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Topic: 51 Pegasi

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  51 Pegasi
With the exception of some pulsar planets, 51 Pegasi b was the first extrasolar planet to be found.
51 Pegasi b orbits its host star at less than one eighth the distance of Mercury from the Sun so that, assuming it has a radius of 1.2 to 1.4 that of Jupiter, it must have a surface temperature of around 1,000°C.
In 2001, astronomers at the University of Texas at Arlington published results showing that the habitable zone around 51 Pegasi, where an inner rocky planet (with suitable mass and atmospheric composition and density) can have liquid water on its surface, lies between 1.20 and 2.0 AU of the star.
www.daviddarling.info /encyclopedia/A/51Peg.html   (493 words)

 51 Pegasi b - Wikipedia, the free encyclopedia
51 Pegasi b (or 51 Peg b for short) is the first planet discovered around a sun-like star outside the solar system.
It orbits the star 51 Pegasi in the Pegasus constellation.
It is sufficiently massive that its thick atmosphere is not blown away by the star's solar wind.
en.wikipedia.org /wiki/51_Pegasi_b   (616 words)

 Extrasolar Visions - 51 Pegasi b
When 51 Pegasi b was first discovered, one theory was that it was a titanic terrestrial world, a rocky planet with the mass of Jupiter.
51 Pegasi b has about the same calculated temperature as HD 209458 b, so there is a good chance that its atmosphere is evaporating to some degree as well, although direct observations would be required to verify this.
The night side of 51 Pegasi b is aglow with the heat of the planet's formation from beneath dark silicate clouds.
www.extrasolar.net /planet.asp?PlanetID=1   (1988 words)

 Does 51 Pegasi's Planet Really Exist?
Above: The radial (line-of-sight) velocity of 51 Pegasi varies sinusoidally with a 4.231-day period and 56 meter/second amplitude, suggesting that the star is circled by a companion with a minimum mass of 0.47 Jupiter.
He also points out that 51 Pegasi seems to be older than the Sun and has begun to wander from the hydrogen-burning main sequence; maybe it is susceptible to instabilities that aren't seen in younger stars.
In October 1995 astronomers in Switzerland announced that 51 Pegasi, a solar-type star 50 light-years distant, is closely orbited by a giant planet.
exoplanets.org /no51pegb.html   (2057 words)

 Extrasolar Planets - 51 Pegasi
As close as 0,05 AU to its parent star, 51 Pegasi b has an average temperature of 1.300°C, sufficiently high to melt aluminium.
There was much debate about 51 Pegasi b, especially since the star shows some fluctuations with a very similar periodicity than the presumed planet.
But now all remaining doubts are removed, and 51 Pegasi b is a confirmed planet, very important for all subsequent discoveries of extrasolar worlds.
www.exoplaneten.de /51peg/english.html   (306 words)

 Pegasus Constellation   (Site not responding. Last check: 2007-10-13)
Pegasus is a large,well-populated constellation with several points of interest, including 51 Pegasi, which is thought to have a planet in orbit.
Kappa Pegasi is a very close binary, with an orbit of only 11.52 years: 4.8, 5.3; presently the companion is at PA 132 degrees and separation of only 0.2".
Epsilon Pegasi is an irregular (Lb type) variable, and a flare star with a relatively cool shell.
home.xtra.co.nz /hosts/Wingmakers/Pegasus.html   (1160 words)

 eSky: 51 Pegasi   (Site not responding. Last check: 2007-10-13)
51 Pegasi is important as possessing a planetary system.
51 Pegasi lies about halfway along the western side of the Square of Pegasus.
Possible appearance of a large gas giant in the 51 Pegasi system, designated 51 Pegasi b, shown here with two hypothetical moons.
www.glyphweb.com /esky/stars/51pegasi.html   (92 words)

 51 Pegasi
As 51 Pegasi has become one of the top 100 target stars for NASA's planned Terrestrial Planet Finder (TPF), images of this star and its position relative to the Milky Way in Earth's night sky are now available from the TPF-C team.
On February 19, 2006, Margaret Turnbull named 51 Pegasi as a Sun-like star that is old enough to qualify as a top-five candidate for those listening for radio signals from intelligent civilizations, such as the SETI Institute.
51 Pegasi is a yellow-orange main sequence dwarf star of spectral and luminosity type G4-5 Va, but it had been previously classified as G2-2.5 and sometimes as a subgiant (IV).
www.solstation.com /stars2/51pegasi.htm   (900 words)

 [No title]
Measurements at ESO claim to constraint the photometric variablity of the host star, 51 pegasi, to be 0.002 mag or less.
In other words, we can be very, very confident that 51 Peg is *not* rotating with a 4.2 day period, leading to its imitating the presence of a planet (perhaps through spots), because at 1 solar mass a 4.2 day period corresponds to a star that's just reached the ZAMS, and they are *very* active.
The goal was to detect the wobble of 51 Peg in response to the gravitational pull of the supposed planet.
zebu.uoregon.edu /51peg.html   (2336 words)

