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Astrophysics Colloquium

Hubble's Ultraviolet View of Protoplanetary Disks and Exoplanetary Environments
Presented by Kevin France
Department of Astrophysical and Planetary Science, University of Colorado

Friday, March 13, 2015
12:00 noon in 169-336

The composition and spatial distribution of molecular gas in the inner few AU of young (< 10 Myr) circumstellar disks are important components to our understanding of the formation of planetary systems. In the first part of this talk, I will discuss the current, observationally-based picture of protoplanetary gas disks at r < 10 AU, reviewing the most widely used spectral diagnostics of the inner disk, and highlight recent observations of H2 and CO made by the Hubble Space Telescope. I will describe how molecular spectroscopy is being used to constrain the distribution of gas in the inner disk at spatial scales too small to resolve with current imaging instruments/facilities.

In the second part of this talk, I will discuss how the spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. I will present results from a panchromatic (Hubble/Chandra/XMM/optical) Hubble Treasury program that is currently underway to characterize the energetic radiation environments around low-mass host stars for the first time. We find that all exoplanet host stars observed to date exhibit some level of UV/X-ray activity, and that strong flares and stochastic variability are common, even on "optically inactive" M dwarfs hosting planetary systems. I will briefly discuss the use of these data in atmospheric models of rocky planets around cool stars, including the predicted abiotic production of O2 and O3 - a cautionary tale for the interpretation of "biomarker" gases when they are detected in the coming decades.

JPL Contact: Paul Johnson (3-4749)

SVCP Astrophysics

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