0 Assigned ID: 626 ----- Attempting Submission 1 (Fri Apr 05 18:46:05 GMT 2019) ----- HST Phase I Proposal 626 (submitted_version1.apt) successfully submitted. Receipt: # 626-1 ----- Attempting Submission 2 (Fri Apr 05 20:55:51 GMT 2019) ----- Phase II ID is a required field. Couldn't identify "AR" as a legal selection. Observing Description is a required field. 0 Planets lose mass over the course of their lives, shaping the observed population. The Hubble Space Telescope has been our premier tool for observing this process in action over the past fifteen years, using UV spectroscopy targeting escaping hydrogen and, more recently, IR spectroscopy targeting escaping helium. We have now observed atmospheric escape from over half a dozen planets. HST has studied many of these planets extensively using transmission spectroscopy during transit, revealing that most of these planets, from hot Jupiters, to warm Neptunes, to low-gravity 'super puffs', have muted transmission spectra compared to cloud-free model atmospheres. Wang and Dai (2019) recently proposed that these two observations--atmospheric escape and muted spectra--could be intrinsically linked for very low-gravity planets, with dust entrained in outflows obscuring observed spectra. We propose to use theoretical simulations of mass loss, exospheric transmission spectra, and cloud/haze formation and destruction to investigate this proposed mechanism. We will apply these new models to a broad range of planets, including 3 hot Jupiters, 3 warm Neptunes, and 2 super puffs. Each planet we consider has an observed transmission spectrum with HST; the Jupiters and Neptunes have detected H or He exospheres; and the super puffs are expected to be in the process of losing their envelopes. Using these simulations, we seek to investigate whether this dusty outflow mechanism well above the hydrostatic atmosphere is obscuring our views of exoplanets during transit, muting their features. If so, this has broad implications for past and future exoplanet observations with HST and JWST. PI Dr. Caroline Morley is an assistant professor of astronomy at the University of Texas at Austin. She has extensive experience in modeling the atmospheres of exoplanets and brown dwarfs, including modeling the transmission, emission, and reflected light spectra. She is an expert in cloud and haze formation in a broad range of planets from cold free-floating planets to hot irradiated planets. PI Morley has developed the transmission spectra and cloud modeling tools that will be used in the proposed investigation. Co-I Dr. Eric Lopez is an exoplanetary atmospheric theorist specializing in 1-D models of planet interiors, evolution, and atmospheric escape for transiting planets. Co-I Lopez received a PhD in Astronomy & Astrophysics from UC Santa Cruz in 2014 and since 2017 has been a research astrophysicist in the Planetary Systems Lab at NASA Goddard. Co-I Lopez has developed 1-D models of photo-evaporative atmospheric escape which will be used to estimate the flow rates and densities in the upper atmospheres of planets experiencing escape which will be used in this proposal. Planets and Planet Formation 0 Regular false false false true false SUPPORTED