On the internal dynamics of the starless core L694-2

Abstract

In order to understand the internal dynamics of starless cores, we take L694-2 as an example of starless cores and investigate its internal dynamics by comparing observed data of L694-2 to our two hydrodynamical simulations, which involve the gravitational collapse of marginally unstable Bonnor-Ebert and uniform cores in a quiescent region. From the comparisons, we find that the density structures of the models agree well with the observed density distribution of L694-2, but the velocity fields and HCN line profiles of the models differ from the observed ones. From the differences in the velocity fields and the HCN line profiles, we have reached the following conclusions on the internal dynamics of L694-2. First, L694-2 has different internal dynamics from the gravitational collapse of the marginally unstable Bonnor-Ebert core. Second, L694-2 has an infall speed faster than any other core that undergoes the gravitational collapse with a Bonnor-Ebert-like density structure in a quiescent region. Third, L694-2 has almost no motion at its surface. From further simulations, in which cores are perturbed by supersonic shocks and affected by an expanding inter-core medium, the differences in the HCN line profiles could be reduced considerably. © 2011. The American Astronomical Society. All rights reserved.