The star-forming content of the W3 giant molecular cloud

TL;DR

This study surveys the W3 giant molecular cloud in the 850-micron continuum, revealing how feedback from nearby stellar activity influences the distribution and mass of dense star-forming clumps, with implications for triggered star formation models.

Contribution

It provides the first detailed submillimeter survey of W3's dense clumps and analyzes how feedback affects their mass distribution and fraction of total gas mass.

Findings

Feedback increases dense gas mass fraction from 5-13% to 25-37%.

Clump mass distribution shows complex structure, not a simple power law.

No significant difference in high-mass end slope between affected and unaffected regions.

Abstract

We have surveyed a ~0.9-square-degree area of the W3 giant molecular cloud and star-forming region in the 850-micron continuum, using the SCUBA bolometer array on the James Clerk Maxwell Telescope. A complete sample of 316 dense clumps was detected with a mass range from around 13 to 2500 Msun. Part of the W3 GMC is subject to an interaction with the HII region and fast stellar winds generated by the nearby W4 OB association. We find that the fraction of total gas mass in dense, 850-micron traced structures is significantly altered by this interaction, being around 5% to 13% in the undisturbed cloud but ~25 - 37% in the feedback-affected region. The mass distribution in the detected clump sample depends somewhat on assumptions of dust temperature and is not a simple, single power law but contains significant structure at intermediate masses. This structure is likely to be due to crowding of sources near or below the spatial resolution of the observations. There is little evidence of any difference between the index of the high-mass end of the clump mass function in the compressed region and in the unaffected cloud. The consequences of these results are discussed in terms of current models of triggered star formation.