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 Similarity of Abundance Ratio Trends and Nucleosynthetic Patterns in the Milky Way Disk and Bulge 2021ApJ...909...77G
    The APOGEE Library of Infrared SSP Templates (A-LIST): High-resolution Simple Stellar Population Spectral Models in the H Band 2021AJ....161..167A
    Probing 3D and NLTE models using APOGEE observations of globular cluster stars 2021A&A...647A..24M
    An Intermediate-age Alpha-rich Galactic Population in K2 2021AJ....161..100W
    Atomic data for the Gaia-ESO Survey 2021A&A...645A.106H
    Are extreme asymptotic giant branch stars post-common envelope binaries? 2021MNRAS.502L..35D
    Low-mass low-metallicity AGB stars as an efficient i-process site explaining CEMP-rs stars 2021A&A...645A..61K
    The contribution of N-rich stars to the Galactic stellar halo using APOGEE red giants 2021MNRAS.500.5462H
    Carbon-enhanced metal-poor stars enriched in s-process and r-process elements 2020JApA...41...46K
    Exploring the Galactic Warp through Asymmetries in the Kinematics of the Galactic Disk 2020ApJ...905...49C
    Wide binaries in planetary nebulae with Gaia DR2 2020A&A...644A.173G
    Heavy-element Abundances in P-rich Stars: A New Site for the s-process? 2020ApJ...904L...1M
    Open Cluster Chemical Homogeneity throughout the Milky Way 2020ApJ...903...55P
    The Gaia-ESO Survey: Calibrating the lithium-age relation with open clusters and associations. I. Cluster age range and initial membership selections 2020A&A...643A..71G
    How many components? Quantifying the complexity of the metallicity distribution in the Milky Way bulge with APOGEE 2020MNRAS.499.1037R
    The Gaia-ESO Survey: A new diagnostic for accretion and outflow activity in the young cluster NGC 2264 2020A&A...642A..56B
    Cool stars in the Galactic center as seen by APOGEE. M giants, AGB stars, and supergiant stars and candidates 2020A&A...642A..81S
    Exploring the Stellar Age Distribution of the Milky Way Bulge Using APOGEE 2020ApJ...901..109H
    Geometry of the Draco C1 Symbiotic Binary 2020ApJ...900L..43L
    The Milky Way's bulge star formation history as constrained from its bimodal chemical abundance distribution 2020MNRAS.497.3557L
    Phosphorus-rich stars with unusual abundances are challenging theoretical predictions 2020NatCo..11.3759M
    APOGEE Data and Spectral Analysis from SDSS Data Release 16: Seven Years of Observations Including First Results from APOGEE-South 2020AJ....160..120J
    The age-chemical abundance structure of the Galactic disc - II. α-dichotomy and thick disc formation 2020MNRAS.497.2371L
    Assessing spectra and thermal inversions due to TiO in hot Jupiter atmospheres 2020MNRAS.496.3870P
    Strong chemical tagging with APOGEE: 21 candidate star clusters that have dissolved across the Milky Way disc 2020MNRAS.496.5101P
    Physical characterization of 2020 AV<SUB>2</SUB>, the first known asteroid orbiting inside Venus orbit 2020MNRAS.496.3572P
    The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra 2020ApJS..249....3A
    The SDSS/APOGEE catalogue of HgMn stars 2020MNRAS.496..832C
    From the bulge to the outer disc: StarHorse stellar parameters, distances, and extinctions for stars in APOGEE DR16 and other spectroscopic surveys 2020A&A...638A..76Q
    A theoretical investigation of the possible detection of C24 in space 2020FNCN...28..637S
    Detection of CH<SUP>+</SUP>, CH and H<SUB>2</SUB> Molecules in the Young Planetary Nebula IC 4997 2020PASP..132g4201R
    The Lazy Giants: APOGEE Abundances Reveal Low Star Formation Efficiencies in the Magellanic Clouds 2020ApJ...895...88N
    Close Binary Companions to APOGEE DR16 Stars: 20,000 Binary-star Systems Across the Color-Magnitude Diagram 2020ApJ...895....2P
    Petroleum, coal and other organics in space 2020Ap&SS.365...81C
    Spectral Classification of B Stars: The Empirical Sequence Using SDSS-IV/APOGEE Near-IR Data 2020ApJ...894....5R
    Identification of a Group III CEMP-no Star in the Dwarf Spheroidal Galaxy Canes Venatici I 2020ApJ...894....7Y
    [Li@C60]PF6: Infrared spectra from 90K to 523K; Determination of the molar extinction coefficients and integrated molar absorptivity 2020FNCN...28..474G
    The age-chemical abundance structure of the Galaxy I: evidence for a late-accretion event in the outer disc at z ∼ 0.6 2020MNRAS.494.2561L
    The Open Cluster Chemical Abundances and Mapping Survey. IV. Abundances for 128 Open Clusters Using SDSS/APOGEE DR16 2020AJ....159..199D
    The chemical compositions of accreted and in situ galactic globular clusters according to SDSS/APOGEE 2020MNRAS.493.3363H

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