The oldest stars of the bulge: new information on the ancient Galaxy

TL;DR

This paper investigates the oldest stars in the Galactic bulge, revealing new chemical signatures that enhance understanding of early star formation and Galactic evolution, especially regarding the first stellar generations and their impact on the interstellar medium.

Contribution

It provides new observational data on the chemical composition of ancient bulge stars, offering insights into the nature of the first stars and their role in Galactic chemical enrichment.

Findings

Old bulge stars show unique chemical signatures.

Evidence supports fast-rotating first stellar generations.

Results constrain models of early Galactic evolution.

Abstract

Recently the search for the oldest stars have started to focus on the Bulge region. The Galactic bulge hosts extremely old stars, with ages compatible with the ages of the oldest halo stars. The data coming from these recent observations present new chemical signatures and therefore provide complementary constraints to those already found in the halo. So, the study of the oldest bulge stars can improve dramatically the constraints on the nature of first stars and how they polluted the pristine ISM of our Galaxy. We present our first results regarding the light elements (CNO) and the neutron capture elements. Our findings in the oldest bulge stars support the scenario where the first stellar generations have been fast rotators.