Theta Chamaeleontis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Chamaeleon |
| Right ascension | 08h 20m 38.54055s |
| Declination | −77° 29′ 04.1173″ |
| Apparent magnitude (V) | 4.34 |
| Characteristics | |
| Spectral type | K2 IIIb CN0.5 |
| U−B color index | +1.19 |
| B−V color index | +1.16 |
| Astrometry | |
| Radial velocity (Rv) | +21.70±0.7 km/s |
| Proper motion (μ) | RA: −129.05 mas/yr Dec.: +40.89 mas/yr |
| Parallax (π) | 21.00±0.14 mas |
| Distance | 155 ± 1 ly (47.6 ± 0.3 pc) |
| Absolute magnitude (MV) | +0.97±0.10 |
| Details | |
| Mass | 0.94±0.27 M☉ |
| Radius | 11.5 R☉ |
| Luminosity | 60 L☉ |
| Surface gravity (log g) | 2.29±0.29 cgs |
| Temperature | 4,570 K |
| Other designations | |
| θ Cha, CPD−77°383, FK5 318, HD 71701, HIP 40888, HR 3340, SAO 256503 | |
| Database references | |
| SIMBAD | data |
Theta Chamaeleontis, Latinized from θ Cha, is a single, orange-hued star located in the southern constellation of Chamaeleon. It is a dim star but visible to the naked eye with an apparent magnitude of 4.34. Parallax measurements by the Hipparcos spacecraft put the system at 155 light-years, or 47.6 parsecs away. It is moving away from the Sun with a radial velocity of +22 km/s.
Theta Chamaeleontis is an evolved K-type giant star with a stellar classification of K2 IIIb CN0.5, where the suffix notation indicates the outer atmosphere has a mild overabundance of cyanogen. It has 0.94 times the mass of the Sun, and has expanded to 11.5 times as wide. The star is radiating 60 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,570 K.
It has a visual companion, Theta Chamaeleontis B. This is a magnitude 12.44 star at an angular separation of 21.1 arcseconds from component A along a position angle of 237°, as of 2000.