Astronomy Colloquium

A significant fraction of the heavy elements produced by stars spend some time in the interstellar medium as dust grains.  These heavy metal transporters influence gas cooling during star formation, eventually becoming the seeds for planet formation.  Observations of X-ray bright Galactic compact objects can yield key insights to the mineralogy and evolution of dust grains in the Milky Way.  With high resolution X-ray spectroscopy, we can directly measure the state of metals and the mineral composition of dust in the interstellar medium.  In addition, dust scattering produces a diffuse halo image around bright X-ray objects, revealing information about dust grain sizes and their spatial distribution.  I will review the most recent exciting dust scattering discoveries, which draw on multi-wavelength observations. I will show how X-ray studies of the ISM are important for interpreting accretion by compact objects and the supermassive black hole at the center of our galaxy. Finally, I will discuss open questions regarding our X-ray view of the dusty Universe that can be addressed with future X-ray observatories.