Astronomy with Radioactivities [joint colloquium with Astronomy] – Dieter Hartmann

Date: Thu. April 24th, 2008, 4:15 pm-5:15 pm
Location: Rockefeller 301

The production and distribution of new isotopes is a key topic of the astrophysical theme of chemical evolution. We distinguish Galactic Chemical Evolution (GCE), which is concerned with abundances in stars and the Interstellar Medium (ISM), and Cosmic Chemical Evolution (CCE), which extends this research to galaxies, clusters of galaxies, and the Intergalactic Medium (IGM). The ultimate goal is to understand the origin and evolution of all known nuclei, their abundances in various environments, ranging from planetary- to stellar systems. The cosmic cycle is driven by the formation, evolution, and deaths of stars. Strong winds and explosive final stages of massive stars determine the chemical, but also the structural evolution of gas-star systems like galaxies. The energetic feedback from supernovae alters the ISM, and can lead to star-burst driven outflows on large scales, in extreme cases. When the chemical and energetic effects are considered together, one speaks of chemo-dynamics. We thus wish to develop models of GCD and CCD, where D stands for Dynamics. This is a very broad field, and in this colloquium the focus will be on the contribution from a small, but special, set of isotopes: specifically the radioactive species 26Al, 60Fe, and 44Ti. We discuss how gamma-ray line astronomy has contributed to this area of astrophysics, with missions such as the Compton Gamma-Ray Observatory (CGRO) and INTEGRAL, and give an outlook to the future.