Shocked Self-similar Collapses and Flows in Star Formation Processes

Abstract

We propose self-similar shocked flow models for certain dynamical evolution phases of young stellar objects, champagne of H II regions surrounding OB stars, and shaping processes of planetary nebulae. We analyze an isothermal fluid of spherical symmetry and construct families of self-similar shocked flow solutions that feature (1) either a core expansion with a finite central density or a core accretion at a constant rate with a density scaling proportional to r-3/2 (a free-fall state); (2) a shock moving outward at a constant speed (a wind, a breeze, or an accretion flow); and (3) a preshock gas approaching a constant speed at large r with a density scaling proportional to r-2. In addition to testing numerical codes, our models can accommodate diverse shocked flows with or without a core collapse or outflow and with or without an envelope expansion or contraction. As an application, we introduce our model analysis to observations of Bok globule B335.