Delta Geminorum

light-years
Proper names: Delta Geminorum, Wasat, 55 Geminorum
Catalog numbers:
     Gliese (Gl) 271, Henry Draper (HD) 56986, Bonner Durchmusterung (BD) +22°1645, Hipparcos Input Catalog (HIC) 35550, Smithsonian Astrophysical Observatory (SAO) 79294, Aitken Double Star (ADS) 5983, Fifth Fundamental Catalogue (FK5) 279, Hoffleit Bright Star (HR) 2777, Struve (STF) 1066
Arity: binary
Right Ascension and Declination: 7h20m7.367s, +21°58'56.29" (epoch 2000.0)
Distance from Sol: 58.8 light-years (18.0 parsecs)
Standard error in distance: 1.5098%
Source for distance: Hipparcos
Celestial (X,Y,Z) coordinates in ly: -18.7, 51.2, 22.0
Galactic (X,Y,Z) coordinates in ly: -54.1, -15.9, 16.7
Proper motion: 0.029 arcsec/yr (239.1° from north)
Radial Velocity: -15.3 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: 13.5, 3.63, -6.70

What do all these fields mean?

Data for A and B's orbit around one other:
Combined absolute visual magnitude: +2.23
Combined visual luminosity: 11.1 x Sol
Period: 1200 years
Semimajor Axis: 126 A.U.s
Eccentricity: 0.11
Periastron distance: 112 A.U.s
Apastron distance: 140 A.U.s
Year in which periastron occurs: 1437
Source for orbit data: J. Hopmann
As seen from A:
     At periastron, B would appear as magnitude -14.41
     At apastron, B would appear as magnitude -13.93
As seen from B:
     At periastron, A would appear as magnitude -19.08
     At apastron, A would appear as magnitude -18.60


Component A:
NOTE: This star is actually a close-orbiting binary pair. The data below are for both sub-components of the pair combined.
Spectral class: F1
Luminosity Class: IV-V
Apparent visual magnitude: +3.53
Absolute visual magnitude: +2.25
Visual luminosity: 11.0 x Sol
Color indices: B-V= +0.34, U-B= +0.04, R-I= +0.10
Diameter: 3.10 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 3.31 A.U.s
Angular size of star in sky in CZ: 0.499134 degrees


Component B:
Proper motion: 0.029 arcsec/yr (239.1° from north)
Radial Velocity: 2.2 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: -2.60, -1.10, -1.73
Spectral class: K3
Luminosity Class: V
Apparent visual magnitude: +8.20
Absolute visual magnitude: +6.92
Visual luminosity: 0.15 x Sol
Diameter: 0.75 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 0.39 A.U.s
Angular size of star in sky in CZ: 1.037053 degrees

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