.1 km/s |
| Semi-amplitude (K2) (secondary) | 56.1 km/s |
| Details | |
| Mass | 1.57[7] M☉ |
| Luminosity | 81[8] L☉ |
| Surface gravity (log g) | 3.76[7] cgs |
| Temperature | 7341±250[7] K |
| Age | 1.1[7] Gyr |
| Other designations | |
θ1 Cru, CPD−62° 2543, HD 104671, HIP 58758, HR 4599, SAO 251705.[9] | |
| Database references | |
| SIMBAD | data |
Theta1 Crucis (θ1 Cru, Theta1 Crucis) is a spectroscopic binary star system in the southern constellation of Crux. It is visible to the naked eye with an apparent visual magnitude of 4.30m.[2] The distance to this star, as determined using parallax measurements,[1] is around 235 light years.
The pair orbit each other closely with a period of 24.5 days and an eccentricity of 0.61.[6] The primary component is an Am star, which is a chemically peculiar A-type star that shows anomalous variations in absorption lines of certain elements.[10] It has a stellar classification of A3(m)A8-A8.[3] With a mass 157% times that of the Sun,[7] it radiates 81[8] times the Sun's luminosity from its outer atmosphere at an effective temperature of 7341 K.[7] Unusually for a fully radiative A-type star, X-ray emissions have been detected, which may instead be coming from the orbiting companion.[11]
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