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

    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
    On the alumina dust production in the winds of O-rich asymptotic giant branch stars 2014MNRAS.441.1115D
    Chemical abundances in Galactic planetary nebulae with Spitzer spectra 2014A&A...567A..12G
    Dissecting the Spitzer colour-magnitude diagrams of extreme Large Magellanic Cloud asymptotic giant branch stars 2014MNRAS.442L..38D
    Circumstellar effects on the Rb abundances in O-rich AGB stars 2014A&A...564L...4Z
    Single Rotating Stars and the Formation of Bipolar Planetary Nebula 2014ApJ...783...74G
    The Tenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Apache Point Observatory Galactic Evolution Experiment 2014ApJS..211...17A
    Far infrared (terahertz) spectroscopy of a series of polycyclic aromatic hydrocarbons and application to structure interpretation of asphaltenes and related compounds
    Dust Around R Coronae Borealis Stars. II. Infrared Emission Features in an H-poor Environment 2013ApJ...773..107G
    Infrared spectroscopy of fullerene C60/anthracene adducts 2013MNRAS.434..415G
    Target Selection for the Apache Point Observatory Galactic Evolution Experiment (APOGEE) 2013AJ....146...81Z
    Hot bottom burning and s-process nucleosynthesis in massive AGB stars at the beginning of the thermally-pulsing phase 2013A&A...555L...3G
    The changing nebula around the hot R Coronae Borealis star DY Centauri 2013MNRAS.431..159K
    Photolytic Decomposition of Hydrogenated C70: C70H38 and C70D38
    Kinetic Isotope Effects on the Photolysis of C60H18 and C60D18
    Perdeuterofulleranes: Synthesis and Properties of C70D38 and C70H38
    Synthesis and FT-IR Spectroscopy of Perdeuterofullerane: C60D36 Evidences of Isotope Effect in the Stability of C60D36
    Low and High Temperature Infrared Spectroscopy of C60 and C70 Fullerenes
    A Simple Synthesis of C60H18 from C60 Fullerene and Hydrogen Iodide
    Characterization of Hydrogenated Fullerene Mixture of C60Hx and C70Hx
    Determination of the Integrated Molar Absorptivity and Molar Extinction Coefficient of Hydrogenated Fullerenes
    On the Radical Anion Spectra of Fullerenes C-60 and C-70
    Far- and mid-infrared spectroscopy of complex organic matter of astrochemical interest: coal, heavy petroleum fractions and asphaltenes 2013MNRAS.429.3025C
    Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connection 2013A&A...550L...6G
    Synthesis of polyphenylacetylene by radiation-induced polymerization in deoxycholic acid clathrate 2009RaPC...78..244C

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