Global collapses and expansions in star-forming clouds

摘要: Spectral observations of star-forming molecular clouds sometimes reveal distinct red asymmetric double-peaked line profiles with weaker blue peaks and stronger peaks. For some clouds, transitions coexist those (i.e. peaks) in spatially resolved spectral from different lines sight, whereas for others dominate. Blue are usually interpreted as signals central core collapses, remain unexplained. In this paper, we advance a spherically symmetric self-similar hydrodynamic model framework envelope expansions collapses (EECCs) general poly-tropic gas cloud under self-gravity. Based on such EECC models, perform tracer profile calculations using the publicly available RATRAN code spectroscopic signatures profiles. The observation cores indicates that processes probably essential star formation. Using spatial distributions, explore various several molecules settings dynamic models without shocks.