Department of Physics
Research, teaching and outreach in Physics at UW–Madison

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Astronomy Colloquium
Understanding the Interstellar Neighborhood: Structure, Dynamics, and Quasar Scintillation"
Date: Tuesday, October 28th
Time: 3:30 pm
Place: 6515 Sterling Hall
Speaker: Dr. Jeff Linsky, UC- Boulder
Abstract: Absortion line spectroscopy provides a precise tool for understanding the properties of gas in the very local region of the Galactic disk and by implication interstellar media elsewhere in the universe. I will describe our recent studies of the dynamics and structure of local warm gas based on high-resolution HST and ground based Ca II spectra. Analysis of 157 sight lines shows that most velocity components can be modeled with 15 velocity vectors indicating the presence of 15 parcels of warm gas located within a few parsecs of the Sun. Cloud-cloud interactions may explain the morphologies and physical properties of these clouds.<br>
Large-amplitude intraday and annual variability of quasars can be simply explained as scintillation produced by nearby turbulent-scattering screens.<br>
I will show that the scattering screens are located near the edges of nearby warm clouds and that the turbulence responsible for the scattering could be explained by the interaction of clouds with large differences in radial and transverse velocities.
Host: Professor Blair Savage
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