Gamma Cancri
Star system in the constellation Cancer
From Wikipedia, the free encyclopedia
Gamma Cancri is a star in the northern constellation of Cancer. Its name is a Bayer designation that is Latinized from γ Cancri, and abbreviated Gamma Cnc or γ Cnc. This star is formally named Asellus Borealis, pronounced /əˈsɛləs bɒriˈælɪs/, the traditional name of the system.[12] Based on parallax measurements, it is located at a distance of approximately 175 light-years (54 pc) from the Sun. The star is drifting further away with a radial velocity of 29 km/s.[6]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Cancer[1] |
| Right ascension | 08h 43m 17.147s[2] |
| Declination | +21° 28′ 06.60″[2] |
| Apparent magnitude (V) | 4.673[1] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | A1IV[4] |
| U−B color index | +0.03[5] |
| B−V color index | +0.010[1] |
| Astrometry | |
| Radial velocity (Rv) | 28.7[6] km/s |
| Proper motion (μ) | RA: −105.760 mas/yr[2] Dec.: −39.157 mas/yr[2] |
| Parallax (π) | 18.6431±0.1900 mas[2] |
| Distance | 175 ± 2 ly (53.6 ± 0.5 pc) |
| Absolute magnitude (MV) | +1.1[7] |
| Details | |
| Mass | 2.35±0.42[8] M☉ |
| Radius | 2.53±0.23[8] R☉ |
| Luminosity | 43.3±7.9[8] L☉ |
| Surface gravity (log g) | 4.00±0.25[8] cgs |
| Temperature | 9,311[8] K |
| Rotational velocity (v sin i) | 86±6[9] km/s |
| Age | 171[10] Myr |
| Other designations | |
| Asellus Borealis, γ Cnc, Gamma Cnc, 43 Cnc, BD+21°1895, FK5 1228, GC 11982, HD 74198, HIP 42806, HR 3449, SAO 80378, CCDM 08433+2128[11] | |
| Database references | |
| SIMBAD | data |
In 1910 this star was reported to be a spectroscopic binary by O. J. Lee,[13] but is now considered a single star.[14][15] Since it is near the ecliptic, it can be occulted by the Moon.[16]
Nomenclature
γ Cancri (Latinised to Gamma Cancri) is the star's Bayer designation. It bore the traditional name Asellus Borealis (Latin for "northern donkey").[17] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[18] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[19] It approved the name Asellus Borealis for the star on 6 November 2016 and it is now so included in the List of IAU-approved Star Names.[12] Together with Delta Cancri, it formed the Aselli, flanking Praesepe.[20]
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.[21] Gamma Cancri itself is known as the third star of Ghost (Chinese: 鬼宿三; pinyin: Guǐ Xiù sān).[22]
Properties
Gamma Cancri presents as a white A-type subgiant with an apparent magnitude of +4.67.[4] The star is an estimated 171[10] million years old and is spinning with a projected rotational velocity of 86 km/s.[9] It has 2.35 times the mass of the Sun, 2.53 times the Sun's radius, and shines with a luminosity approximately 43 times greater at an effective temperature of 9,311 K.[8]
It has been included as a member of the Hyades Stream based on its distance, space motion, and estimated age.[23]