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The Potential Habitability of Rocky Planets Around Red Dwarfs: Stellar Drivers for Atmospheric Chemistry and Stability

Event Details

Event Dates: 

Monday, November 6, 2017 - 4:00pm

Seminar Location: 

  • JILA Auditorium

Speaker Name(s): 

Kevin France

Speaker Affiliation(s): 

CU
Seminar Type/Subject

Scientific Seminar Type: 

  • Astrophysical & Planetary Sciences Seminar

Event Details & Abstract: 

High-energy photons and particles from stars regulate the atmospheric temperature structure and photochemistry on orbiting planets, influencing the long-term stability of planetary atmospheres and the production of potential “biomarker” gases. Rocky planets orbiting low-mass stars (M dwarfs) will likely be the first exoplanets directly probed for signs of life, however, relatively few observational and theoretical constraints exist on the high-energy irradiance from typical (i.e., weakly active) M dwarf exoplanet host stars. In this talk, I will describe results from an ongoing panchromatic survey (Chandra/XMM/Hubble/ground) of M and K dwarf exoplanet hosts. The MUSCLES* Treasury Survey combines UV, X-ray, and optical observations, reconstructed Lyman-alpha and EUV (10-90 nm) radiation, and next-generation stellar atmosphere models to provide realistic inputs for modeling the stability and climate on potentially habitable planets around red dwarfs.

I will present an overview of the project and focus on three main results – 1) the evolution of the high-energy spectral energy distribution as a star’s habitable zone moves inward from 1 to 0.1 AU, including implications for the possible abiotic production of the suggested biomarkers O2 and O3, 2) new estimates of the high-energy particle fluxes (from CMEs/SEPs) from these stars based on solar UV flare/particle flux measurements, and 3) characterization of the high-energy variability on active and inactive M dwarfs, with an emphasis on the potential for these impulsive events to drive large-scale atmospheric mass loss. I will conclude by presenting a short summary of our prospects for spectroscopically characterizing the atmospheres of potentially inhabited planets around M dwarfs in the next ~20 years.

* Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems