Journal Article

Statistical comparison of clouds and star clusters

O. Lomax, A. P. Whitworth and A. Cartwright

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 412, issue 1, pages 627-633
Published in print March 2011 | ISSN: 0035-8711
Published online March 2011 | e-ISSN: 1365-2966 | DOI:
Statistical comparison of clouds and star clusters

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The extent to which the projected distribution of stars in a cluster is due to a large-scale radial gradient, and the extent to which it is due to fractal substructure, can be quantified – statistically – using the measure . Here is the normalized mean edge length of its minimum spanning tree (i.e. the shortest network of edges connecting all stars in the cluster) and is the correlation length (i.e. the normalized mean separation between all pairs of stars).

We show how can be indirectly applied to grey-scale images by decomposing the image into a distribution of points from which and can be calculated. This provides a powerful technique for comparing the distribution of dense gas in a molecular cloud with the distribution of the stars that condense out of it. We illustrate the application of this technique by comparing values from simulated clouds and star clusters.

Keywords: stars: evolution; stars: formation; ISM: structure

Journal Article.  3626 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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