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Fast Low-Ionization Emission Region
Fast Low-Ionization Emission Region, or FLIER, is the name for volumes of gas with low ionization near the symmetry axis of many planetary nebulae. Red in color, they bolt out from planetary nebulae, clouds of ejected material from sunlike, old stars in the process of dying and exploding, at supersonic speeds. The Blinking Planetary features a set of FLIERs squirting horizontally from the nebula.〔Terzian, Yervant〕 Their outflow speeds are significantly higher than the nebulae in which they are embedded, and their ionizations are much lower. FLIERs' high speeds suggest ages much younger than their parent nebulae, and their low ionizations indicate that the ultraviolet radiation that ionizes the gas around them does not penetrate into the FLIERs.
A picture of the Blinking Planetary nebula was taken by the Hubble on 27 January 1996, and the estimated distance from the telescope to the nebula is about 0.7 kiloparsecs or 2,200 light-years. Previously, nebulae and their FLIERs could be seen from ground-based telescopes with limited clarity. The Hubble Space Telescope's Blinking Planetary image credit goes to astronomers Bruce Balick of the University of Washington; Jason Alexander, University of Washington; Arsen Hajian, U.S. Naval Observatory, Washington, D.C.; Mario Perinotto, University of Florence (Italy); Patrizio Patriarchi, Arcetri Observatory (Italy); and Cornell's Terzian, who used a special instrument with the Hubble Telescope known as WFPC2 (pronounced "wiffpick two"). Object NGC 7009, which also shows very prominent FLIERs, nicknamed the Saturn Nebula, was observed by the Hubble Space Telescope on 28 April 1996, and is one of the images released. Astronomers believe the distance from here to the Saturn Nebula is 0.42 kiloparsecs or 1,400 light-years.
==References==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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