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| EPoS Contribution |
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The formation of prestellar cores
Paul C. Clark ITA, ZAH, Universität Heidelberg, Heidelberg, Germany | |
| Understanding the formation of prestellar cores lies at the very heart of understanding the early phase of the star formation process. On the observational front, much progress has been made in terms of constraining the core properties and the environmental conditions in which they sit. However it is still difficult to compare these observations to the current zoo of star formation theories. The models tend to neglect two main process which are essential for making meaningful comparisons with the observational data. First they have a fairly poor prescription for the thermodynamics at the densities relevant for the formation of prestellar cores (i.e. n < 10^{5} cm^{-3}), and secondly they don't include the time-depenent chemistry that is required to help make synthetic maps of the cores and their environments. Our new numerical scheme is a first attempt to address these issues. We include the majority of the processes which are expected to dominate the heating and cooling balance in star-forming regions, such as: photoelectric heating from dust; Excitation and photo-dissocitaion of H2; H2 formation heating on dust grains; cosmic rays; gas-dust energy transfer; dust heating from ISRF; atomic and molecular line cooling; and an accurate treatment of the adiabatic index. We find that the core formation time and core lifetimes are at least twice as long as in the isothermal case. Much of this is due to the fact that line-cooling typically becomes inefficient before the gas can couple to the dust, and is unable to rid the gas of compressional heating. We also find that while the densities and temperatures of the gas-dust coupling transition are sensitive to metallicity, the Jean mass at which the transition occurs is less sensitive, at around 1 solar mass. | |
| Collaborators: S.C.O. Glover, ITA/ZAH, Germany R.S. Klessen, ITA/ZAH, Germany |
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