Tuesday

Understanding how and where the first heavy elements formed in the Universe
remains one of the open questions in physics. Using the chemical abundance
information from some of the oldest stars is an excellent tool to answer such questions.
As observations go deeper and deeper and more sky scanning surveys are
commissioned, we gain knowledge on these old, low-mass stars and their chemical
composition. Most of the oldest stars with low Fe-content have proven to be
C-enhanced, and we can further classify and understand these stars based on
their heavy element content. We have studied various types of CEMP stars over a wide range of metallicities allowing us to probe the earliest as well as later stages of the chemical evolution of the Galaxy (GCE).
Moreover, these stars are excellent GCE tracers in some of the upcoming surveys,
where I have explored the spectral information that we can hope to gain from,
e.g., 4MOST. In addition to these old CEMP stars, another class of promising
trace stars are the intrinsically old RR Lyr stars, where we have discovered the
most metal-poor (oldest) of this type of stars known to date. I will present
high-resolution spectroscopic analyses of these old stars residing in both the
halo and bulge and use them to narrow down the number of neutron-capture
formation processes needed to explain the chemistry of the early Galaxy and its
further evolution.