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Al Tarf is the bottom right star in the "crab" |
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| Observation data Epoch J2000 Equinox J2000 |
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|---|---|
| Constellation | Cancer |
| Right ascension | 08h 16m 30.9206s[1] |
| Declination | +09° 11′ 07.961″[1] |
| Apparent magnitude (V) | 3.536 [1] |
| Characteristics | |
| Spectral type | K4III [1] |
| U−B color index | -1.77 [1] |
| B−V color index | -1.48 [1] |
| Variable type | ? |
| Astrometry | |
| Radial velocity (Rv) | 22.94 [1] km/s |
| Proper motion (μ) | RA: -46.80 [1] mas/yr Dec.: −48.65 [1] mas/yr |
| Parallax (π) | 11.23 ± 0.97[1] mas |
| Distance | 290 ± 30 ly (89 ± 8 pc) |
| Absolute magnitude (MV) | -1.21 |
| Details | |
| Mass | ? M☉ |
| Radius | 53 [2] R☉ |
| Surface gravity (log g) | 1.51 [3] |
| Luminosity | 660 [2] L☉ |
| Temperature | 4,039 [3] K |
| Metallicity | -0.12[3]. |
| Rotation | 8 km/s.[1] |
| Other designations | |
| Database references | |
| SIMBAD | data |
Beta Cancri (β Cnc, β Cancri) is the brightest star in the constellation Cancer. It has the traditional name Tarf or Al Tarf (Altarf), certainly a derivation from Arabic الطرف aṭ-ṭarf "the eye" or طرفة aṭ-ṭarfah "the glance (of Leo)". It is approximately 290 light years from Earth.
The primary component, β Cancri A, is an orange K-type giant with an apparent magnitude of +3.50 and absolute magnitude of -1.25 (visual). It has a faint, fourteenth magnitude companion, β Cancri B, located 29 arcseconds from the primary.
Jim Kaler's Stars: Al Tarf
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