COLLOQUIUM Alexander Heger, Monash University

Finding the Oldest Star

The discovery of entire, apparently well-developed, galaxies at unexpectedly high red shifts by JWST has fuelled new interest in the very first stars that must have stood at the beginning of these galaxies. The first stars mark the transition from the cosmic dark ages to the modern universe that we know today, a universe that is filled with stars, galaxies, and heavy elements essential to life. The first stars stand out because of their pristine primordial initial composition and their pre-galactic formation environment. Their unique composition dramatically alter their evolution, their structure, the way they die as supernovae, and their resulting nucleosynthesis. The special circumstances under which these stars were formed also impacts their characteristic initial mass distribution, the initial mass function. Generally, it is assumed that these stars typically were significantly more massive than present-day stars. No low-mass Population III star that could have survived to the present day has ever been found. I will give an overview of the evolution and death of these first stars and their supernova. I will discuss nucleosynthesis signatures as possible diagnostics we may use at the present day to learn about these first stars, and where to find these patterns --- with the interesting perspective of potentially identifying the oldest stars in our Milky Way, which may not be the most metal-poor.

Talk in presence and via Zoom:

https://uni-hamburg.zoom.us/j/66006535328?pwd=aGkrSjJIYmZjK0VpYlpGL0ZrdHg2UT09

This talk is not part of the seminar on astrophysics. Everybody is welcome though.