Dynamics of a Collapsing Protostar

Citation

Larson, Richard Bondo (1968) Dynamics of a Collapsing Protostar. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/B8XQ-F688. https://resolver.caltech.edu/CaltechETD:etd-04302008-143923

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Numerical calculations of the dynamics of a spherically symmetric collapsing protostar have been made for various assumed initial conditions. In all cases the collapse is found to be extremely nonhomologous, the density distribution becoming more and more sharply peaked at the center as the collapse proceeds. As a result, a very small part of the cloud's mass at the center reaches stellar densities and temperatures and stops collapsing before most of the cloud has had time to collapse very far. The central stellar core thus formed subsequently grows in mass as the surrounding material falls into it, finally becoming an ordinary star when all of the original protostellar material has been accreted. During most of this time the forming star is completely obscured by the dust in the infalling cloud, the absorbed radiation reappearing in the infrared as thermal emission from the dust grains. For M = [...] the resulting star is almost a conventional Hayashi pre-main sequence model, but it appears quite low on the Hayashi track, at about [...]. For masses greater than about 2 or […] the convective Hayashi phase does not exist at all. The emitted spectrum of a protostar has been calculated from a simple approximation for the radiative transfer problem in the infalling cloud, and the results have been compared with some observations which may be relevant. It appears that some observations of infrared objects and some properties of T Tauri stars may be explainable from our results.

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