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Astronomy Colloquium
"X-raying the Intersellar Medium"
Date: Thursday, February 6th
Time: 3:30 pm
Place: 4421 Sterling Hall, Coffee and cookies 3:30 PM, Talk begins 3:45 PM
Speaker: Dr. Eddie Schalfly, Lawrence Berkeley National Laboratory
Abstract: The interstellar medium (ISM) is the fuel of star formation, and its scattering and absorption of light transforms the Galactic radiation field. Despite its importance, most observations of the Milky Way's ISM are limited to two dimensions; its angular distribution is precisely measured, but its distribution in distance is much more uncertain. Large surveys of stars can be used to resolve this uncertainty. Because light from stars is absorbed and scattered by intervening material before observation on earth, the Galaxy's stars can be used as a dense network of lighthouses, effectively x-raying the ISM to reveal its 3D structure and properties. In this talk, I'll describe our ongoing program to use large surveys to map the ISM in 3D. We have mapped the density of dust in the ISM over the nearest 5 kpc at unprecedented resolution, highlighting complex networks of diffuse voids and dense star-forming regions. We have also been able to measure the size distribution of dust grains throughout the Milky Way, revealing kiloparsec-scale structures that may track variations in the Galactic star-formation rate and gas density. Numerous other projects are possible, ranging from studies of the 3D kinematics of the ISM to the Galactic magnetic field. New surveys and instruments like Gaia, SDSS-V, LSST, and JWST promise a bright future for 3D studies of the ISM, offering incredibly accurate distance measurements, order-of-magnitude larger samples of stars, and unrivalled sensitivitity.
Host: Bob Benjamin, UWM
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