Saturday. It seems like my brain is in overdrive. I should make good use of it. :)
1206.6492
Dispersal of molecular clouds by ionizing radiation
Walch et al
Feedback from massive stars key element in the evolution of molecular clouds; simulate them. (i) In the short term, the ionizing feedback is positive (SF faster in gas compressed by high pressure of ionized gas). In long term, it's negative (cloud dispersed)--triggered SF limited to a few percent of cloud's mass. (ii) Ionization fronts (IFs) of HII and outflowing gas boundary: For low fractal dimensions, initial cloud dominated by LSS, so neutral gas swept up for a few extended coherent shells. For high fractal dimensions, small scale structures quickly overrun by advancing IF, produce neutral pillars while ionized gas blows out through a large number of small holes between the pillars. (iii) Injection of bulk kinetic energy: expansion of HII region delivers rms velocity of 6 km/s, <0.1% of the total energy radiated by O7 star.
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