Alpha Hydrae

light-years
Proper names: Alphard, Cor Hydrae, Alpha Hydrae, 30 Hydrae
Catalog numbers:
     Hoffleit Bright Star (HR) 3748, Henry Draper (HD) 81797, Bonner Durchmusterung (BD) -8°2680, Smithsonian Astrophysical Observatory (SAO) 136871, Fifth Fundamental Catalogue (FK5) 354, New Suspected Variable (NSV) 4496, Caltech 2-microns Survey (IRC) -10217, Hipparcos Input Catalog (HIC) 46390
Heavy element abundance: 65% of Sol
Source for heavy element abundance: Strobel [Fe/H] Determinations
Arity: singular
Right Ascension and Declination: 9h27m35.247s, -8°39'31.15" (epoch 2000.0)
Distance from Sol: 177 light-years (54.3 parsecs)
Standard error in distance: 4%
Source for distance: Hipparcos
Celestial (X,Y,Z) coordinates in ly: -138, 108, -26.6
Galactic (X,Y,Z) coordinates in ly: -72.1, -136, 86.9
Proper motion: 0.036 arcsec/yr (23.0° from north)
Radial Velocity: -4.4 km/sec
Source for proper motion: Fifth Fundamental Catalogue
Source for radial velocity: Barbier
Galactic (U,V,W) velocity components in km/s: -0.27, 8.99, 4.92

What do all these fields mean?


Spectral class: K3
Luminosity Class: II-III
Apparent visual magnitude: +1.98
Absolute visual magnitude: -1.70
Visual luminosity: 415 x Sol
Color indices: B-V= +1.44, U-B= +1.72, R-I= +0.77
Diameter: 63.6 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 20.4 A.U.s
Angular size of star in sky in CZ: 1.662973 degrees

light-years
but not more than light-years away
Data for this star system were most recently updated on 30-September-2001.