# A calculation of the mean age of interstellar dust particles

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 Title: A calculation of the mean age of interstellar dust particles Scowen, Paul Andrew Clayton, Donald D. Master of Science thesis This thesis aims to compute the mean age of interstellar dust particles using a sputtering and recycling model originally formulated by Liffman and Clayton. The ages of the particles are evaluated after a period of 6 $\times$ 10$\sp9$ years, deemed here to be the age of our Galaxy, when the Solar System formed. I find a correlation between resulting particle sizes and their mean age. The consequence of this correlation is that if interstellar particles can be sorted dynamically by size, then the conglomerations of these size populations as dust grains will be composed of matter that is of differing ages. This age variation in grains of differing sizes will produce isotopic variations, or anomalies, due to the time dependent nature of secondary versus primary nucleosynthesis. The most important example of such an observed anomaly is the 5% enrichment of $\sp{16}$O in inclusions of Al$\sb2$O$\sb3$ in meteorite structures relative to the abundance of $\sp{16}$O in the solar gas. (Abstract shortened with permission of author.) Scowen, Paul Andrew. (1989) "A calculation of the mean age of interstellar dust particles." Masters Thesis, Rice University. http://hdl.handle.net/1911/13392. http://hdl.handle.net/1911/13392 1989