distance modulus

distance modulus

(moj -ŭ-lŭs) The difference between the apparent magnitude, m , and the absolute magnitude, M , of a star and therefore a measure of distance (see magnitude):

m – M = 5 log(d /10) = 5 logd – 5

where d is the distance in parsecs. Distance modulus is used to determine the distances of stars and stellar clusters. It is corrected for interstellar extinction by an additional term (see magnitude).

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

distance modulus

[′dis·təns ‚mäj·ə·ləs]

(astronomy)

modulus of distance

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Distance Modulus

 

in astronomy, the difference between the apparent (m) and absolute (M) magnitudes of a celestial body. This quantity is used to describe distances to stars and stellar systems. Whereas M depends only on the intrinsic luminosity of a star, m depends also on the distance r (in parsecs) to the star, that is, m – M = 5 log r — 5.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.