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Astronomy Colloquium
Casting Shadows on the standard intersteller medium paradign with GALFA-HI
Date: Thursday, October 7th
Time: 3:30 pm
Place: 4421 Sterling Hall Same Location
Speaker: Josh Peek, Columbia University
Abstract: Our understanding of the diffuse interstellar medium (ISM) revolves around the balance of pressures between warm and cold phases and the interruption of that balance by the explosion of stars in supernovae. I will show new results enabled by the GALFA-HI survey that throw these standard theoretical underpinnings into disarray. I will discuss our investigation of the nearest cold neutral medium (CNM) to the sun, deep within the boundaries of the local cavity. High spectral resolution observations of this object present interesting constraints to theorists and simulators who propose that CNM clouds are formed by the collision of warmer clouds. Observations of the absorption of soft X-rays by this CNM show that X-rays emanate much nearer to the sun than was thought before, casting doubt on the local hot bubble theory. We have also investigated hundreds of compact HI clouds in our Galaxy, many of which seem to be in extreme force imbalance with the expected ambient ISM. These finding all suggest we have much to learn about the Galactic ISM we call home.
Host: Snezana Stanimirovic
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