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

    Characterization of M-stars in the LMC in the JWST era 2020MNRAS.493.2996M
    Stellar Characterization of M Dwarfs from the APOGEE Survey: A Calibrator Sample for M-dwarf Metallicities 2020ApJ...890..133S
    Characterizing the companion AGBs using surface chemical composition of barium stars 2020MNRAS.492.3708S
    Metallicity and α-Element Abundance Gradients along the Sagittarius Stream as Seen by APOGEE 2020ApJ...889...63H
    The Central Star of NGC 2346 as a Clue to Binary Evolution through the Common Envelope Phase 2019ApJ...885...84G
    Physical parameters of red supergiants in dwarf irregular galaxies in the Local Group 2019A&A...631A..95B
    Properties of central stars of planetary nebulae with distances in Gaia DR2 2019A&A...630A.150G
    Discovery of a nitrogen-enhanced mildly metal-poor binary system: Possible evidence for pollution from an extinct AGB star 2019A&A...631A..97F
    Homogeneous analysis of globular clusters from the APOGEE survey with the BACCHUS code - II. The Southern clusters and overview 2020MNRAS.492.1641M
    Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar 2019MNRAS.490.4740B
    Spatial variations in the Milky Way disc metallicity-age relation 2019MNRAS.489.1742F
    The Gaia-ESO survey: Calibrating a relationship between age and the [C/N] abundance ratio with open clusters 2019A&A...629A..62C
    Far infrared spectroscopy and other spectral and thermal properties of [Li@C60]PF6 2019FNCN...27..695C
    Toluene pyrolysis in an electric ARC: Products analysis 2019FNCN...27..469C
    H-band discovery of additional second-generation stars in the Galactic bulge globular cluster NGC 6522 as observed by APOGEE and Gaia 2019A&A...627A.178F
    ExoMol molecular line lists - XXXIII. The spectrum of Titanium Oxide 2019MNRAS.488.2836M
    Do evolved stars in the LMC show dual dust chemistry? 2019MNRAS.488L..85M
    TOI-150: A Transiting Hot Jupiter in the TESS Southern CVZ 2019ApJ...877L..29C
    The metal-rich halo tail extended in |z|: a characterization with Gaia DR2 and APOGEE 2019MNRAS.487.1462F
    Reduction of the maximum mass-loss rate of OH/IR stars due to unnoticed binary interaction 2019NatAs...3..408D
    AGB dust and gas ejecta in extremely metal-poor environments 2019MNRAS.486.4738D
    Chemical analysis of CH stars - III. Atmospheric parameters and elemental abundances 2019MNRAS.486.3266P
    High-resolution spectroscopy of Boyajian's star during optical dimming events 2019MNRAS.486..236M
    Exploring circumstellar effects on the lithium and calcium abundances in massive Galactic O-rich AGB stars 2019A&A...623A.151P
    Chemical Abundances of Main-sequence, Turnoff, Subgiant, and Red Giant Stars from APOGEE Spectra. II. Atomic Diffusion in M67 Stars 2019ApJ...874...97S
    Chemical Cartography with APOGEE: Multi-element Abundance Ratios 2019ApJ...874..102W
    Massive Stars in the SDSS-IV/APOGEE-2 Survey. II. OB-stars in the W345 Complexes 2019ApJ...873...66R
    Discovery of Resolved Magnetically Split Lines in SDSS/APOGEE Spectra of 157 Ap/Bp Stars 2019ApJ...873L...5C
    J-PLUS: Identification of low-metallicity stars with artificial neural networks using SPHINX 2019A&A...622A.182W
    Homogeneous analysis of globular clusters from the APOGEE survey with the BACCHUS code. I. The northern clusters 2019A&A...622A.191M
    Identifying Sagittarius Stream Stars by Their APOGEE Chemical Abundance Signatures 2019ApJ...872...58H
    Constraining Metallicity-dependent Mixing and Extra Mixing Using [C/N] in Alpha-rich Field Giants 2019ApJ...872..137S
    APOGEE [C/N] Abundances across the Galaxy: Migration and Infall from Red Giant Ages 2019ApJ...871..181H
    The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA-derived Quantities, Data Visualization Tools, and Stellar Library 2019ApJS..240...23A
    The Gaia-ESO Survey: impact of extra mixing on C and N abundances of giant stars 2019A&A...621A..24L
    Kepler-730: A Hot Jupiter System with a Close-in, Transiting, Earth-sized Planet 2019ApJ...870L..17C
    Chemical and Kinematic Analysis of CN-strong Metal-poor Field Stars in LAMOST DR3 2019ApJ...871...58T
    Discovery of Stars Surrounded by Iron Dust in the Large Magellanic Cloud 2019ApJ...871L..16M
    Evolved stars in the Local Group galaxies - III. AGB and RSG stars in Sextans A 2019MNRAS.482.4733D
    Measuring the expansion and age of the nova shell IPHASX J210204.7 + 471015 2019MNRAS.483.3773S