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 upcoming space-based facilities such as the 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, we aim at using the GALEX database to discover binary central stars in Galactic PNe.
Members of the project
Highlights and results
1. During 2019, we have published 33 papers in high-impact international refereed astronomical journals and 2 papers in the Chemistry -Physics journal FNCN.
2. Detection of wide binary systems around extreme massive AGB stars has solved the decades-old conundrum about the extreme superwind in these stars.
3. Improvement of the TiO linelist, which will help the modelling of cool stars as well as the detection of exoplanets around M-dwarfs by the cross-correlation technique.
4. Evolved stars (AGB and post-AGB) with double chemistry (rich in C and O) have been discovered for the first time in the Large Magellanic Cloud.
5. It was found that the central star of the planetary nebula NGC 2346, has gone through the phase of "common envelope".
Solid state radiolysis of amino acids in an astrochemical perspective
The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatoryCataldo, Franco et al.
EPOXI: Comet 103P/Hartley 2 Observations from a Worldwide Campaign
Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is smallMeech, K. J. et al.
A Detailed look at Chemical Abundances in Magellanic Cloud Planetary Nebulae. I. The Small Magellanic Cloud
We present an analysis of elemental abundances of He, N, O, Ne, S, and Ar in Magellanic Cloud planetary nebulae (PNe) and focus initially on 14 PNe in the Small Magellanic Cloud (SMC). We derive the abundances from a combination of deep, high-dispersion optical spectra, as well as mid-infrared (IR) spectra from the Spitzer Space Telescope. AShaw, Richard A. et al.