  | |
| Observation data EpochJ2000.0 EquinoxJ2000.0 (ICRS) | |
|---|---|
| Constellation | Cancer[1] |
| Right ascension | 08h 31m 35.730s[2] |
| Declination | +18° 05′ 39.91″[2] |
| Apparent magnitude (V) | +5.323[3] |
| Characteristics | |
| Evolutionary stage | red giant branch[2] |
| Spectral type | K5 III[4] |
| U−Bcolor index | +1.949[3] |
| B−Vcolor index | +1.565[3] |
| Astrometry | |
| Radial velocity (Rv) | +44.47±0.19[5] km/s |
| Proper motion (μ) | RA: −59.639mas/yr[2] Dec.: −56.615mas/yr[2] |
| Parallax (π) | 7.5577±0.1008 mas[2] |
| Distance | 432 ± 6 ly (132 ± 2 pc) |
| Absolute magnitude (MV) | −0.19[1] |
| Details | |
| Mass | 1.3[6] M☉ |
| Radius | 67[2] R☉ |
| Luminosity | 949[2] L☉ |
| Surface gravity (log g) | 1.82[6] cgs |
| Temperature | 3,998[6] K |
| Metallicity[Fe/H] | −0.19[6] dex |
| Other designations | |
| θ Cnc,31 Cancri,BD+18°1963,FK5 2667,HD 72094,HIP 41822,HR 3357,SAO 97881[7] | |
| Database references | |
| SIMBAD | data |
Theta Cancri, is amultiple star[8][4] system in thezodiacconstellation ofCancer. Its name is aBayer designation that isLatinised from θ Cancri, and abbreviated Theta Cnc or θ Cnc. This star is visible to thenaked eye as a dim point of light with anapparent visual magnitude of +5.32.[3] The system is located at a distance of approximately 432light-years (132 pc) from the Sun, based onparallax,[2] and is drifting further away with aradial velocity of +44 km/s.[5] Since it is near theecliptic, it can beocculted by theMoon[9] and, very rarely, byplanets.
The primary, designated component A, isK-typegiant star with astellar classification of K5 III,[4] having exhausted the supply of hydrogen at itscore, then cooled and expanded. At present it has 67 times the girth of the Sun. It is radiating 949[2] times theluminosity of the Sun at aneffective temperature of3,998 K.[6]
InChinese astronomy,Ghost (Chinese:鬼宿;pinyin:Guǐ Xiù) refers to anasterism consisting of Theta Cancri,Eta Cancri,Gamma Cancri andDelta 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]
