Benne Holwerde (University of Louisville)
Galaxies are made up of stars, gas, dark matter and dust. That last ingredient is only a small amount of the total but radically changes our view of galaxies. Up to half the starlight in a given galaxy could be invisible thanks to the small amount of dust. Over decades, astronomy has sought to get away from dust to study the galaxies’ stars and to study the dust itself. This talk will focus on how dust dims and reddens the starlight in galaxies other than our Milky Way. It is tricky to identify if a part of a galaxy is dark because the stars are hidden by dust or simply because there is nothing there. We will touch upon techniques to find where and how much dust there is in the swirls of spiral galaxies. Lately, accidentally overlapping galaxies show in vivid detail where the dust spreads throughout the foreground galaxy. These make for some spectacular Hubble images.
Bio: Benne Holwerda received his Ph.D. in Astronomy from the University of Groningen, the Netherlands in 2005. He is now an associate professor of astronomy at the University of Louisville, after working at the Space Telescope Science Institute, the University of Cape Town, the European Space Agency and Leiden Observatory. His scientific interests lie in the evolution of galaxies, the role of dust and gas in galaxy evolution and appearance.