0 Assigned ID: 827 ----- Attempting Submission 1 (Fri Mar 06 21:57:06 GMT 2020) ----- HST Phase I Proposal 827 successfully submitted. Receipt: # 827-1 ----- Attempting Submission 2 (Sat Mar 07 00:39:22 GMT 2020) ----- Type Ia supernovae (SNe Ia) have inspired and baffled observers throughout the documented history of their occurrences. Despite frequent observations and fervent studying throughout the past, the true origin of these highly luminous events is still a great mystery. While it is generally agreed upon that a SN Ia is a thermonuclear explosion of a carbon/oxygen white dwarf within a binary system, the precise progenitor systems and explosion mechanisms that generate these supernovae are not well known. A promising explosion mechanism that has recently come to the fore for a significant share of observed SNe Ia is the double detonation. This mechanism, while promising, has received little study via computation of its UV spectral characteristics. We propose to conduct a series of 2D simulations of double detonations in carbon/oxygen white dwarfs with a thin shell of helium, with progenitors varying in both mass and metallicity. Through comparison of the predicted UV spectra to those previously observed with HST, we aim to address the viability of the double detonation scenario and how metallicity affects observables in this model. The proposal team has already demonstrated the ability to compute double-detonation model simulations, including radiative transfer producing spectra for comparison to observations (Townsley et al. 2019). We are the only group currently with published multi-dimensional thin-He-shell double detonation simulations. Co-I Boos is the Ph.D. student who is expected to perform this work and has already performed 8 full simulations of double detonations and is preparing a publication covering them. 2D radiative transfer for these simulations is currently being computed and has already been done for earlier trial work of his. As a result, Boos is well experienced with running the main proposed simulations in FLASH, post-processing this data with MESA to get ejecta abundance profiles, and preparing these for radiative transfer computations. Co-I Shen is performing the radiative transfer calculations using Sedona, and is funded under separate sources. Shen has extensive experince with simulations of Type Ia supernovae, including discovery of critical details of the nuclear kinetics necessary for the helium detonation phase. He has also authored many works on theoretical investigation of SN Ia with a variety of models. PI Townsley has performed simulations of Type Ia supernova and related explosions in many publications, including both the DDT and double-detonation mechanisms. The previous UV spectral work referenced in the proposal (Miles et al. 2016) was performed by a previous graduate student of Townsley along with other collaboratons. Townsley has also created and authored works on the methods used in these simulations with students and collaborators. Stellar Physics and Stellar Types 0 Regular false false false true false SUPPORTED