Gliese 65
Gliese 65, also known as Luyten 726-8, is a binary star system that is one of Earth's nearest neighbors, at 8.8 light-years (2.7 parsecs) from Earth in the constellation Cetus. The two component stars are both flare stars with the variable star designations BL Ceti and UV Ceti.
Gliese 65 Location of Gliese 65 in the constellation Cetus | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus |
| Gliese 65 A (BL Ceti) | |
| Right ascension | 01h 39m 01.3773s |
| Declination | –17° 57′ 02.587″ |
| Apparent magnitude (V) | 12.8 |
| Gliese 65 B (UV Ceti) | |
| Right ascension | 01h 39m 01.6377s |
| Declination | –17° 57′ 01.001″ |
| Apparent magnitude (V) | 12.8 |
| Characteristics | |
| Gliese 65 A (BL Ceti) | |
| Spectral type | M5.5V |
| U−B color index | 1.10 |
| B−V color index | 1.87 |
| Variable type | UV Cet |
| Gliese 65 B (UV Ceti) | |
| Spectral type | M6 V |
| Variable type | UV Cet |
| Astrometry | |
| Parallax (π) | 371.92 ± 0.42 mas |
| Distance | 8.770 ± 0.010 ly (2.689 ± 0.003 pc) |
| Gliese 65 A (BL Ceti) | |
| Proper motion (μ) | RA: 3385.316 mas/yr Dec.: 544.386 mas/yr |
| Absolute magnitude (MV) | 15.7 |
| Gliese 65 B (UV Ceti) | |
| Proper motion (μ) | RA: 3178.694 mas/yr Dec.: 584.061 mas/yr |
| Absolute magnitude (MV) | 15.7 |
| Orbit | |
| Period (P) | 26.38±0.002 yr |
| Semi-major axis (a) | 2.0584±0.0097" (5.459±0.002 AU) |
| Eccentricity (e) | 0.6172±0.0001 |
| Inclination (i) | 128.0±0.1° |
| Longitude of the node (Ω) | 325.9±0.1° |
| Periastron epoch (T) | 41333±8 MJD (17 January 1972) |
| Argument of periastron (ω) (secondary) | 103.2±0.1° |
| Details | |
| Gliese 65 A | |
| Mass | 0.122±0.002 M☉ |
| Radius | 0.165±0.006 R☉ |
| Luminosity | 0.00147±0.00005 L☉ |
| Surface gravity (log g) | 5.092±0.015 cgs |
| Temperature | 2784±58 K |
| Metallicity [Fe/H] | −0.03±0.20 dex |
| Rotation | 0.2430±0.0005 days |
| Rotational velocity (v sin i) | 28.2±2 km/s |
| Gliese 65 B | |
| Mass | 0.116±0.002 M☉ |
| Radius | 0.159±0.006 R☉ |
| Luminosity | 0.00125±0.00005 L☉ |
| Surface gravity (log g) | 5.113±0.015 cgs |
| Temperature | 2728±60 K |
| Metallicity [Fe/H] | −0.12±0.20 dex |
| Rotation | 0.2268±0.0003 days |
| Rotational velocity (v sin i) | 30.6±2 km/s |
| Other designations | |
| Gliese 65 A: BL Ceti, LHS 9 | |
| Gliese 65 B: UV Ceti, LHS 10 | |
| Database references | |
| SIMBAD | The system |
| A (BL Cet) | |
| B (UV Cet) | |
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