51 Peg

51 Pegasi is a Sun-like star located 15.4 parsecs (50.1 light-years) from Earth in the constellation Pegasus. It was the first Sun-like star, other than the Sun, found to have a planet orbiting it, a discovery that was announced in 1995.

The exoplanet's discovery was announced on October 6, 1995 by Michel Mayor and Didier Queloz. The discovery was made with the radial velocity method at the Observatoire de Haute-Provence, using the ELODIE spectrograph.

The star itself is of apparent magnitude 5.49, and so is visible from the Earth with binoculars, or with the naked eye under dark sky conditions. 51 Pegasi is a yellow dwarf star estimated to be 7.5 billion years old, somewhat older than the Sun, 4–6% more massive, with more metal content and running low in hydrogen. Its spectral type is listed as either G2.5V or G4-5Va.

In 1996 astronomers Baliunas, Sokoloff, and Soon reported measurements of a sample of stars' Calcium II H and K spectral lines and thereby measured a rotational period of 37 days for 51 Pegasi.

Planetary system

Main article: 51 Pegasi b

After the announcement, on October 12, 1995, confirmation came from Dr. Geoffrey Marcy from San Francisco State University and Dr. Paul Butler from the University of California, Berkeley using the Hamilton Spectrograph at the Lick Observatory near San Jose in California.

51 Pegasi b (51 Peg b for short) is the first discovered planetary-mass companion of its parent star. Further such companions would be designated c, d, and so on. The planet has been informally named Bellerophon. After its discovery, many teams confirmed its existence and obtained more observations of its properties, including the fact that it orbits very close to the star, suffers estimated temperatures around 1200° Celsius, and has a minimum mass about half that of Jupiter. At the time, this close distance was not compatible with theories of planet formation and resulted in discussions of planetary migration.

See also

• PSR 1257+12
• Solar twin
• 55 Cancri
• 70 Virginis
• 47 Ursae Majoris
• Tau Boötis
• List of extrasolar planets
• List of stars in Pegasus

References

1. ^ ^{a b} Sallie Baliunas, Dmitry Sokoloff, and Willie Soon (1996). "Magnetic Field and Rotation in Lower Main-Sequence Stars: An Empirical Time-Dependent Magnetic Bode's Relation?". The Astrophysical Journal Letters 457 (2): L99–L102. doi: 10.1086/309891 . http://www.journals.uchicago.edu/doi/full/10.1086/309891 .   .
2. ^ Mayor, Michael; Queloz, Didier (1995). "A Jupiter-mass companion to a solar-type star". Nature 378 (6555): 355–359. doi: 10.1038/378355a0 .  

External links

• Extrasolar Visions : 51 Pegasi
• 51 Pegasi at SolStation.com.
• nStars database entry
• David Darling's encyclopedia

Coordinates:

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Planet Around 51PEG

The Planet Around 51 Peg Revised 04 May 2003. Velocity versus Time for 51 Peg, during one month starting 12 October 1995. (Data from Lick Observatory)

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51 Pegasi - Wikipedia, the free encyclopedia

51 Pegasi is a Sun-like star located 15.4 parsecs (50.1 light-years) from Earth in the constellation Pegasus. It was the first Sun-like star, other than the Sun, found to have a ...

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51 Pegasi page

The First Extrasolar Planet around a Solar-type Star Last update: January the 6th 2005 "The ELODIE survey for northern extra-solar planets III: Three planetary candidates ...

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the Discovery Of a Planetary Orbit Around the Nearby Star 51 Pegasi

The Discovery of a Planetary Orbit Around the Nearby Star 51Pegasus . Planetary motions around their host stars, in principle, cause small variations in the radial velocity of the ...

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51 Pegasi b - Wikipedia, the free encyclopedia

51 Pegasi b, also unofficially named Bellerophon and or abbreviated as 51 Peg b, is an extrasolar planet approximately 50 light-years away in the constellation of Pegasus. 51 ...

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- 51 Peg Remarks : The orbital distance to the star (0.05 AU) was incompatible with theoretical predictions (A. Boss, Science, 287, 360, 1995) and has triggered speculations ...

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SIMBAD query result

td1 29480 * 51 peg a gj 882 n30 5052 tyc 1717-2193-1 * 51 peg hd 217014 nltt 55385 ubv m 26734 ag +20 2595

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