51 Pegasi
Proper names: 51 Pegasi
Catalog numbers:
Gliese (Gl) 882, Henry Draper (HD) 217014, Bonner Durchmusterung (BD) +19°5036, Hipparcos Input Catalog (HIC) 113357, Smithsonian Astrophysical Observatory (SAO) 90896, Hoffleit Bright Star (HR) 8729, New Suspected Variable (NSV) 14374, Luyten Two-Tenth (LTT) 16750
Age: 8500 million years
Source for age: B. Edvardsson et al., "Chemical Evolution of the Galactic Disc", A&AP 275
Heavy element abundance: 200% of Sol
Source for heavy element abundance: B. Edvardsson et al., "Chemical Evolution of the Galactic Disc", A&AP 275
Arity: singular
Points of interest:
This is the first sunlike star outside of our own solar system around which a planet was actually detected. On the 6th of October 1995, Michel Mayor and Didier Queloz of the Geneva Observatory in Switzerland detected a regular variation in the doppler-shift of the light coming off 51 Pegasi, indicating a closely orbiting companion. One week later, Geoffrey Marcy and Paul Butler confirmed it at Lick Observatory. The planet (unofficially dubbed Bellerophon by Marcy) has at most half the mass of Jupiter, and follows a nearly-perfect circular orbit at a distance of 8 million kilometers (0.05 AU) with a period of 4.2293 days. Being so close to the star would give the planet a surface temperature of over 1100 K if it is rotating (which it almost certainly is).
Right Ascension and Declination: 22h57m27.965s, +20°46'7.1" (epoch 2000.0)
Distance from Sol: 50.1 light-years (15.4 parsecs)
Standard error in distance: 1.154%
Source for distance: Hipparcos
Celestial (X,Y,Z) coordinates in ly: 45.1, -12.6, 17.8
Galactic (X,Y,Z) coordinates in ly: -0.60, 41.1, -28.6
Proper motion: 0.208 arcsec/yr (76.9° from north)
Radial Velocity: -33.7 km/sec
Source for proper motion and radial velocity: Gliese
Galactic (U,V,W) velocity components in km/s: -14.0, -30.4, 15.5
What do all these fields mean?
Spectral class: G2-3
Luminosity Class: V
Apparent visual magnitude: +5.47
Absolute visual magnitude: +4.54
Visual luminosity: 1.33 x Sol
Color indices: B-V= +0.67, U-B= +0.21, R-I= +0.22
Mass: 1.1 x Sol
Diameter: 1.27 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 1.16 A.U.s
Orbital period in CZ: 1.18369 years
Tidal index in CZ: 0.71372
Angular size of star in sky in CZ: 0.586693 degrees
Detected companions: 1
Companion Bellerophon:
Mass: 0.5 x Jupiter
Source for mass: Mayor, Queloz, Marcy, Butler
Diameter: 1.3 x Jupiter
Standard error in diameter: 7.6923%
Source for diameter: Guillot et al. (1996)
Period: 4.2293 days
Semimajor Axis: 0.05 A.U.s
Eccentricity: 0
Periastron distance: 0.05 A.U.s
Apastron distance: 0.05 A.U.s
Source for orbit data: Mayor, Queloz, Marcy, Butler
Data for this star system were most recently updated on 12-May-2001.