51 Pegasi

Starbox begin
name = 51 PegasiStarbox image


caption = The red circle shows the location of 51 Pegasi in Pegasus. Starbox observe
epoch = J2000.0
constell = Pegasus
ra = RA|22|57|28.0
dec = DEC|+20|46|08
appmag_v = 5.49 Starbox character
class = G2.5IVa "or" G4-5Va
r-i = 0.32
v-r = 0.37
b-v = 0.67
u-b = 0.22
variable = SuspectedStarbox astrometry
radial_v = -33.7
prop_mo_ra = 208.07
prop_mo_dec = 60.96
parallax = 65.10
p_error = 0.76
dist_ly = 50.1
dist_pc = 15.4
absmag_v = 4.51Starbox detail
mass = 1.06
radius = 1.15–1.4
density = 544–981
gravity = 3.89–4.21
luminosity = 1.30
temperature = 5,665
metal = 160%
rotation = 37 days
age = 7.5–8.5 × 10⁹Starbox catalog
names = GJ 882, HR 8729, BD +19°5036, HD 217014, LTT 16750, GCTP 5568.00, SAO 90896, HIP 113357.

51 Pegasi is a Sun-like star (although somewhat older than the Sun) located 15.4 parsecs (50.1 light-years) from Earth in the constellation Pegasus. It was the first Sun-like star 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.cite journal| author=Mayor "et al." | title=A Jupiter-mass companion to a solar-type star | journal=Nature | year=1995 | volume=378 | issue= | pages=355–359 | doi= 10.1038/378355a0] 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. cite journal | author=Sallie Baliunas, Dmitry Sokoloff, and Willie Soon | title=Magnetic Field and Rotation in Lower Main-Sequence Stars: An Empirical Time-Dependent Magnetic Bode's Relation? | journal=The Astrophysical Journal Letters | volume=457 | issue=2 | year=1996 | pages=L99–L102 | url=http://www.journals.uchicago.edu/doi/full/10.1086/309891 .]

Planetary system

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.

PlanetboxOrbit
exoplanet = b
mass = >0.468 ± 0.007
period = 4.23077 ± 0.00005
semimajor = 0.052
eccentricity = 0

See also

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

References

External links

* [http://www.extrasolar.net/startour.asp?StarCatID=normal&StarID=1 Extrasolar Visions: 51 Pegasi]
* [http://www.solstation.com/stars2/51pegasi.htm 51 Pegasi] at SolStation.com.
* [http://www.ari.uni-heidelberg.de/aricns/cnspages/4c01878.htm ARICNS]
* [http://nstars.arc.nasa.gov/searches/starinfo.cfm?partb=2257p2046&starpage=0 nStars database entry]
* [http://www.daviddarling.info/encyclopedia/A/51Peg.html David Darling's encyclopedia]