Kauffmann, JensPillai, ThusharaShetty, RahulMyers, Philip C.Goodman, Alyssa2010-06-142010Kauffmann, Jens, Thushara Pillai, Rahul Shetty, Philip C. Myers, and Alyssa A. Goodman. 2010. The mass-size relation from clouds to cores. I. A new probe of structure in molecular clouds. The Astrophysical Journal 712(2): 1137-1146.0004-637Xhttp://nrs.harvard.edu/urn-3:HUL.InstRepos:4214907We use a new contour-based map analysis technique to measure the mass and size of molecular cloud fragments continuously over a wide range of spatial scales \((0.05 \leq r/pc \leq 10)\), i.e., from the scale of dense cores to those of entire clouds. The present paper presents the method via a detailed exploration of the Perseus molecular cloud. Dust extinction and emission data are combined to yield reliable scale-dependent measurements of mass. This scale-independent analysis approach is useful for several reasons. First, it provides a more comprehensive characterization of a map (i.e., not biased toward a particular spatial scale). Such a lack of bias is extremely useful for the joint analysis of many data sets taken with different spatial resolution. This includes comparisons between different cloud complexes. Second, the multi-scale mass-size data constitute a unique resource to derive slopes of mass-size laws (via power-law fits). Such slopes provide singular constraints on large-scale density gradients in clouds.en-USISM: cloudsmethods: data analysisstars: formationJournal Article2010-06-1410.1088/0004-637X/712/2/1137