2012/Nov/13

Isotopic Fractionation in Primitive Materials: Quantifying the Contribution
of Interstellar Chemistry

Dr Steven Charnley (NASA/GSFC)

Abstract
========
Anomalously fractionated isotopic material is found in many primitive Solar
System objects, such as meteorites and comets. It is thought, in some cases,
to trace interstellar matter that was incorporated into the Solar Nebula
without undergoing significant processing. We will present the results of
models of the nitrogen, oxygen, and carbon fractionation chemistry in dense
molecular clouds, particularly in cores where substantial freeze-out of
molecules on to dust has occurred. The range of fractionation ratios
expected in different interstellar molecules will be discussed and compared
to the ratios measured in molecular clouds, comets and meteoritic material.

   We will also present results form recent observations and modeling of
interstellar anion chemistry.These studies make several predictions that can
be tested in the near future by high-resolution molecular line observations
with ALMA.