The Dynamics of Dense Cores in the Perseus Molecular Cloud II: The Relationship Between Dense Cores and the Cloud

TL;DR

This study examines the kinematic relationship between dense cores and their larger molecular cloud environment in Perseus, providing observational constraints for star formation models.

Contribution

It offers detailed measurements of dense core motions relative to the surrounding gas, linking small-scale core dynamics to large-scale cloud turbulence.

Findings

Dense cores move slowly relative to 13CO gas.

Core-to-core velocity dispersion is about half of the total cloud dispersion.

Large-scale velocity gradients account for half of the velocity dispersion.

Abstract

We utilize the extensive datasets available for the Perseus molecular cloud to analyze the relationship between the kinematics of small-scale dense cores and the larger structures in which they are embedded. The kinematic measures presented here can be used in conjunction with those discussed in our previous work as strong observational constraints that numerical simulations (or analytic models) of star formation should match. We find that dense cores have small motions with respect to the 13CO gas, about one third of the 13CO velocity dispersion along the same line of sight. Within each extinction region, the core-to-core velocity dispersion is about half of the total (13CO) velocity dispersion seen in the region. Large-scale velocity gradients account for roughly half of the total velocity dispersion in each region, similar to what is predicted from large-scale turbulent modes following a power spectrum of P(k) ~ k^{-4}.