Sigma Coronae Borealis

light-years
Proper names: Sigma Coronae Borealis, 17 Coronae Borealis, TZ Coronae Borealis
Catalog numbers:
     Gliese (Gl) 615.2, Bonner Durchmusterung (BD) +34°2750, Hipparcos Input Catalog (HIC) 79607, Smithsonian Astrophysical Observatory (SAO) 65165, Aitken Double Star (ADS) 9979, Struve (STF) 2032
Arity: trinary
Right Ascension and Declination: 16h14m41.17s, +33°51'31.6" (epoch 2000.0)
Distance from Sol: 70.7 light-years (21.7 parsecs)
Standard error in distance: 2.0811%
Source for distance: Hipparcos
Celestial (X,Y,Z) coordinates in ly: -26.1, -52.6, 39.4
Galactic (X,Y,Z) coordinates in ly: 28.6, 40.2, 50.7
Proper motion: 0.287 arcsec/yr (253.6° from north)
Radial Velocity: -12.2 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: -7.08, -29.4, 10.3

What do all these fields mean?

Data for A and B's orbit around one other:
Combined absolute visual magnitude: +3.62
Combined visual luminosity: 3.11 x Sol
Period: 1000 years
Semimajor Axis: 143 A.U.s
Eccentricity: 0.78
Periastron distance: 31.5 A.U.s
Apastron distance: 255 A.U.s
Year in which periastron occurs: 1828
Source for orbit data: W. Rabe
As seen from A:
     At periastron, B would appear as magnitude -19.04
     At apastron, B would appear as magnitude -14.50
As seen from B:
     At periastron, A would appear as magnitude -20.12
     At apastron, A would appear as magnitude -15.58

Data for B and C's orbit around one other:
Combined absolute visual magnitude: +5.03
Combined visual luminosity: 0.85 x Sol
Observed Separation: 13880 A.U.s
As seen from B:
     C would appear as magnitude -0.23
As seen from C:
     B would appear as magnitude -5.82


Component A:
NOTE: This star is actually a close-orbiting binary pair. The data below are for both sub-components of the pair combined.
Catalog numbers:
     Henry Draper (HD) 146361, Hoffleit Bright Star (HR) 6063
Spectral class: F8
Luminosity Class: V
Apparent visual magnitude: +5.64
Absolute visual magnitude: +3.96
Visual luminosity: 2.27 x Sol
Variable type: RS Canum Venaticorum (eclipsing binary)
Period of variability: 1.1 days
Color indices: B-V= +0.51, U-B= +0.00, R-I= +0.21
Diameter: 1.07 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 1.51 A.U.s
Angular size of star in sky in CZ: 0.378432 degrees


Component B:
Catalog numbers:
     Henry Draper (HD) 146362, Hoffleit Bright Star (HR) 6064
Right Ascension and Declination: 16h14m40.8s, +33°51'30" (epoch 2000.0)
Celestial (X,Y,Z) coordinates in ly: -26.1, -52.6, 39.4
Galactic (X,Y,Z) coordinates in ly: 28.6, 40.2, 50.7
Proper motion: 0.287 arcsec/yr (253.6° from north)
Radial Velocity: -14.5 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: -8.01, -30.7, 8.65
Spectral class: G1
Luminosity Class: V
Apparent visual magnitude: +6.72
Absolute visual magnitude: +5.04
Visual luminosity: 0.84 x Sol
Color indices: R-I= +0.24
Diameter: 0.97 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 0.92 A.U.s
Angular size of star in sky in CZ: 0.564140 degrees


Component C:
Catalog numbers:
     Giclas (G) 180-42, Luyten (L) 1490-24, Luyten Two-Tenth (LTT) 14836
Right Ascension and Declination: 16h12m3s, +33°53'54" (epoch 1950.0)
Celestial (X,Y,Z) coordinates in ly: -26.6, -52.3, 39.5
Galactic (X,Y,Z) coordinates in ly: 28.4, 39.8, 51.1
Proper motion: 0.305 arcsec/yr (254.0° from north)
Radial Velocity: -12.2 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: -7.66, -30.7, 11.3
Spectral class: M3.5
Luminosity Class: V
Apparent visual magnitude: +12.31
Absolute visual magnitude: +10.63
Visual luminosity: 0.0049 x Sol
Color indices: B-V= +1.40, R-I= +1.04
Comfort Zone (visual): 0.070 A.U.s

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