Nucleosynthesis and molecular processes in the late stages of Stellar Evolution

    General
    Description

    Low- to intermediate-mass (M < 8 solar masses, Ms) stars represent the majority of stars in the Cosmos. They finish their lives on the Asymptotic Giant Branch (AGB) - just before they form planetary nebulae (PNe) - where they experience complex nucleosynthetic and molecular processes. AGB stars are important contributors to the enrichment of the interstellar medium where new stars/planets are born (including our own Early Solar System, ESS), and to the chemical evolution of stellar systems like globular clusters (GCs) and galaxies. In particular, the more massive (M > 4-5 Ms) AGB stars synthesize very different (radio)isotopes from those formed by lower mass AGB stars and Supernova detonations, as a consequence of different nucleosynthesis mechanisms. Evolved stars in the transition phase between AGB stars and PNe also form diverse organic compounds like PAHs, and fullerene and graphene molecular nanostructures, being a wonderful laboratory for Astrochemistry. On-going massive surveys like SDSS-IV/APOGEE-2 and the upcoming James Webb Space Telescope (JWST) represent a fundamental step forward to understand the nucleosynthesis and molecular processes in evolved stars. We aim to explore the nucleosynthesis of light and heavy (radio)isotopes in AGB stars and how they contribute to the ESS radioactive inventory as well as to the formation and evolution of GCs and galaxies. We also aim at understanding the top-down formation process of fullerene and graphene molecular nanostructures in evolved stars. Finally, it is intended to perform data mining with the Gaia satellite, in order to study the AGB- PNe evolutionary phase. In addition we aim to use the GALEX database to discover binary central stars in Galactic PNe.

    Principal investigator

    1. During 2020, we have published 37 papers in high-impact international refereed astronomical journals (including one invited review) and 2 papers in the Chemistry -Physics journal FNCN.

    2. Phosphorus-rich stars with an extremely peculiar chemical abundance pattern have been discovered for the first time, challenging the theoretical nucleosynthesis predictions.

    3. It was demonstrated that the P-rich star progenitors represent a new site for s-process nucleosynthesis, with important implications for the chemical evolution of our Galaxy.

    Related publications

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      We investigate the inner regions of the Milky Way using data from APOGEE and Gaia EDR3. Our inner Galactic sample has more than 26 500 stars within |XGal|< 5 kpc, |YGal|< 3.5 kpc, |ZGal|< 1 kpc, and we also carry out the analysis for a foreground-cleaned subsample of 8000 stars that is more representative of the bulge-bar populations. These samples

      Queiroz, A. B. A. et al.

      Advertised on:

      12
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    • Planetary nebulae in Gaia EDR3: Central star identification, properties, and binarity

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      Advertised on:

      12
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    • Final Targeting Strategy for the Sloan Digital Sky Survey IV Apache Point Observatory Galactic Evolution Experiment 2 North Survey

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      Advertised on:

      12
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      Advertised on:

      11
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    • AGB Stars and Their Circumstellar Envelopes: An Operative Approach to Computing Their Atmospheres

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      Cristallo, Sergio et al.

      Advertised on:

      9
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      Nanni, Ambra et al.

      Advertised on:

      3
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      Magrini, L. et al.

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      8
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    • Double-lined Spectroscopic Binaries in the APOGEE DR16 and DR17 Data

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      Advertised on:

      11
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      Washington, Jasmin E. et al.

      Advertised on:

      9
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    • Alternative Strategies to Solve the Stellar Atmosphere Problem

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      Crivellari, L.

      Advertised on:

      6
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    • Testing the Limits of Precise Subgiant Characterization with APOGEE and Gaia: Opening a Window to Unprecedented Astrophysical Studies

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      Godoy-Rivera, Diego et al.

      Advertised on:

      7
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      Mészáros, Szabolcs et al.

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      8
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    • Chemodynamically Characterizing the Jhelum Stellar Stream with APOGEE-2

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      Advertised on:

      5
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    • APOGEE view of the globular cluster NGC 6544

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      Gran, F. et al.

      Advertised on:

      7
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    • An enquiry on the origins of N-rich stars in the inner Galaxy based on APOGEE chemical compositions

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      Kisku, Shobhit et al.

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      6
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    • The APOGEE Data Release 16 Spectral Line List

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      Smith, Verne V. et al.

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