Speaker: Alex Dimoff (Stellar spectroscopy and populations research group at MPIA)

Title: s-Process Signatures of Binary Interaction across the Milky Way

Abstract: Spectroscopic observations of neutron-capture elements provide a powerful tracer of the chemical evolution of the Milky Way across both stellar and Galactic scales. In this talk, I will present a project that links observations of s-process elements to binary accretion histories, and extend this to the chemical evolution of the Galaxy. Post-accretion systems like Barium (Ba), CH, and carbon-enhanced metal-poor (CEMP-s) stars preserve the chemical signatures of past accretion from an asymptotic giant branch (AGB) companion. These binary systems encode key information about how s-process material is redistributed between stars and into the interstellar medium. Comparing high-resolution observations to detailed binary-evolution models (STARS, ELC) combined with AGB nucleosynthesis yields from FRUITY, I investigate how mass-transfer influences both the efficiency of material transfer and the resulting abundance patterns. We find that the donor AGB mass directly shapes the neutron-capture element ratios observed in the companion, and that low-metallicity systems (CH, CEMP-s) tend to accrete less material (< 0.3 M_sun) than their higher-metallicity counterparts (Ba) (> 0.3 M_sun). This metallicity dependent accretion has direct implications for the enrichment of the Galactic halo versus the disc, where distinct s-process patterns trace different stellar populations formed during the Milky Way’s assembly. Finally, I will touch on emerging work at MPIA exploring how the Galactic distribution of long-lived radioisotopes may influence the radiogenic heating and internal evolution of rocky exoplanets. Together, these results bridge planetary and stellar physics, binary evolution, and Galactic archaeology, offering a unified framework for how interacting stars shape the chemical evolution of the Milky Way and its planets.

• Date:
  Nov. 21, 2025, 11 a.m. – noon
  
  
• Location:

  AIP; Kirch building, Seminar room behind the Moon

  
  
• Contact:
  nkacharov@aip.de