Shocked Self-similar Collapses and Flows in Star Formation Processes

We propose self-similar shocked flow models for certain dynamical evolutionphases of young stellar objects (YSOs), `champagne flows' of H {\sevenrm II}regions surrounding OB stars and shaping processes of planetary nebulae (PNe).We analyze an isothermal fluid of spherical symmetry and construct families ofsimilarity shocked flow solutions featured by: 1. either a core expansion witha finite central density or a core accretion at constant rate with a densityscaling $\propto r^{-3/2}$; 2. a shock moving outward at a constant speed; 3. apreshock gas approaching a constant speed at large $r$ with a density scaling$\propto r^{-2}$. In addition to testing numerical codes, our models canaccommodate diverse shocked flows with or without a core collapse or outflowand an envelope expansion or contraction. As an application, we introduce ourmodel analysis to observations of Bok globule B335.Comment: ApJL accepte