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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/041/0047

    • Keywords

       

      Stars; nucleosynthesis; i-process.

    • Abstract

       

      The surface chemical compositions of a large fraction of carbon-enhanced metal-poor (CEMP) stars, the so-called CEMP-r/s stars, are known to exhibit enhancement of both s-process and r-process elements. For these stars, the heavy-element abundances cannot be explained either by s-process or r-processnucleosynthesis alone, as the production sites of s-process and r-process elements are very different, and these two processes produce distinct abundance patterns. Thus, the observational evidence of the doubleenhancement seen in CEMP-r/s stars remains a puzzle as far as the origin of the elements is concerned. In this work, we have critically analysed the observed abundances of heavy elements in a sample of eight CEMP-r/s stars from the literature to trace the origin of the observed double enhancement. Towards this, we have conducted a parametric-model-based analysis to delineate the contributions of s-process and r-process nucleosynthesis to the observed elemental abundances. We have further examined if the i-process (intermediate-process) nucleosynthesis that occurs at high neutron density (${\rm n} \sim 10^{15}$ cm$^{-3}$) produced during proton ingestion from a H-rich envelope to the intershell region of an AGB star, which is capable of producing both r-process and s-process elements in a single stellar site, could explain the observed abundance patterns of the sample stars. Our analysis shows that the observed abundance patterns of the selected sample of CEMP-r/s stars could be fairly well reproduced using the i-process model yields.

    • Author Affiliations

       

      PARTHA PRATIM GOSWAMI1 ARUNA GOSWAMI1

      1. Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bengaluru 560034, India.
    • Dates

       
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