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

    The Apache Point Observatory Galactic Evolution Experiment (APOGEE) 2017AJ....154...94M
    Atypical Mg-poor Milky Way Field Stars with Globular Cluster Second-generation-like Chemical Patterns 2017ApJ...846L...2F
    The evolution of Galactic planetary nebula progenitors through the comparison of their nebular abundances with AGB yields 2017MNRAS.471.4648V
    Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe 2017AJ....154...28B
    The Correlation between Mixing Length and Metallicity on the Giant Branch: Implications for Ages in the Gaia Era 2017ApJ...840...17T
    Asymptotic giant branch and super-asymptotic giant branch stars: modelling dust production at solar metallicity 2017MNRAS.467.4431D
    Red giants observed by CoRoT and APOGEE: The evolution of the Milky Way's radial metallicity gradient 2017A&A...600A..70A
    Two groups of red giants with distinct chemical abundances in the bulge globular cluster NGC 6553 through the eyes of APOGEE 2017MNRAS.465...19T
    Chemical tagging with APOGEE: discovery of a large population of N-rich stars in the inner Galaxy 2017MNRAS.465..501S
    Chemical Abundances of M-dwarfs from the APOGEE Survey. I. The Exoplanet Hosting Stars Kepler-138 and Kepler-186 2017ApJ...835..239S
    APOGEE chemical abundances of globular cluster giants in the inner Galaxy 2017MNRAS.466.1010S
    Galactic archaeology with asteroseismology and spectroscopy: Red giants observed by CoRoT and APOGEE 2017A&A...597A..30A
    Clear Evidence for the Presence of Second-generation Asymptotic Giant Branch Stars in Metal-poor Galactic Globular Clusters 2015ApJ...815L...4G
    Evidence for a metal-poor population in the inner Galactic bulge 2015A&A...584A..45S
    The SDSS-III APOGEE Spectral Line List for H-band Spectroscopy 2015ApJS..221...24S
    AGB stars in the SMC: evolution and dust properties based on Spitzer observations 2015MNRAS.454.4235D
    An Infrared Diffuse Circumstellar Band? The Unusual 1.5272 Micron DIB In the Red Square Nebula 2015ApJ...811..119Z
    Abundances, Stellar Parameters, and Spectra from the SDSS-III/APOGEE Survey 2015AJ....150..148H
    The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III 2015ApJS..219...12A
    High-resolution Imaging of NGC 2346 with GSAOI/GeMS: Disentangling the Planetary Nebula Molecular Structure to Understand Its Origin and Evolution 2015ApJ...808..115M
    Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk 2015ApJ...808..132H
    The radial abundance gradient of chlorine in the Milky Way 2015MNRAS.452.1553E
    A test for asymptotic giant branch evolution theories: planetary nebulae in the Large Magellanic Cloud 2015MNRAS.452.3679V
    Constraint on the time variation of the fine-structure constant with the SDSS-III/BOSS DR12 quasar sample 2015MNRAS.452.4153A
    Rapid Rotation of Low-mass Red Giants Using APOKASC: A Measure of Interaction Rates on the Post-main-sequence 2015ApJ...807...82T
    Young α-enriched giant stars in the solar neighbourhood 2015MNRAS.451.2230M
    On the C60 Fullerene Adduct with Pentacene: Synthesis and Stability
    Chemical Thermodynamics Applied to the Diels–AlderReaction of C60 Fullerene with Polyacenes
    New H-band Stellar Spectral Libraries for the SDSS-III/APOGEE Survey 2015AJ....149..181Z
    The Large Magellanic Cloud as a laboratory for hot bottom burning in massive asymptotic giant branch stars 2015MNRAS.450.3181V
    Exploring Anticorrelations and Light Element Variations in Northern Globular Clusters Observed by the APOGEE Survey 2015AJ....149..153M
    The APOGEE Spectroscopic Survey of Kepler Planet Hosts: Feasibility, Efficiency, and First Results 2015AJ....149..143F
    Asymptotic giant branch stars in the Large Magellanic Cloud: evolution of dust in circumstellar envelopes 2015MNRAS.447.2992D
    A search for diffuse bands in fullerene planetary nebulae: evidence of diffuse circumstellar bands 2015A&A...573A..97D
    Tracking Advanced Planetary Systems (TAPAS) with HARPS-N . I. A multiple planetary system around the red giant star TYC 1422-614-1 2015A&A...573A..36N
    Mapping the Interstellar Medium with Near-infrared Diffuse Interstellar Bands 2015ApJ...798...35Z
    The APOKASC Catalog: An Asteroseismic and Spectroscopic Joint Survey of Targets in the Kepler Fields 2014ApJS..215...19P
    The Present and Future of Planetary Nebula Research. A White Paper by the IAU Planetary Nebula Working Group 2014RMxAA..50..203K
    Tracing Chemical Evolution over the Extent of the Milky Way's Disk with APOGEE Red Clump Stars 2014ApJ...796...38N
    The APOGEE Red-clump Catalog: Precise Distances, Velocities, and High-resolution Elemental Abundances over a Large Area of the Milky Way's Disk 2014ApJ...790..127B

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