ASD Colloquium Series
|How Stellar Activity can be Good for Life
Dr. Paul Rimmer (University of Cambridge, UK)
It is likely that the building blocks of life were formed photochemically from hydrogen cyanide on the surface of the Early Earth. This requires both sufficient UV light and a source of hydrogen cyanide (HCN). Flares and coronal mass ejections (CMEs) on stars are not always detrimental to habitability. CMEs ionize and dissociate molecular nitrogen, providing a source of atmospheric HCN that is orders of magnitude more efficient than photochemistry near a planet’s surface, where the HCN is needed. Additionally, when considering the rates to form sugars in the presence of the UV light and HCN, and the rates at which inert adducts form in the dark, and comparing with UV spectra of cool stars, we find that sufficiently active M dwarfs, with flares of energy greater than 5e34 erg with frequency greater than than once every 50 days, may provide enough energy to drive the formation of sugars. We are most interested in planets on which life started long ago, since it is unlikely we will be able to detect life that has just begun on an exoplanetary surface. Therefore it is important to have a good understanding of how flare rates change with stellar age.
ASD Colloquia are Tuesdays at 3:45 pm (Meet the Speaker at 3:30 pm) in Bldg 34, Room W150 unless otherwise noted.
|Date||August 07, 2018|
|Start/End Time||03:45 PM - 05:00 PM|
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