17 Crateris
Binary star system in the constellation Hydra
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17 Crateris is a wide binary star[10] system in the equatorial constellation of Hydra, located 90.5 light years away from the Sun. It is visible to the naked eye as a faint, yellow-white hued star with a combined apparent visual magnitude of 4.93.[1] The system is traversing the celestial sphere with a relative proper motion of 24.9 mas/y,[11] and is moving away from the Earth with a heliocentric radial velocity of +5.8 km/s.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra[1] |
| 17 Crt A | |
| Right ascension | 11h 32m 16.40436s[2] |
| Declination | â29° 15â² 39.6740â³[2] |
| Apparent magnitude (V) | 5.64[3] |
| 17 Crt B | |
| Right ascension | 11h 32m 16.03998s[2] |
| Declination | â29° 15â² 47.8935â³[2] |
| Apparent magnitude (V) | 5.76[3] |
| Characteristics | |
| Spectral type | F8V + F8V[3] |
| BâV color index | 0.540±0.004[1] |
| Astrometry | |
| 17 Crt A | |
| Radial velocity (Rv) | +5.8±0.4[4] km/s |
| Proper motion (μ) | RA: â19.601[2] mas/yr Dec.: +144.524[2] mas/yr |
| Parallax (Ï) | 36.0601±0.1266 mas[2] |
| Distance | 90.4 ± 0.3 ly (27.73 ± 0.10 pc) |
| Absolute magnitude (MV) | +3.48[5] |
| 17 Crt B | |
| Proper motion (μ) | RA: â22.025[2] mas/yr Dec.: +139.982[2] mas/yr |
| Parallax (Ï) | 35.9838±0.1320 mas[2] |
| Distance | 90.6 ± 0.3 ly (27.8 ± 0.1 pc) |
| Absolute magnitude (MV) | +3.57[5] |
| Details | |
| 17 Crt A | |
| Mass | 1.20[6] Mâ |
| Radius | 1.6[7] Râ |
| Luminosity | 3.2[6] Lâ |
| Surface gravity (log g) | 4.17[6] cgs |
| Temperature | 6,240[6] K |
| Metallicity [Fe/H] | 0.04±0.15[8] dex |
| Rotational velocity (v sin i) | 10.0[6] km/s |
| Age | 3.95[6] Gyr |
| 17 Crt B | |
| Mass | 1.18[6] Mâ |
| Radius | 1.5[7] Râ |
| Luminosity | 2.8[6] Lâ |
| Surface gravity (log g) | 4.20[6] cgs |
| Temperature | 6,269[6] K |
| Metallicity [Fe/H] | â0.06±0.15[8] dex |
| Rotational velocity (v sin i) | 9.6[6] km/s |
| Age | 3.67[6] Gyr |
| Other designations | |
| 17 Crt, CDâ28°8928, HIP 56280, ADS 8202, CCDM J11323-2916AB, WDS J11323-2916[9] | |
| 17 Crt A: HD 100287, HR 4444, SAO 179968 | |
| 17 Crt B: HD 100286, HR 4443, SAO 179967 | |
| Database references | |
| SIMBAD | data |
| A | |
| B | |
The dual nature of this system was discovered by W. Herschel in 1783, when they showed an angular separation of 9.8â³. As of 2015, the two components of this system had a separation of 9.60â³ along a position angle of 210°.[12] This is equivalent to a projected separation of 241.3 AU; wide enough that, thus far, their orbital track appears linear.[11] They are nearly identical F-type main-sequence stars with a stellar classification of F8V.[3] The primary is slightly brighter at magnitude 5.64, while the secondary is magnitude 5.76.[3]