Expanding shells in low and high density environments |
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Authors: | Jan Palou? Soňa Ehlerová Richard Wüunsch |
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Institution: | (1) Astronomical Institute, Academy of Sciences of the Czech Republic Boční II 1401, 141 31 Prague 4, Czech Republic |
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Abstract: | The gravitational instability of expanding shells evolving in a homogeneous and static medium is discussed. In the low density
environment (n = 1 cm-3), the fragmentation starts in shells with diameters of a few 100 pc and fragment masses are in the range of 5 × 103 - 106
M
⊙. In the high density environment (n = 105 - 107 cm-3), shells fragment at diameters of
pc producing clumps of stellar masses. The mass spectrum in both environments is approximated by a power law dN/dm ∼ m
-2.3. This is close to the slope of the stellar IMF. To reproduce the observed mass spectrum of clouds (the spectral index close
to ∼ -2.0) we have to assume, that the cloud formation time is independent of the cloud size, similarly to the Jeans unstable
medium.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | Stars: formation ISM: bubbles Galaxies: ISM |
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