Star formation at very low metallicity. I: Chemistry and cooling at low densities - AstrophysicsReportar como inadecuado




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Abstract: We present a simplified chemical and thermal model designed to allowcomputationally efficient study of the thermal evolution of metal-poor gaswithin large numerical simulations. Our main simplification is the neglect ofthe molecular chemistry of the heavy elements. The only molecular chemistryretained within the model is the formation and destruction of molecularhydrogen. Despite this major simplification, the model allows for accuratetreatment of the thermal evolution of the gas within a large volume ofparameter space. It is valid for temperatures 50 < T < 10000 K andmetallicities 0 < Z < 0.1 Z solar. In gas with a metallicity Z = 0.1 Z solar,and in the absence of an incident ultraviolet radiation field, it is valid forhydrogen number densities n H < 500 - t char cm^-3, where t char is the size inMyr of the characteristic physical timescale of interest in the problem. If Z<< 0.1 Z solar, or if a strong ultraviolet radiation field is present, then themodel remains accurate up to significantly higher densities. We also discusssome possible applications of this model.



Autor: S. C. O. Glover, A.-K. Jappsen

Fuente: https://arxiv.org/







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