The Bias of Molecular Clump Identification Programs: the Example of the Carina Molecular Clouds

Abstract

A large scale ¹²CO J = 1 → 0 molecular line map of the Carina molecular cloud complex was obtained with the Mopra radio telescope in order to investigate its spatial and kinematic structure. The data show a complex velocity structure in two distinct cloud regions — the Northern and Southern Carina clouds. Two different clump identification methods (GAUSSCLUMPS and CLUMPFIND) were applied to the data. Though both algorithms find a similar clump mass spectral index (1.95 and 1.8, respectively), the properties of the clumps (mass, size, virial equilibrium) differ significantly. We discuss possible explanations for this discrepancy and question the validity of the Larson relations which could be an artifact of the limited spatial resolution and dynamic range of the observations.