Theta Cancri

Theta Cancri, is a multiple star^[8][4] system in the zodiac constellation of Cancer. Its name is a Bayer designation that is Latinised from θ Cancri, and abbreviated Theta Cnc or θ Cnc. This star is visible to the naked eye as a dim point of light with an apparent visual magnitude of +5.32.^[3] The system is located at a distance of approximately 432 light-years (132 pc) from the Sun, based on parallax,^[2] and is drifting further away with a radial velocity of +44 km/s.^[5] Since it is near the ecliptic, it can be occulted by the Moon^[9] and, very rarely, by planets.

Theta Cancri

Location of θ Cancri (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Cancer[1]
Right ascension	08h 31m 35.730s[2]
Declination	+18° 05′ 39.91″[2]
Apparent magnitude (V)	+5.323[3]
Characteristics
Spectral type	K5 III[4]
U−B color index	+1.949[3]
B−V color index	+1.565[3]
Astrometry
Radial velocity (Rv)	+44.47±0.19[5] km/s
Proper motion (μ)	RA: −59.639 mas/yr[2] Dec.: −56.615 mas/yr[2]
Parallax (π)	7.5577±0.1008 mas[2]
Distance	432 ± 6 ly (132 ± 2 pc)
Absolute magnitude (MV)	−0.19[1]
Details
Radius	40.02+2.22 −2.35[6] R☉
Luminosity	353.1±10.1[6] L☉
Surface gravity (log g)	4.41+0.79 −0.24[2] cgs
Temperature	4,600+4 −11[2] K
Other designations
θ Cnc, 31 Cancri, BD+18°1963, FK5 2667, HD 72094, HIP 41822, HR 3357, SAO 97881[7]
Database references
SIMBAD	data

The primary, designated component A, is K-type giant star with a stellar classification of K5 III,^[4] having exhausted the supply of hydrogen at its core, then cooled and expanded. At present it has 40^[6] times the girth of the Sun. It is radiating 353^[6] times the luminosity of the Sun at an effective temperature of 4,600 K.^[2]

In Chinese astronomy, Ghost (Chinese: 鬼宿; pinyin: Guǐ Xiù) refers to an asterism consisting of Theta Cancri, Eta Cancri, Gamma Cancri and Delta Cancri.^[10] Theta Cancri is the first star of Ghost (Chinese: 鬼宿一; pinyin: Guǐ Xiù yī), as it is also the determinative star for that asterism.^[11]