1206.3028 (Liton Majumdar et al.)

Hydro-chemical study of the evolution of interstellar pre-biotic molecules during the collapse of molecular clouds    [PDF]

Liton Majumdar, Ankan Das, Sandip K. Chakrabarti, Sonali Chakrabarti

One of the stumbling blocks for studying the evolution of interstellar molecules is the lack of adequate knowledge of the rate coefficients of various reactions which take place in the ISM & molecular clouds. In order to obtain accurate final compositions in the ISM, we find out the rate coefficients for the formation of some of the most important interstellar pre-biotic molecules by using quantum chemical theory. We use these rates inside our hydro-chemical model to find out the chemical evolution and the final abundances of the pre-biotic species during the collapsing phase of a proto-star. We find that a significant amount of various pre-biotic molecules could be produced during the collapsing phase of a proto-star. We study extensively the formation of these molecules via successive neutral-neutral(NN) and radical-radical(RR)/radical-molecular(RM) reactions. We present the time evolution of the chemical species with an emphasis on how the production of these molecules varies with the depth of a cloud. We compare the formation of adenine in the interstellar space using our rate-coefficients and using those obtained from the existing theoretical models. Formation routes of the pre-biotic molecules are found to be highly dependent on the abundances of the reactive species and the rate coefficients involved in the reactions. Presence of grains strongly affect the abundances of the gas phase species. We also carry out a comparative study between different pathways available for the synthesis of adenine, alanine, glycine and other molecules considered in our network.

View original: http://arxiv.org/abs/1206.3028