Shocked Similarity Collapses and Flows in Star Formation Processes

We propose self-similar shocked flow models for certain dynamical evolution phases of young stellar objects (YSOs), ‘champagne flows’ of H II regions surrounding OB stars and shaping processes of planetary nebulae (PNe). We analyze an isothermal fluid of spherical symmetry and construct families of similarity shocked flow solutions featured by: 1. either a core expansion with a finite central density or a core accretion at constant rate with a density scaling ∝ r−3/2; 2. a shock moving outward at a constant speed; 3. a preshock gas approaching a constant speed at large r with a density scaling ∝ r−2. In addition to testing numerical codes, our models can accommodate diverse shocked flows with or without a core collapse or outflow and an envelope expansion or contraction. As an application, we introduce our model analysis to observations of Bok globule B335. Subject headings: HII regions – HD – ISM: clouds – shock waves – stars: formation: B335 – winds, outflows