Donner 91

light-years

Catalog numbers:
     Gliese (Gl) 185, Henry Draper (HD) 32450, Bonner Durchmusterung (BD) -21°1051, Hipparcos Input Catalog (HIC) 23452, Smithsonian Astrophysical Observatory (SAO) 170003, Vyssotsky McCormick (McC) 112, Donner (DON) 91
Arity: binary
Right Ascension and Declination: 5h2m28.4s, -21°15'25.45" (epoch 2000.0)
Distance from Sol: 27.8 light-years (8.52 parsecs)
Standard error in distance: 1.5186%
Source for distance: Hipparcos
Celestial (X,Y,Z) coordinates in ly: 6.43, 25.1, -10.1
Galactic (X,Y,Z) coordinates in ly: -17.5, -15.6, -14.9
Proper motion: 0.308 arcsec/yr (211.1° from north)
Radial Velocity: -17.2 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: 19.9, 7.28, 1.12

What do all these fields mean?

Data for A and B's orbit around one other:
Combined spectrum: K7 V
Combined absolute visual magnitude: +8.65
Combined visual luminosity: 0.030 x Sol
Period: 42.7 years
Semimajor Axis: 11.9 A.U.s
Eccentricity: 0.83
Periastron distance: 2.03 A.U.s
Apastron distance: 21.8 A.U.s
Year in which periastron occurs: 1952.9
Source for orbit data: W.D. Heintz
As seen from A:
     At periastron, B would appear as magnitude -19.19
     At apastron, B would appear as magnitude -14.03
As seen from B:
     At periastron, A would appear as magnitude -21.23
     At apastron, A would appear as magnitude -16.07


Component A:
Apparent visual magnitude: +8.46
Absolute visual magnitude: +8.81
Visual luminosity: 0.026 x Sol
Mass: 0.35 x Sol
Diameter: 0.62 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 0.16 A.U.s
Orbital period in CZ: 40.0965 days
Tidal index in CZ: 82.979
Angular size of star in sky in CZ: 2.054333 degrees


Component B:
Spectral class: M
Luminosity Class: V
Apparent visual magnitude: +10.50
Absolute visual magnitude: +10.85
Visual luminosity: 0.0040 x Sol
Mass: 0.2 x Sol
Diameter: 0.39 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 0.063 A.U.s
Orbital period in CZ: 12.9597 days
Tidal index in CZ: 794.31
Angular size of star in sky in CZ: 3.292574 degrees

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