New high-resolution observations of circumstellar environments are beginning to provide a wealth of detail about the nature of the physical processes occurring in stellar envelopes. These observations dramatically demonstrate that both axisymmetric and clumpy structures are ubiquitous, occurring in a diverse range of astrophysical systems, such as young stellar objects, outflows from highly evolved stars, and the explosive eruptions seen, for example, in novae, and supernovae. However to fulfill the promise of using these data to uncover the underlying physical mechanisms governing these phenomena, adequate theoretical techniques must be developed for investigating the transfer of radiation through matter with complex geometries. In this research 2- and 3-dimensional Monte Carlo simulations of the radiation transfer in these environments will be carried out. The geometries investigated primarily are the axisymmetric, disk-like structures produced around young stellar objects, highly evolved objects, and rotating stellar winds. Additional studies will investigate asymmetries in these environments, such as the clumpy winds of hot stars and spiral density waves in circumstellar disks.
Broader Impact. This work supports both a post-doctoral researcher and a graduate student, and hence directly contributes to the training of future researchers. In addition to graduate students, the principle investigator regularly works with undergraduates and exchange students leading to on-going collaborations with researchers in Brazil. To help enrich the local community, public lectures on this research are given, as well as teacher training workshops to K-12 teachers to help train the teachers in the practical use of hands-on activities for their classroom. Finally, this research is developing new parallel computing algorithms, which ultimately will benefit other researchers interested in multi-dimensional radiation transfer.
