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Cornell Department of Astronomy & Space Sciences Fall 2021 Colloquium Series

Thursday, October 14, 2021 at 4:00pm to 5:00pm

Space Sciences Building, 105

"The Far Ultraviolet diffuse background"

ABSTRACT:  Historically, the search for the inter-galactic medium (IGM) motivated the search for  the Far Ultraviolet (FUV) background which in turn led to a number of experiments and missions.  Decades later the focus shifted to FUV as the primary heating and ionizing agent of the atomic phases (warm and cold neutral medium).  The current view is that the diffuse FUV emission, at high latitudes, has three components: FUV light from hot stars in the Galactic plane reflected by dust grains (diffuse galactic light or DGL), FUV from
other galaxies (extra-galactic background light, EBL) and a component
of unknown origin.  During the eighties, there was some discussion that decaying dark matter particles produced FUV radiation. In my talk I systematically investigate production of FUV photons by the Galactic Hot Ionized Medium (line emission) and two photon emissionfrom the  Warm Ionized Medium, the general class of low velocity shocks and from Lyman fluorescence in the Solar System (the interplanetary medium and  the exosphere of Earth).  I conclude that two thirds to perhaps all of the third component can be explained by the sum of the processes listed above.

Dial-In Information

The colloquia are held every Thursday afternoon 4-5 pm. The public is welcome. To view via Zoom, please contact Monica Carpenter ( or Jason Jennings ( for the link.

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Contact Name

Monica Carpenter

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Shri Kulkarni

Speaker Affiliation

California Institute of Technology

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