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Fomalhaut b is a confirmed, directly imaged〔 extrasolar object and candidate planet orbiting the A-type main-sequence star Fomalhaut, approximately 25 light-years away in the constellation of Piscis Austrinus. The object was initially announced in 2008 and confirmed as real in 2012 from images taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope and, according to calculations reported in January 2013, has a 1,700-year,〔 highly elliptical orbit. It has a periastron of 7.4 billion km (~50 AU) and an apastron of about 44 billion km (~300 AU). As of May 25, 2013 it is 110 AU from its parent star. The planet is one of those selected by the International Astronomical Union as part of their public process for giving proper names to exoplanets.〔(NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars ). IAU.org. 9 July 2014〕〔(NameExoWorlds ).〕 The process involves public nomination and voting for the new name, and the IAU plans to announce the new name in mid-November 2015.〔(NameExoWorlds ).〕 ==Summary== The nature of Fomalhaut b became unclear after its discovery. Fomalhaut b could be a conglomeration of rubble from a recent collision between comet-to-asteroid-sized bodies and not actually identify a planet.〔 Although this scenario is possible, the likelihood of observing such a collision at the location of Fomalhaut b is extremely low. Instead, Fomalhaut b is plausibly, even probably, a planet less than twice Jupiter's mass that is either enshrouded in a spherical cloud of dust from ongoing planetesimal collisions〔 or surrounded by a large circumplanetary ring system,〔 either of which are responsible for scattering the primary star's light and thus making Fomalhaut b visible. Fomalhaut b and three companions around HR 8799, whose discovery was announced simultaneously, were described as the first directly imaged extrasolar planets in that their emission was thought to originate at least in part from a planetary atmosphere. However, subsequent studies from the Spitzer Space Telescope and a reanalysis of the original HST data〔 instead suggest that Fomalhaut b's light is scattered starlight, not planet thermal emission. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fomalhaut b」の詳細全文を読む スポンサード リンク
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