Isotopic studies of presolar grains; stellar nucleosynthesis in different types of stars; formation of presolar grains in stellar environments; isotopic anomalies in meteorites and their connections to those different types of presolar grains.
B.E., Environmental Science, University of Science and Technology of China, 2009 Ph.D., Cosmochemistry, University of Chicago, 2014
Nan Liu is interested in isotope studies of presolar grains (left image), which are condensed dusts during stellar winds and/or explosions that were ejected to the interstellar medium, and became part of the proto-solar cloud from which the Sun formed. Isotopic composition of such grains allows studies of nucleosynthesis in their parent stars at a level of detail that is unavailable to spectroscopic observation.
For her Ph.D. research, she focused on isotope analysis of s (slow neutron capture)-process elements in single presolar SiC grains (right image) using the CHARISMA instrument by Resonance Ionization Mass Spectrometry (RIMS) at Argonne National Laboratory. Such in situ isotope analysis of heavy elements in mainstream type grains from asymptotic giant branch (AGB) stars allowed derivation of new constraints on the “13C-pocket” that is the main neutron source for the s-process in AGB stars.
At DTM, she plans to extend her research to isotope studies of other types of presolar grains, which came from various types of stars and can be used to study other nucleosynthetic processes in their parent stars. These grains are rare and need extensive search using the NanoSIMS instrument for isotopic compositions of light elements (e.g., C and Si). In addition to constrain different nucleosynthetic processes in stars, she is also interested in exploring the connection between the origin of the solar system (isotopic anomalies found in primitive meteorites) and isotopic compositions of the presolar grains.