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

    Short-lived radioactivity in the early solar system: The Super-AGB star hypothesis 2012M&PS..tmp..207L
    High-resolution Optical Spectroscopy of DY Cen: Diffuse Interstellar Bands in a Proto-fullerene Circumstellar Environment? 2012ApJ...759L..21G
    The Hot R Coronae Borealis Star DY Centauri is a Binary 2012ApJ...760L...3K
    Infrared Study of Fullerene Planetary Nebulae 2012ApJ...760..107G
    The mixed chemistry phenomenon in Galactic Bulge PNe 2009A&A...495L...5P
    Rubidium, zirconium, and lithium production in intermediate-mass asymptotic giant branch stars 2012A&A...540A..44V
    Oxygen Isotopic Ratios in Cool R Coronae Borealis Stars 2010ApJ...714..144G
    Outburst activity in comets - II. A multiband photometric monitoring of comet 29P/Schwassmann-Wachmann 1 2010MNRAS.409.1682T
    New groups of planetary nebulae with peculiar dust chemistry towards the Galactic bulge 2010A&A...516A..39G
    Heavy Element Nucleosynthesis in the Brightest Galactic Asymptotic Giant Branch Stars 2012ApJ...751....8K
    Evolution of tidal disruption candidates discovered by XMM-Newton 2008A&A...489..543E
    CNO Abundances of Hydrogen-Deficient Carbon and R Coronae Borealis Stars: A View of the Nucleosynthesis in a White Dwarf Merger 2009ApJ...696.1733G
    Are C60 Molecules Detectable in Circumstellar Shells of R Coronae Borealis Stars? 2011ApJ...729..126G
    A search for diffuse bands in the circumstellar envelopes of post-AGB stars 2008A&A...480..133L
    The role of massive AGB stars in the early solar system composition 2009M&PS...44..627T
    The Nature of Dust in Compact Galactic Planetary Nebulae from Spitzer Spectra 2012ApJ...753..172S
    The Intergalactic Stellar Population from Mergers of Elliptical Galaxies with Dark Matter Halos 2010ApJ...710.1589G
    The Interaction of Asymptotic Giant Branch Stars with the Interstellar Medium 2012ApJ...748...94V
    The chemical composition of the post-asymptotic giant branch F supergiant CRL 2688 2012MNRAS.425..997I
    Rb-Rich Asymptotic Giant Branch Stars in the Magellanic Clouds 2009ApJ...705L..31G
    Kinematical Analysis of a Sample of Bipolar Planetary Nebulae 2008AJ....135.2199D
    IRAS 17423-1755 (Hen 3-1475) Revisited: An O-rich High-mass Post-asymptotic Giant Branch Star 2011AJ....141...80M
    High-resolution spectroscopy of the high-velocity hot post-AGB star LS III +52°24 (IRAS 22023+5249) 2012MNRAS.421..679S
    Formation of Fullerenes in H-containing Planetary Nebulae 2010ApJ...724L..39G
    Far-infrared Imaging of Post-asymptotic Giant Branch Stars and (Proto)-planetary Nebulae with the AKARI Far-Infrared Surveyor 2011AJ....141..111C
    A Detailed look at Chemical Abundances in Magellanic Cloud Planetary Nebulae. I. The Small Magellanic Cloud 2010ApJ...717..562S
    EPOXI: Comet 103P/Hartley 2 Observations from a Worldwide Campaign 2011ApJ...734L...1M
    UV photolysis of polyynes at λ=254 nm and at λ>222 nm 2008IJAsB...7..107C
    The Chemical Composition of Cernis 52 (BD+31° 640) 2009ApJ...706..866G
    Stability of C60 and C70 fullerenes toward corpuscular and γ radiation 2009MNRAS.394..615C
    Solid state radiolysis of amino acids in an astrochemical perspective 2011RaPC...80...57C
    On the action of UV photons on hydrogenated fulleranes C60H36 and C60D36 2009MNRAS.400..291C
    Infrared spectroscopy of hydrogenated fullerenes (fulleranes) at extreme temperatures 2012MNRAS.423.2868I
    Infrared spectroscopy and integrated molar absorptivity of C60 and C70 fullerenes at extreme temperatures 2011MNRAS.413..213I
    Evidence for the Naphthalene Cation in a Region of the Interstellar Medium with Anomalous Microwave Emission 2008ApJ...685L..55I
    Amino acids in comets and meteorites: stability under gamma radiation and preservation of the enantiomeric excess 2011MNRAS.410.1447I
    A search for naphthalene in diffuse interstellar clouds 2012MNRAS.420.2785I
    A search for interstellar anthracene towards the Perseus anomalous microwave emission region 2010MNRAS.407.2157I
    A photometric redshift of z = 1.8{+0.4}{-0.3} for the AGILE GRB 080514B 2008A&A...491L..29R
    The Formation of Fullerenes: Clues from New C60, C70, and (Possible) Planar C24 Detections in Magellanic Cloud Planetary Nebulae 2011ApJ...737L..30G

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