update, hopefully final -1443927737 Assigned ID: 2009 ----- Attempting Submission 1 (Fri Apr 09 16:33:27 GMT 2021) ----- HST Phase I Proposal 2009 successfully submitted. Receipt: # 2009-1 ----- Attempting Submission 2 (Fri Apr 09 21:20:38 GMT 2021) ----- Some accreting white dwarfs (WD) show near-sinusoidal light variations on hundreds of seconds, which, due to their periods and photosphereic origin, are attributed to asteroseismic non-radial oscillations within the star. Non-radial oscillations are sensitive to the star's interior mechanical and thermal structure, hence asteroseismology offers the potential to probe aspects of the structure such as mass, radius, temperature, core temperature, extent of various compositional layers, and rotation behavior along with the star's evolution history. These objects are also subject to dwarf nova outbursts, intermittent accretion events with recurrence times of order tens of years. The resulting heating of the outer layers can shift the oscillation periods in a way that is unique to each mode and may be used to identify the modes and learn about the interior. We propose to construct a full framework for detailed modeling of the non-radial standing wave oscillation modes of accreting white dwarfs. This will involve varying white dwarf parameters like mass, accretion rate, thickness of the accreted layer, spin, and others in order to be able to infer these parameters from comparing models to measurements. This is a novel and exciting direction of WD asteroseismology and will be broadly applicable to a wide variety of both previously performed and future HST measurements of these systems. PI Dean Townsley is the leading expert on theoretical modeling of whole-star seismology of accreting white dwarfs, having authored the authoritative papers on this topic over the last 15 years. Townsley's published research, with various collaborators, covers both the thermal state of accreting white dwarfs (essential for any seismological model) as well as seismology itself in both the non-rotating and rapidly rotating cases. (Please see citations including Townsley as an author in the main proposal text.) Townsley has also contributed essential aspects to the capability of MESA to simulate accretion with an accurate surface boundary condition. co-I Praphull Kumar is a graduate student working under PI Townsley. While still working on his first publication, he will have completed all of his coursework by the end of Spring 2021 and has been working on this project since Spring 2020. He has already passed his doctoral qualifying exams. He did both the MESA simulations and GYRE seismology computations for the figures shown in the proposal and thus is fully capapble of performing the proposed work. Stellar Physics and Stellar Types 0 Regular false false false true false SUPPORTED