翻訳と辞書 Words near each other ・ R v Clarkson ・ R v Clay ・ R v Cogdon ・ R v Collins ・ R v Collins (1987) ・ R Canis Majoris ・ R Canum Venaticorum ・ R Carinae ・ R Cassiopeiae ・ R Centauri ・ R City Mall ・ R class ・ R Commander ・ R Coronae Australis ・ R Coronae Borealis ・ R Coronae Borealis variable ・ R Corvi ・ R Crucis ・ R Cygni ・ R D Memorial High School, Naigaon ・ R D Rajpal public school ・ R Doradus ・ R Equulei ・ R Family Vacations ・ R Flourney, California ・ R Force ・ R Gandhi ・ R Geminorum ・ R gene ・ R Gopalakrishnan 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 R Coronae Borealis variable ： ウィキペディア英語版 R Coronae Borealis variable An R Coronae Borealis variable (abbreviated RCB, RCrB) is an eruptive variable star that varies in luminosity in two modes, one low amplitude pulsation (a few tenths of a magnitude), and one irregular unpredictably sudden fading by 1 to 9 magnitudes. The prototype star R Coronae Borealis was discovered by the English amateur astronomer Edward Pigott in 1795, who first observed the enigmatic fadings of the star. Since then, only about 100 RCB variables have been identified, making this class a very rare kind of star. The fading is caused by condensation of carbon to soot, making the star fade in visible light while measurements in infrared light exhibit no real luminosity decrease. R Coronae Borealis variables are typically supergiant stars in the spectral classes F and G (by convention called "yellow"), with typical C2 and CN molecular bands, characteristic of yellow supergiants. RCB star atmospheres do however lack hydrogen by an abundance of 1 part per 1,000 down to 1 part per 1,000,000 relative to helium and other chemical elements, while the universal abundance of hydrogen is about 3 to 1 relative to helium. ==Diversity== There is a considerable variation in spectrum between various RCB specimens. Most of the stars with known spectrum are either F to G class ("yellow") supergiants, or a comparatively cooler C-R type carbon star supergiant. Three of the stars are however of the "blue" B type, for example VZ Sagittarii. Four stars are unusually and inexplicably poor in iron absorption lines in the spectrum. The constant features are prominent Carbon lines, strong atmospheric Hydrogen deficiencies, and obviously the intermittent fadings. The DY Persei variables have been considered a sub-class of R CrB variable, although they are less luminous carbon-rich AGB stars and may be unrelated. 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「R Coronae Borealis variable」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.