51 Pegasi (Flamsteed designation, HIP 113357 in the Hipparcos Catalogue, HD 217014 in the Henry Draper Catalogue) is the name of a Sun-like star 14.7 parsecs (47.9 light-years) from Earth in the constellation of Pegasus. It was the first Sun-like star to be found to have a planet orbiting it, a discovery that was announced in 1995. Flamsteed designations for stars are similar to Bayer designations, except that they use numbers instead of Greek letters. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... The Sun (or Sol) is the star at the center of our Solar system. ... The parsec (symbol pc) is a unit of length used in astronomy. ... A light year (or light-year), abbreviated ly, is the distance light travels in one year: about 9. ... Earth, also known as Terra, and Tellus mostly in the 19th century, is the third-closest planet to the Sun. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Pegasus is a northern constellation, named after the mythological Pegasus. ... The Sun (or Sol) is the star at the center of our Solar system. ... A planet is generally considered to be a relatively large mass of accreted matter in orbit around a star that is not a star itself. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... 1995 (MCMXCV) was a common year starting on Sunday of the Gregorian calendar. ...

The red circle shows the location of 51 Pegasi (R.A. 22h 57m 27s Dec. +20° 46' 05") in Pegasus

The exoplanet's discovery was announced on October 6, 1995 by Michael Mayor and Didier Queloz in Nature, volume 378, page 355. The discovery was made with the radial velocity method at the Observatoire de Genève. Wikipedia does not have an article with this exact name. ... Infrared image of the star GQ Lupi (A) orbited by a planet (b) at a distance of approximately 20 times the distance between Jupiter and our Sun. ... October 6 is the 279th day of the year (280th in Leap years). ... 1995 (MCMXCV) was a common year starting on Sunday of the Gregorian calendar. ... Michel Mayor (born 12 January 1942) is a professor at the Department of Astronomy at the University of Geneva. ... Didier Queloz, born 23 February 1966, is a Geneva-based astronomer with a prolific record in finding extrasolar planets. ... Nature is one of the oldest and most reputable scientific journals, first published on 4 November 1869. ... Sound waves emanating from an ambulance moving to the right. ...

The star

The star itself is of apparent magnitude 5.49, and so is visible from the Earth with binoculars, or with the naked eye by those with good vision in very dark sky conditions. 51 Pegasi is a yellow dwarf star estimated to be 7.5 billion years old, somewhat older than the Sun, 4% more massive, with more metal content and running low in hydrogen. Its spectral type is G2.5V. The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... U.S. Navy binoculars Binoculars Binocular telescopes or binoculars are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, one to be viewed through each of the users eyes. ... Yellow is a color with a wavelength 565-590 nanometers. ... Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... The Sun (or Sol) is the star at the center of our Solar system. ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily forms ions (cations) and has metallic bonds, and metals are sometimes described as a lattice of positive ions (cations) in a cloud of electrons. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ...

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.^[1]

The planet 51 Pegasi b

The name of the exoplanet is '51 Pegasi b' (see the article for more detailed information); the 'b' is used to indicate that it 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 temperatures around 1000 Celsius, and is about half the mass of Jupiter. At the time, this close distance was not compatible with theories of planet formation and resulted in discussions of orbital migration. 51 Pegasi b (informal name Bellerophon) is the first planet discovered around a sun-like star outside of the solar system. ... The degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701–1744), who first proposed a similar system in 1742. ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... An artists concept of a protoplanetary disk. ...

References

1. ^  Sallie Baliunas, Dmitry Sokoloff, and Willie Soon (1996 February 1). Magnetic Field and Rotation in Lower Main-Sequence Stars: An Empirical Time-Dependent Magnetic Bode's Relation?. THE ASTROPHYSICAL JOURNAL 457 (Number 2, Part 2): L99–L102.
2. Magnetic Field and Rotation in Lower Main-Sequence Stars. THE ASTROPHYSICAL JOURNAL. URL accessed on March 10, 2005. (lists rotational periods for 112 stars)