Nucleosynthesis and molecular processes in evolved stars

Most of the stars (M < 8 solar masses) in the Universe end their lives with a phase of strong mass loss and experience thermal pulses (TP) on the Asymptotic Giant Branch (AGB), just before they form Planetary Nebulae (PNe). They are one of the main contributors to the enrichment of the interstellar medium and thus to the chemical evolution of galaxies. More
specifically, the more massive AGB stars form very different isotopes (such as 87Rb, 7Li, 14N) from the isotopes formed by lower mass AGB stars and Supernova explosions, as a consequence of different dominant nuclear reaction mechanisms. Stars evolving from the AGB phase to the PN stage also form complex organic molecules (such as polycyclic aromatic hydrocarbons and fullerenes) and inorganic solid-state compounds. The ~100-10,000 years of evolution following the end of the AGB phase represents a most fascinating laboratory for Astrochemistry. I will present some of my recent findings in this field such as the recent identification of "super Li-rich" massive AGBs at the beginning of the TP phase as well as the detection of complex carbon-based molecules like fullerenes, graphene, and molecular-related species in the circumstellar shells of PNe.

23/01/2014 - 13:30
Dr. Anibal García Hernández