Two Mass Distributions in the L 1641 Molecular Clouds: The Herschel connection of Dense Cores and Filaments in Orion A

TL;DR

This study uses Herschel data to analyze the distribution of dense cores and filaments in Orion A's L1641 clouds, revealing distinct mass distributions for sources on and off filaments and their implications for star formation.

Contribution

It identifies and compares the mass distributions of dense cores on and off filaments, highlighting the role of filaments in star formation in Orion A.

Findings

Most pre-stellar sources are on filaments (71%).

Mass distribution on filaments peaks at 4 solar masses.

Off-filament sources have a peak at 0.8 solar masses.

Abstract

We present the Herschel Gould Belt survey maps of the L1641 molecular clouds in Orion A. We extracted both the filaments and dense cores in the region. We identified which of dense sources are proto- or pre-stellar, and studied their association with the identified filaments. We find that although most (71%) of the pre-stellar sources are located on filaments there is still a significant fraction of sources not associated with such structures. We find that these two populations (on and off the identified filaments) have distinctly different mass distributions. The mass distribution of the sources on the filaments is found to peak at 4 Solar masses and drives the shape of the CMF at higher masses, which we fit with a power law of the form dN/dlogM \propto M^{-1.4+/-0.4}. The mass distribution of the sources off the filaments, on the other hand, peaks at 0.8 Solar masses and leads to a flattening of the CMF at masses lower than ~4 Solar masses. We postulate that this difference between the mass distributions is due to the higher proportion of gas that is available in the filaments, rather than in the diffuse cloud.