 51 Pegasi - Wikipedia, the free encyclopedia
51 Pegasi is a Sun-like star 15.4 parsecs (50.1 light-years) from Earth in the constellation Pegasus.
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.
51 Pegasi b or 51 Peg b for short is the first discovered planetary-mass companion of its parent star.
en.wikipedia.org /wiki/51_Pegasi   (423 words)

 What's Up - Featured Deep Sky Objects
51 Pegasi is another nearby star much like our sun recently found to be attended by a giant planet - in this case, the planet defied expectations by orbiting much closer to its star than Mercury does ours, making for a ferociously hot environment.
While 51 Pegasi is not suitable for life, it is very easy to find - perhaps the easiest of all such systems.
Look along the west side of the great square, between Markab and Scheat, and you'll be able to spot 51 Pegasi easily in binoculars or even with your eyes if the sky is fairly dark.
www.sciencecenter.net /whatsup/11/51-peg.htm   (169 words)

 Will a Second Planet Be Discovered around 51 Pegasi?   (Site not responding. Last check: 2007-10-13)
The Sun-like star, 51 Pegasi, that yielded one recently discovered planet is unlikely to yield another--at least not one as massive as ten Jupiters.
Because the AFOE data on 51 Pegasi extend back to 1993--further back than the Swiss data--the AFOE team was able to analyze nearly 100 separate observations to separate out the effects of the newly discovered planet and see if other, longer-term signals were present from a second planet.
Based on their analyses to date, the NCAR scientists conclude that "there is probably not an object larger than ten Jupiter masses closer to 51 Pegasi than two astronomical units [roughly the distance between the Sun and Mars]," says Brown.
www.ucar.edu /communications/newsreleases/1996/pegasi.html   (702 words)

 51 Pegasi: The Discovery of a New Planet
We enter this realm of discovery by working with actual data from observations of the star 51 Pegasi (51 Peg) made at the Lick Observatory in California.
These data are the measurements of the Doppler shift of the wavelengths of the absorption lines seen in the spectra of 51 Peg.
This wobble of the star was the first indication that the star 51 Peg had an invisible companion.
www.astro.washington.edu /labs/clearinghouse/labs/51Peg/51pegasi.html   (472 words)

 Extrasolar Planets - 51 Pegasi
A una distancia de 0,05 UA de su estrella, 51 Pegasi b tiene una temperatura media de 1.300°C, suficientemente alta como para fundir el aluminio.
Hubo mucho debate sobre 51 Pegasi b, especialmente teniendo en cuenta que la estrella muestra algunas fluctuaciones de periodicidad similar al supuesto planeta.
En esta recreación asumimos que 51 Pegasi b es un planeta supermasivo de tipo terrestre.
www.exoplaneten.de /51peg/spanish.html   (311 words)

 Notes for 51 Peg
This question was implicitely raised by a paper by the PTI team claiming that the 51 Peg system may be resolved.
A planetary companion for 51 Pegasi implied by absence of pulsations in the stellar spectra.
Absence of a planetary signature in the spectra of 51 Pegasi.
www.obspm.fr /encycl/51Peg.html   (940 words)

 Astrobiology: The Living Universe - Where to look for ET life
The planet orbiting 51 Pegasi (named 51 Pegasi B) may be the first ever planet to be discovered orbiting a normal star roughly the size of the sun.
51 Pegasi is a G-type star (G2-3 main sequence, to be exact) 42 light years from Earth.
51 Pegasi B was detected using the 'wobble' method where anomalies in the star's radial velocity indicated that it was under the influence of a large planet nearby.
library.thinkquest.org /C003763/index.php?page=findlife04   (1231 words)

 NASA's Solar System Exploration: Planets: Beyond Our Solar System: Overview
It was discovered by noting a slight perturbation in the position of 51 Pegasi, a star in our nearby galactic neighborhood.
The newly found planet orbiting 51 Peg had a size comparable to Jupiter or Saturn, however, it was positioned extremely close to its parent star - closer than Mercury sits from our own Sun.
Some of them are orbiting extremely close to their parent star like the 51 Peg planetary system, while others are found to be at distances comparable to where Mars and Jupiter orbit in our solar system.
solarsystem.nasa.gov /planets/profile.cfm?Object=Beyond&Display=OverviewLong   (563 words)

 APOD: December 1, 1995 - 51 Pegasi: A New Planet Discovered   (Site not responding. Last check: 2007-10-13)
Humanity took one step closer to answering these questions in October 1995 when it was announced that the star 51 Pegasi harbors at least one planet.
In the above picture of 51 Peg the planet is not visible - it can only be detected by noticing small changes in the star's motion.
In the above picture the lines centered on 51 Peg are caused by the telescope itself and are not related to the star or planet.
antwrp.gsfc.nasa.gov /apod/ap951201.html   (196 words)

