翻訳と辞書 Words near each other ・ Photocyte ・ Photodarkening ・ Photodegradation ・ Photodermatitis ・ Photodermatology, Photoimmunology and Photomedicine ・ Photodermatosis ・ Photodetection ・ Photodetector ・ Photodex ・ Photodiode ・ PhotoDisc ・ Photodisintegration ・ Photodisintegration hypernovae ・ Photodisruption ・ Photodissociation ・ Photodissociation region ・ PhotoDNA ・ Photodotis ・ Photodotis abachausi ・ Photodotis adornata ・ Photodotis palens ・ Photodotis pellochroa ・ Photodotis photinopa ・ Photodotis prochalina ・ Photodotis spilodoma ・ PhotoDVD ・ Photodynamic therapy ・ Photoelastic modulator ・ Photoelasticity ・ Photoelectric effect Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Photodissociation region ： ウィキペディア英語版 Photodissociation region Photodissociation regions (or photon-dominated regions, or PDRs) are predominantly neutral regions of the interstellar medium in which far ultraviolet photons strongly influence the gas chemistry and act as the most important source of heat. They occur in any region of interstellar gas that is dense and cold enough to remain neutral, but that has too low a column density to prevent the penetration of far-UV photons from distant, massive stars. A typical and well-studied example is the gas at the boundary of a giant molecular cloud.〔 PDRs are also associated with HII regions, reflection nebulae, active galactic nuclei, and Planetary nebulae.〔〕 All the atomic gas and most of the molecular gas in the galaxy is found in PDRs. ==History== The study of photodissociation regions began from early observations of the star-forming regions Orion A and M17 which showed neutral areas bright in infrared radiation lying outside ionised HII regions.〔 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「Photodissociation region」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.