0 Assigned ID: 241 ----- Attempting Submission 1 (Thu Mar 05 16:11:06 GMT 2020) ----- HST Phase I Proposal 241 successfully submitted. Receipt: # 241-1 ----- Attempting Submission 2 (Fri Mar 06 22:19:37 GMT 2020) ----- Highly irradiated brown dwarfs (BDs) provide essential tests to models of brown dwarf atmospheric physics. While only a handful have been discovered, BDs in ultra-short period orbits around white dwarfs (WDs) are a physically interesting and observationally favorable class of irradiated substellar objects, reaching equilibrium temperatures matching or exceeding their internal heat. Recently, HST Program 15947 was approved to execute the first survey of such objects. Currently, however, no self-consistent BD atmosphere models exist that take into account the extreme UV irradiation from a WD host. We propose to calculate the first grid of self-consistent atmosphere models and synthetic spectra for Program 15947's six targets to strengthen the theoretical expectations for how the atmosphere's of these informative objects behave under such extreme conditions. We will investigate the interplay between extreme irradiation and high internal heat, as well as the sensitivity of emergent spectra to intrinsic properties like the internal temperature, efficiency of heat transport, albedo, surface gravity, and metallicity. The grid will also enhance the interpretation of other existing HST datasets, including observations of two brown dwarfs around main-sequence stars and the large collections of hot Jupiter and isolated brown dwarf spectra. Future observations with JWST of these various classes of substellar object will also benefit from this investigation. Dr. Lothringer is an expert in atmosphere modeling with PHOENIX with extensive experience studying the highly irradiated class of ultra-hot Jupiters. Dr. Lothringer has also modeled brown dwarf and stellar atmospheres and has built a retrieval framework around PHOENIX. Dr. Lothringer is PI of recently approved small Program 16086. Prof. Sing is an expert in the analysis and interpretation of HST datasets, particularly of exoplanets. Prof. Sing also has experience studying white dwarf-main sequence binaries with HST. Prof. Sing is also an expert in calculating atmosphere models to interpret HST observations, particularly with the ATMO code. Prof. Sing has been PI of several HST programs, including small, large, and Treasury programs. Prof. Apai is the PI of Program 15947, the survey of BDs in WD systems that we will complement with our modeling. Prof. Apai has extensive experience analyzing and interpreting HST observations of brown dwarfs. Prof. Apai has been PI of several HST programs, including small, large, and AR programs. Stellar Physics and Stellar Types 0 Regular false false false true false SUPPORTED