Theta Chamaeleontis
Star in the constellation Chamaeleon
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Theta Chamaeleontis is a single,[8] orange-hued star located in the southern constellation of Chamaeleon. Its name is a Bayer designation that is Latinized from θ Chamaeleontis, and abbreviated Theta Cha or θ Cha. This is a dim star but visible to the naked eye with an apparent magnitude of 4.34.[3] Parallax measurements put the star at a distance of 152.8 light-years (46.8 pc).[2] It is moving away from the Sun with a radial velocity of +22 km/s.[6]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Chamaeleon[1] |
| Right ascension | 08h 20m 38.539s[2] |
| Declination | −77° 29′ 04.125″[2] |
| Apparent magnitude (V) | 4.34[3] |
| Characteristics | |
| Spectral type | K2 IIIb CN0.5[4] |
| U−B color index | +1.19[5] |
| B−V color index | +1.16[5] |
| Astrometry | |
| Radial velocity (Rv) | +21.70±0.7[6] km/s |
| Proper motion (μ) | RA: −129.048 mas/yr[2] Dec.: +40.598 mas/yr[2] |
| Parallax (π) | 21.3462±0.1010 mas[2] |
| Distance | 152.8 ± 0.7 ly (46.8 ± 0.2 pc) |
| Absolute magnitude (MV) | +0.97±0.10[3] |
| Details[3] | |
| Mass | 0.94±0.27 M☉ |
| Radius | 11.5 R☉ |
| Luminosity | 60[1] 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[7] | |
| Database references | |
| SIMBAD | data |
Theta Chamaeleontis is an evolved K-type giant star with a stellar classification of K2 IIIb CN0.5,[4] 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.[3] The star is radiating 60[1] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,570 K.[3]
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.[9]