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System and Stellar Vitals
51 Peg
SYSTEM:
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Sky Position: |
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22h 57m 27.98s +20° 46' 07.8" [epoch 2000]
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Distance: |
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12.4 parsecs, 40.5 light years |
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Number of Suns: |
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1 |
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Estimated Age: |
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9.4 billion years* |
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Fe/H: |
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-0.03 (Sol) |
51 Pegasi:
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Mass: |
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1.11 x Sol |
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Known Planets: |
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1 |
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Appearance: |
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51 Peg |
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Sol |
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Spectral Type: |
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G2 IV** |
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Radius: |
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1.17 x Sol |
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Visual Magnitude: |
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5.5 |
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* |
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An age of 4.0 +/-2.5 Gyr is reported by Fuhrmann, et al, in their article, "Solar-type stars with planetary companions: 51 Pegasi and 47 Ursae Majoris," Astronomy & Astrophysics 326, 1081–1089, 1997. However, that age was based on 51 Pegasi as a Solar type star, not a sub-giant. As a sub-giant, this age calculation is likely no longer valid. Nordstrom, et al, report a nominal age of 9.2 Gyr in their article, "Geneva-Copenhagen Survey of Solar neighbourhood," Astronomy & Astrophysics 419, 989, 2004. If 51 Pegasi has only recently turned from the main sequence, and not yet fully a sub-giant, the age of 9.4 Gyr is calculated based on the mass of 1.11 (x Sol), and the maximum main sequence age of a star of that mass, a star of spectral type F9.5 V.
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** |
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The third Gliese Catalog of Nearby Stars (CNS3) reported the spectral type as G4 V, and others (including Fuhrmann, et al (see above note), have treated 51 Pegasi as a Solar type star. More recently, however, others have reported that 51 Peg has moved beyond the main sequence. http://simbad.u-strasbg.fr reports G2 V+, while http://exoplanet.eu reports G2 IV.
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