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Evolution of Primordial Protostellar Clouds --- Quasi-Static Analysis ---

Kazuyuki Omukai·Ryoichi Nishi·Hideya Uehara·Hajime Susa
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Abstract

The contraction processes of metal-free molecular clouds of starlike mass (or cloud cores) are investigated. We calculate radiative transfer of the H_2 lines and examine quasi-static contraction with radiative cooling. Comparing two time-scales, the free-fall time t_ff and the time-scale of quasi-static contraction t_qsc (nearly equal to t_cool, the cooling time) of these cores, we find that the ratio of the two time-scales t_ff/t_qsc, i.e., the efficiency of cooling, becomes larger with contraction even under the existence of cold and opaque envelopes. In particular, for fragments of primordial filamentary clouds, for which t_ff is nearly equal to t_qsc at the fragmentation epoch, they collapse dynamically in the free-fall time-scale. This efficiency of cooling is unique to line cooling.

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Kazuyuki Omukai, Ryoichi Nishi, Hideya Uehara, Hajime Susa. 1998-09-18. Evolution of Primordial Protostellar Clouds --- Quasi-Static Analysis ---. https://doi.org/10.1143/ptp.99.747

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