Cake Talk by Professor Maria Bergemann - MPI for Astronomy in Heidelberg & NBIA

One of the most exciting questions in modern astrophysics is what are the progenitors of Supernovae Ia (SN Ia). As endpoints of binary stellar evolution, SNIa's are primarily responsible for the nucleosynthesis of Fe-group elements, they influence the chemical enrichment and star formation history of galaxies, and - through their role as geometric probes of cosmic expansion - they underpin observational cosmology.

I will describe our long-term program to constrain the physical properties of SN Ia using the chemical abundances of galactic stars. This field has radically changed, as massive spectroscopic surveys and large facilities equipped with high-resolution spectrographs now allow us to probe the previously inaccessible regions of the Milky Way, its dwarf satellites, and other large star-forming galaxies in the Local Group. Also, major improvements in spectroscopic analysis methods and physical models of stellar spectra have made it possible to determine the chemical abundances of stars with unprecedented precision.

I will talk about Non-LTE chemical abundances of stars, and I will show how we can use them to trace the chemical evolution of the Galactic disc. I will then focus on the connections between the enrichment history of the Galaxy and the properties of SNIa’s that have dominated its evolution over the past 8 billion years. Finally, I will discuss the new evidence in the context of the environmental diversity of SN Ia's and relate it to the problem of residuals in the Hubble diagram.