66 Cancri
Binary star system in the constellation of Cancer
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66 Cancri is a binary star[9] system near the northern border of the zodiac constellation of Cancer, located 474 light years away from the Sun. It is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 5.87.[2] The pair are moving closer to the Earth with a heliocentric radial velocity of −13 light years.[6] As of 2003, the magnitude 8.56 companion was located at an angular separation of 4.43″ along a position angle of 134° from the primary.[9]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cancer |
| Right ascension | 09h 01m 24.13000s[1] |
| Declination | +32° 15′ 08.2666″[1] |
| Apparent magnitude (V) | 5.870[2] (5.95 + 8.56)[3] |
| Characteristics | |
| Evolutionary stage | main sequence[4] |
| Spectral type | A2 V[2] |
| B−V color index | 0.088±0.007[5] |
| Astrometry | |
| Radial velocity (Rv) | −12.8±2.9[6] km/s |
| Proper motion (μ) | RA: +0.48[7] mas/yr Dec.: +0.34[7] mas/yr |
| Parallax (π) | 6.8850±0.1020 mas[1] |
| Distance | 474 ± 7 ly (145 ± 2 pc) |
| Absolute magnitude (MV) | 0.14[5] |
| Details | |
| Mass | 2.73±0.11[4] M☉ |
| Luminosity | 95.7+24.6 −19.5[4] L☉ |
| Surface gravity (log g) | 4.0[2][4] cgs |
| Temperature | 8,974+230 −224[4] K |
| Rotational velocity (v sin i) | 183[4] km/s |
| Age | 162[2] Myr |
| Other designations | |
| 66 Cnc, BD+32°1829, HD 77104, HIP 44307, HR 3587, SAO 61202, WDS 09014+3215[8] | |
| Database references | |
| SIMBAD | data |
The brighter member of the system, designated component A, is an A-type main-sequence star with a stellar classification of A2 V.[2] It is around 162[2] million years old with a high rate of spin, showing a projected rotational velocity of 183 km/s.[4] Estimates of the mass of the star range from 1.7[10] up to 2.73[4] times the mass of the Sun. It is radiating 96[4] times the Sun's luminosity from its photosphere at an effective temperature of 8,974 K.[4]