Omicron(2) Eridani

light-years
Proper names: Keid, Omicron(2) Eridani, 40 Eridani, Omicron Eridani
Catalog numbers:
     Gliese (Gl) 166, Hipparcos Input Catalog (HIC) 19849, Smithsonian Astrophysical Observatory (SAO) 131063, Hoffleit Bright Star (HR) 1325
Heavy element abundance: 71% of Sol
Standard error in heavy element abundance: 23%
Source for heavy element abundance: Strobel [Fe/H] Determinations
Arity: trinary
Right Ascension and Declination: 4h15m16.314s, -7°39'9.88" (epoch 2000.0)
Distance from Sol: 16.45 light-years (5.044 parsecs)
Standard error in distance: 0.4219%
Source for distance: Hipparcos
Celestial (X,Y,Z) coordinates in ly: 7.195, 14.63, -2.191
Galactic (X,Y,Z) coordinates in ly: -12.19, -4.677, -10.01
Proper motion: 4.083 arcsec/yr (213.1° from north)
Radial Velocity: -42.7 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: 97.01, -12.01, -42.40

What do all these fields mean?

Data for A and (B-C)'s orbit around one other:
Combined absolute visual magnitude: +5.90
Combined visual luminosity: 0.380 x Sol
Observed Separation: 417.7 A.U.s
Year of separation observation: 1783
Source for orbit data: William Herschel
As seen from A:
     (B-C) would appear as magnitude -7.68
As seen from (B-C):
     A would appear as magnitude -12.56

Data for B and C's orbit around one other:
Combined absolute visual magnitude: +10.79
Combined visual luminosity: 0.00420 x Sol
Period: 252.1 years
Semimajor Axis: 35.02 A.U.s
Eccentricity: 0.41
Periastron distance: 20.66 A.U.s
Apastron distance: 49.38 A.U.s
Year in which periastron occurs: 1849.6
Source for orbit data: W.D. Heintz
As seen from B:
     At periastron, C would appear as magnitude -12.34
     At apastron, C would appear as magnitude -10.45
As seen from C:
     At periastron, B would appear as magnitude -13.99
     At apastron, B would appear as magnitude -12.10


Component A:
Catalog numbers:
     Henry Draper (HD) 26965, Bonner Durchmusterung (BD) -7780, Luyten Half-Second (LHS) 23, Luyten Two-Tenth (LTT) 1907
Spectral class: K1e
Luminosity Class: V
Apparent visual magnitude: +4.43
Absolute visual magnitude: +5.91
Visual luminosity: 0.376 x Sol
Color indices: B-V= +0.82, U-B= +0.45, R-I= +0.31
Mass: 0.75 x Sol
Source for mass: Burnham's Celestial Handbook
Diameter: 1.063 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 0.613 A.U.s
Orbital period in CZ: 202.515 days
Tidal index in CZ: 3.25286
Angular size of star in sky in CZ: 0.923825 degrees


Component B:
Catalog numbers:
     Henry Draper (HD) 26976, Bonner Durchmusterung (BD) -7781, Giclas (G) 160-60, Luyten Half-Second (LHS) 24, Aitken Double Star (ADS) 3093, Eggen/Greenstein white dwarf (EG) 33, Luyten Two-Tenth (LTT) 1908, Struve (STF) 518
Right Ascension and Declination: 4h13m4s, -7°44'6" (epoch 1950.0)
Celestial (X,Y,Z) coordinates in ly: 7.334, 14.56, -2.214
Galactic (X,Y,Z) coordinates in ly: -12.13, -4.593, -10.13
Proper motion: 4.073 arcsec/yr (212.4° from north)
Radial Velocity: -21 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: 81.20, -19.27, -54.41
Spectral class: DA4
Luminosity Class: wd
Apparent visual magnitude: +9.52
Absolute visual magnitude: +11.01
Visual luminosity: 0.00345 x Sol
Color indices: B-V= +0.03, U-B= -0.68, R-I= -0.10
Mass: 0.44 x Sol
Source for mass: Burnham's Celestial Handbook
Diameter: 0.019 x Sol
Source for diameter: Burnham's Celestial Handbook
Comfort Zone (visual): 0.0587 A.U.s
Orbital period in CZ: 7.83406 days
Tidal index in CZ: 2173.74
Angular size of star in sky in CZ: 0.172513 degrees


Component C:
Proper names: DY Eridani
Catalog numbers:
     Henry Draper (HD) 26976, Luyten Half-Second (LHS) 25, Aitken Double Star (ADS) 3093, Luyten Two-Tenth (LTT) 1909, Struve (STF) 518
Right Ascension and Declination: 4h13m4s, -7°44'6" (epoch 1950.0)
Celestial (X,Y,Z) coordinates in ly: 7.334, 14.56, -2.214
Galactic (X,Y,Z) coordinates in ly: -12.13, -4.593, -10.13
Proper motion: 4.073 arcsec/yr (212.4° from north)
Radial Velocity: -45.9 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: 99.55, -12.32, -39.09
Spectral class: M4.5e
Luminosity Class: V
Apparent visual magnitude: +11.17
Absolute visual magnitude: +12.66
Visual luminosity: 0.000754 x Sol
Variable type: UV Ceti flare star (eruptive variable)
Color indices: B-V= +1.67, U-B= +0.83, R-I= +1.31
Mass: 0.15 x Sol
Diameter: 0.28 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 0.0275 A.U.s
Orbital period in CZ: 4.29184 days
Tidal index in CZ: 7242.6
Angular size of star in sky in CZ: 5.435548 degrees

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