翻訳と辞書 Words near each other ・ Distichlis palmeri ・ Distichlis spicata ・ Distichoceras ・ Distichochlamys ・ Distichodontidae ・ Distichodus ・ Distance geometry problem ・ Distance Learning and Telemedicine Grant and Loan Program ・ Distance line ・ Distance matrices in phylogeny ・ Distance matrix ・ Distance measures (cosmology) ・ Distance measuring equipment ・ Distance medley relay ・ Distance model ・ Distance modulus ・ Distance of closest approach of ellipses and ellipsoids ・ Distance Only Makes the Heart Grow Fonder ・ Distance oracle ・ Distance sampling ・ Distance stars ・ Distance State University ・ Distance transform ・ Distance Vector Multicast Routing Protocol ・ Distance-bounding protocol ・ Distance-hereditary graph ・ Distance-regular graph ・ Distance-transitive graph ・ Distance-vector routing protocol ・ Distanced from Reality 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 Distance modulus ： ウィキペディア英語版 Distance modulus The distance modulus is a way of expressing distances that is often used in astronomy. ==Definition== The distance modulus $\backslash mu=m-M$ is the difference between the apparent magnitude $m$ (ideally, corrected from the effects of interstellar absorption) and the absolute magnitude $M$ of an astronomical object. It is related to the distance $d$ in parsecs by: :$\backslash log\_(d)\; =\; 1\; +\; \backslash frac$ :$\backslash mu=5\backslash log\_(d)-5$ This definition is convenient because the observed brightness of a light source is related to its distance by the inverse square law (a source twice as far away appears one quarter as bright) and because brightnesses are usually expressed not directly, but in magnitudes. Absolute magnitude $M$ is defined as the apparent magnitude of an object when seen at a distance of 10 parsecs. Suppose a light source has luminosity L(d) when observed from a distance of $d$ parsecs, and luminosity L(10) when observed from a distance of 10 parsecs. The inverse-square law is then written like: :$L(d)\; =\; \backslash frac)^2\}$ The magnitudes and luminosities are related by: :$m\; =\; -2.5\; \backslash log\_L(d)$ :$M\; =\; -2.5\; \backslash log\_L(10)$ Substituting and rearranging, we get: :$m\; -\; M\; =\; 5\; \backslash log\_(d)\; -\; 5\; =\; \backslash mu$ which means that the apparent magnitude is the absolute magnitude plus the distance modulus. Isolating $d$ from the equation $5\; \backslash log\_(d)\; -\; 5\; =\; \backslash mu$, we find that the distance (or, the luminosity distance) in parsecs is given by :$d\; =\; 10^+1\}$ The uncertainty in the distance in parsecs (δd) can be computed from the uncertainty in the distance modulus (δμ) using :$\backslash delta\; d\; =\; 0.2\; \backslash ln(10)\; 10^\; \backslash delta\backslash mu\; =\; 0.461\; d\; \backslash \; \backslash delta\backslash mu$ which is derived using standard error analysis. 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「Distance modulus」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.