Dense core evolutions induced by shock triggering and turbulent dissipation

External shock triggering and internal turbulence play major role for the condensation of the ISM and star formation. Some evidences of shock triggering by non-isotropic compression are seen in the cloud morphologies and associated active cluster formation such as the ρ Oph and Cha I clouds. Surveys for C¹⁸O dense cores have shown that internal turbulence dominates the core dynamics and regulates star formation activity (Tachihara et al. 2002).