Theta Chamaeleontis

Theta Chamaeleontis, Latinized from θ Cha, is a single,^[7] 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.^[2] Parallax measurements by the Hipparcos spacecraft put the system at 155 light-years, or 47.6 parsecs away.^[1] It is moving away from the Sun with a radial velocity of +22 km/s.^[5]

θ Chamaeleontis

Observation data Epoch J2000      Equinox J2000
Constellation	Chamaeleon
Right ascension	08h 20m 38.54055s[1]
Declination	−77° 29′ 04.1173″[1]
Apparent magnitude (V)	4.34[2]
Characteristics
Spectral type	K2 IIIb CN0.5[3]
U−B color index	+1.19[4]
B−V color index	+1.16[4]
Astrometry
Radial velocity (Rv)	+21.70±0.7[5] km/s
Proper motion (μ)	RA: −129.05[1] mas/yr Dec.: +40.89[1] mas/yr
Parallax (π)	21.00±0.14 mas[1]
Distance	155 ± 1 ly (47.6 ± 0.3 pc)
Absolute magnitude (MV)	+0.97±0.10[2]
Details[2]
Mass	0.94±0.27 M☉
Radius	11.5 R☉
Luminosity	60[6] 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 is an evolved K-type giant star with a stellar classification of K2 IIIb CN0.5,^[3] 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.^[2] The star is radiating 60^[6] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,570 K.^[2]

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.^[8]