English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

In order to understand the collapse dynamics of observed low-mass starlesscores, we revise the conventional stability condition of hydrostaticBonnor-Ebert spheres to take internal motions into account. Because observedstarless cores resemble Bonnor-Ebert density structures, the stability anddynamics of the starless cores are frequently analyzed by comparing to theconventional stability condition of a hydrostatic Bonnor-Ebert sphere. However,starless cores are not hydrostatic but have observed internal motions. In thisstudy, we take gaseous spheres with a homologous internal velocity field andderive stability conditions of the spheres utilizing a virial analysis. Wepropose two limiting models of spontaneous gravitational collapse: the collapseof critical Bonnor-Ebert spheres and uniform density spheres. The collapse ofthese two limiting models are intended to provide the lower and the upperlimits, respectively, of the infall speeds for a given density structure. Theresults of our study suggest that the stability condition sensitively dependson internal motions. A homologous inward motion with a transonic speed canreduce the critical size compared to the static Bonnor-Ebert sphere by morethan a factor of two. As an application of the two limiting models ofspontaneous gravitational collapse, we compare the density structures andinfall speeds of the observed starless cores L63, L1544, L1689B, and L694-2 tothe two limiting models. L1689B and L694-2 seem to have been perturbed toresult in faster infall motions than for spontaneous gravitational collapse.

On the internal dynamics of starless cores: stability of starless cores with internal motions and collapse dynamics