 The Planet around 51 Pegasi   (Site not responding. Last check: 2007-10-13)
We have obtained over 100 radial velocity measurements of 51 Peg at a precision of 5 \ms, spanning 2 months.
We confirm the report of Mayor and Queloz that its velocity varies with a period of 4.22d and low amplitude, indicative of a planetary companion.
The sinusoidal velocities are superimposed on a linear increase in velocity, dv/dt = 0.7 \ms per day, indicating the presence of a second companion having mass greater than 10 \mjup and period greater than \sim1 yr.
www.aas.org /publications/baas/v27n4/aas187/S070004.html   (149 words)

 Homework 3 Solutions
The planet around 51 Pegasi orbits with an average distance (semimajor axis) of 0.051 AU - much closer to its star than Mercury is to our Sun.
At 0.6 times the mass of Jupiter, the planet in 51 Pegasi seems likely to be a jovian planet.
It is also conceivable that the 51 Peg nebula was much denser and allowed larger planets to form; in this case, the planet might actually be a very large terrestrial planet.
www.pha.jhu.edu /~c171_118/homework3.html   (988 words)

 51 Pegasi
However, planet-hunters are rising to 51 Peg's defense, arguing that the pulsations Gray envisions can't become strong enough to reproduce the observed behavior.
Although the researchers had not observed the planet directly, they based their conclusion on the periodic movements in the position of lines in the spectrum of light surrounding the star, 51 Pegasi (pronounced Peg-a-see).
Gray's examination of the spectral lines around 51 Pegasi indicates that they are not only moving, but changing shape.
www.xs4all.nl /~carlkop/51peg.html   (788 words)

 Extra solar planets: Gas giants, Space Art, 51 Pegasi, 55 Cancri, Tau Bootis, 47 Ursae Majoris, 70 Virginis
51 Pegasi B, or Bellerophon as the gas giant has been dubbed, was the first extrasolar planet to be discovered around a sunlike star.
The planet may be so hot that the gas in the atmosphere is driven away by the heat and solar winds, creating a similar faint and comet-like tail that also might be found around the planet 51 Pegasi (which is named Bellephoron).
Space art 1: 51 Pegasi b, Bellerophon, seen from the surface of the parent star.
www.novacelestia.com /space_art_extrasolar_planets/gas_giants.html   (2592 words)

 51 Pegasi: Planet, Not Pulsation by Ken Croswell
Their delight comes at the expense of a rival theory which claimed that the planet was simply a mirage.
In 1995, Michel Mayor and Didier Queloz of the Geneva Observatory reported that 51 Pegasi is wobbling from the gravitational pull of an orbiting planet.
Early in 1997, however, David Gray of the University of Western Ontario in Canada asserted that 51 Pegasi's planet did not exist.
www.sonic.net /~antares/51Pegasi.html   (296 words)

 51 Pegasi and Tau Boötis: Planets or Pulsations?   (Site not responding. Last check: 2007-10-13)
It has recently been suggested (Gray 1997) that the radial velocity variations observed in the spectra of 51 Pegasi are the result of stellar pulsations as opposed to the reflex motion due to an orbital companion.
The AFOE group has confirmed the radial velocity variations in 51 Pegasi and tau Bootis.
Here we discuss the results of a search for evidence of pulsations in the AFOE data for these two stars, as well as attempt to clear up misconceptions regarding pulsations circulated as a result of the current debate about the nature of the 51 Pegasi radial velocity variations.
cfa-www.harvard.edu /afoe/cs10-97-poster.html   (153 words)

 Other Solar Systems
If this is due to orbital motion, these numbers suggest that a planet lies only 7 million kilometers from 51 Pegasi -- much closer than Mercury is to the Sun -- and that the planet has a mass at least half that of Jupiter.
Probably lacking an atmosphere, the planet may be a nearly molten ball of iron and rock with seven times the Earth's diameter and seven times its surface gravity.
These were discovered using the same doppler shift technique that found the planet orbiting 51 Pegasi.
www.wanderer.org /nineplanets/other.html   (1527 words)

 51 Pegasi   (Site not responding. Last check: 2007-10-13)
The circle shows the location of the sunlike class G star 51 Pegasi (in the constellation Pegasus).
That is only 7.5 million kilometers, 4.6 million miles, or 13 percent Mercury's distance from the Sun.
51 Pegasi, 50 light years away, is a fifth magnitude (5.49, just short of sixth magnitude) star 1.3 times more luminous than the
www.astro.uiuc.edu /~kaler/sow/51peg.html   (148 words)

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