Alpha Ophiuchi
From Wikipedia, the free encyclopedia
 Ras Alhague is the α star in the constellation of Ophiuchus. |
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| Observation data Epoch J2000 |
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|---|---|
| Constellation (pronunciation) |
Ophiuchus |
| Right ascension | 17h 34m 56.1s |
| Declination | +12° 33′ 36″ |
| Apparent magnitude (V) | 2.08 |
| Characteristics | |
| Spectral type | A5 III |
| U-B color index | 0.11 |
| B-V color index | 0.15 |
| Variable type | ? |
| Astrometry | |
| Radial velocity (Rv) | +12.6 km/s |
| Proper motion (μ) | RA: 110.08 mas/yr Dec.: -222.61 mas/yr |
| Parallax (π) | 69.84 ± 0.88 mas |
| Distance | 46.7 ± 0.6 ly (14.3 ± 0.2 pc) |
| Absolute magnitude (MV) | 1.30 |
| Details | |
| Mass | 2–4 M☉ |
| Radius | 2.5 R☉ |
| Luminosity | 29.19 L☉ |
| Temperature | 8,500 K |
| Metallicity | ? |
| Rotation | ? |
| Age | ? years |
| Other designations | |
Alpha Ophiuchi (α Oph / α Ophiuchi) is the brightest star in the constellation Ophiuchus. It also has the traditional name Ras Alhague.
Ras Alhague has an apparent magnitude of +2.08, belongs to the spectral classification A5, and is about 47 light years distant from Earth.
The name Ras Alhague is from the Arabic رأس الحية (raʾs al-ḥayyah), meaning "the Head of the Serpent-charmer."
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