![]() ![]() Location of α Ophiuchi (circled) |
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Observation data Epoch J2000 Equinox J2000 |
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Constellation | Ophiuchus |
Right ascension | 17 |
Declination | +12° 33′ 36.1346″ |
Apparent magnitude (V) | 2.07 |
Characteristics | |
Spectral type | A5 III |
U−B color index | +0.10 |
B−V color index | +0.15 |
Astrometry | |
Radial velocity (Rv) | +12.6 km/s |
Proper motion (μ) | RA: 108.07 mas/yr |
Parallax (π) | 67.13 ± 1.06mas |
Distance | 48.6 ± 0.8 ly (14.9 ± 0.2 pc) |
Absolute magnitude (MV) | 1.30 |
Orbit | |
Period (P) | 3,148.4 days |
Semimajor axis (a) | 427+20 −13 mas |
Eccentricity (e) | 0.92 ± 0.03 |
Inclination (i) | 125+6 −9° |
Longitude of the node (Ω) | 232 ± 9° |
Periastron epoch (T) | 2452888 ± 53 JD |
Argument of periastron (ω) (secondary) |
162 ±14° |
Details | |
α Oph A | |
Mass | 2.40+.23 −.37M☉ |
Radius | 2.6R☉ |
Luminosity | 25.1–25.6L☉ |
Surface gravity (log g) | 3.91 |
Temperature | 7,880–8,050K |
Rotational velocity (v sin i) | 240 km/s |
Age | 0.77 ± 0.03Gyr |
α Oph B | |
Mass | 0.85+.06 −.04M☉ |
Other designations | |
Ras Alhague, Rasalhague, 55 Ophiuchi, BD +12° 3252, FK5 656, GCTP 4000.00, Gl 681, HD 159561, HIP 86032, HR 6556, SAO 102932.
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