The Mass-Size Relation from Clouds to Cores. I. A new Probe of Structure in Molecular Clouds

TL;DR

This paper introduces a new contour-based analysis method to measure the mass and size of molecular cloud fragments across a wide range of scales, providing insights into cloud structure and density gradients.

Contribution

The paper presents a novel scale-independent technique for analyzing molecular cloud structure, enabling comprehensive multi-scale mass-size measurements from cores to entire clouds.

Findings

Effective multi-scale analysis of Perseus Cloud data.

Derived mass-size law slopes constraining cloud density gradients.

Method applicable to diverse cloud data sets.

Abstract

We 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 < r / pc < 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 towards 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 constitutes 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.