- Luminosity distance
Luminosity distance "DL" is defined in terms of the relationship between the
absolute magnitude "M" andapparent magnitude "m" of an astronomical object.:M = m - 5 (log_{10}{D_L} - 1)!,
which gives:
:D_L = 10^{frac{(m - M)}{5}+1}
where "DL" is measured in
parsec s. For nearby objects (say, in theMilky Way ) the luminosity distance gives a good approximation to the natural notion of distance inEuclidean space .For distant objects far beyond the
Milky Way , the relation is less clear, since the apparent magnitude is affected byspacetime curvature ,redshift , andtime dilation . Calculating the relation between the luminosity distance and, for example, redshift of an object requires taking all of these factors into account.ee also
*
Distance measures (cosmology)
*distance modulus External links
* [http://www.astro.ucla.edu/~wright/CosmoCalc.html Ned Wright's Javascript Cosmology Calculator]
* [http://icosmos.co.uk/ iCosmos: Cosmology Calculator (With Graph Generation )]
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