An Observed Lack of Substructure in Starless Cores II: Super-Jeans Cores

TL;DR

This study observes dense cores in molecular clouds, finding that starless cores with super-Jeans masses lack substructure and are supported by non-thermal processes, challenging some collapse models.

Contribution

It provides observational evidence that starless super-Jeans cores lack substructure and are supported by non-thermal mechanisms, informing star formation theories.

Findings

Starless super-Jeans cores show flat density profiles.

Most cores lack detectable substructure or protostellar activity.

Non-thermal support may prevent collapse despite super-Jeans mass.

Abstract

We present SMA and CARMA continuum and spectral line observations of five dense cores located in the Perseus and Ophiuchus molecular clouds whose masses exceed their thermal Jeans masses. Three of these cores have previously been identified as being starless and two have been classified as being possibly protostellar. We find that one core is certainly protostellar. The other four cores, however, are starless and undetected in both C18O (2-1) and 1.3mm continuum emission. These four starless cores have flat density profiles out to at least 0.006 pc, which is typical for starless cores in general. Density profiles predicted by some collapse models, especially in the early stages of infall, are consistent with our observations. Archival data reveal that these starless cores have significant non-thermal support against collapse, although they may still be unstable.