Alpha Ophiuchi

light-years
Proper names: Alpha Ophiuchi, 55 Ophiuchi, Ras Alhague
Catalog numbers:
     Gliese (Gl) 681, Henry Draper (HD) 159561, Bonner Durchmusterung (BD) +12°3252, Hipparcos Input Catalog (HIC) 86032, Smithsonian Astrophysical Observatory (SAO) 102932, Fifth Fundamental Catalogue (FK5) 656, Hoffleit Bright Star (HR) 6556, New Suspected Variable (NSV) 9189
Arity: an unseen companion is suspected
Right Ascension and Declination: 17h34m56.076s, +12°33'36.14" (epoch 2000.0)
Distance from Sol: 46.7 light-years (14.3 parsecs)
Standard error in distance: 1.2443%
Source for distance: Hipparcos
Celestial (X,Y,Z) coordinates in ly: -4.98, -45.3, 10.2
Galactic (X,Y,Z) coordinates in ly: 35.0, 25.5, 17.5
Proper motion: 0.257 arcsec/yr (152.6° from north)
Radial Velocity: 12.6 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: 19.9, 1.28, -8.04

What do all these fields mean?


NOTE: This star is actually a close-orbiting binary pair. The data below are for both sub-components of the pair combined.
Spectral class: A5
Luminosity Class: III
Apparent visual magnitude: +2.08
Absolute visual magnitude: +1.30
Visual luminosity: 26.3 x Sol
Color indices: B-V= +0.15, U-B= +0.10, R-I= +0.00
Mass: 2.4 x Sol
Source for mass: Burnham's Celestial Handbook
Diameter: 3.08 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 5.13 A.U.s
Orbital period in CZ: 7.49532 years
Tidal index in CZ: 0.017800
Angular size of star in sky in CZ: 0.319977 degrees

light-years
but not more than light-years away
Data for this star system were most recently updated on 4-April-2001.