Abstract
The contraction processes of metal-free molecular clouds of starlike mass (or cloud cores) are investigated. We calculate radiative transfer of the H2 lines and examine quasi-static contraction with radiative cooling. Comparing two time-scales, the free-fall time tff and the time-scale of quasi-static contraction tqsc (∼ tcool, the cooling time) of these cores, we find that the ratio of the two time-scales tff/tqsc, 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 tff ∼ tqsc at the fragmentation epoch, they collapse dynamically in the free-fall time-scale. This efficiency of cooling is unique to line cooling.
Original language | English |
---|---|
Pages (from-to) | 747-761 |
Number of pages | 15 |
Journal | Progress of Theoretical Physics |
Volume | 99 |
Issue number | 5 |
DOIs | |
Publication status | Published - 1998 May |
Externally published | Yes |
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)