Arjuna Castrillon has defended her doctoral dissertation on the physics of planetary nebulae

This work addresses several topics in the study of the episodic jets (or bullets) ejected by the central source of a planetary nebula (PN). The presence of collimated bipolar outflows and point-symmetric morphologies are commonly observed in PNe, but the underlying physical mechanism is not fully understood. To address this problem, we have focused on the determination of the observational properties of Fast Low Ionization Emission Regions [FLIERs] and Low Ionization Structures [LIS] in PNe.
We have analyzed the morphology of a sample of selected PNe by means of anisotropic wavelet analysis applied to Hubble Space Telescope images. From this analysis, the spatial distribution of FLIERs/LIS and their characteristic sizes are determined.
We have obtained spectroscopic data with a 2-dimensional coverage of several PNe of our sample. With these data, we mapped the physical conditions, excitation, and ionization structure of the observed bow shock-like structures (FLIERs) which provide the effect of the photoionizing heating from the central star on shocked regions associated with bipolar jets (i.e, “irradiated shocks").