Abstract

Evolved Stars in the JWST Era

Jeronimo Bernard-Salas (The Open University)

M. Barlow (UCL), A. A. Zijlstra (University of Manchester), J. Th. van Loon (Keele University), J. Cami (UWO, SETI), E. Peeters (UWO, SETI), and the 'Evolved Stars in the JWST Era' working group

The last phases of stellar evolution are a critical stage in a star's life. By the ejection of the outer layers, evolved stars enrich the ISM with dust and gas. The detection of dust at high-redshift has raised many questions about its origin (Asymptotic Giant Branch stars AGBs, Red Super Giants RSGs, super novae, other) and its composition across all redshifts. At least half of all ISM dust in the Local Universe is produced by Asymptotic Giant Branch stars, where more than 60 molecular species have been detected in their outflows. These stars are the source of the main organic species we see in space today including PAHs, which are ubiquitous in the Universe, and fullerenes, the largest molecules identified in space and recently firmly established as the carrier of two Diffuse Interstellar Bands. At the Planetary Nebula (PN) stage they offer for easy but powerful abundances measurements, providing the first view to the results of stellar nucleosynthesis. Since they are visible out to very large distances, PN are ideal kinematic tracers of stellar populations, including areas where there is little or no young stellar population, and the morphologies point to the physics of the ejection process, affected by rotation, binarity and magnetic fields. The past decades have witnessed the detection of a rich and complex molecular inventory produced by these stars, and the production of the first extragalactic census of dust production from evolved stars (including AGBs, RSGs, and super nova). With its capabilities, JWST is ideally placed to revolutionise our understanding of this last phases of stellar evolution. It will allow us to, for the first time, spatially resolve and locate the emission of many molecular species providing key insights into their formation and evolution as a function o the local physical conditions, including the elusive phase where PAHs form. With its sensitivity JWST will push the detection limit of these stars to the Local Group, covering a wide range of environments, and providing a comprehensive survey of dust production in the Universe (see Boyer et al. presented in this conference). In this presentation, and as part of an international working group on evolved stars, we will review the current challenges and describe the unique opportunities that JWST will provide in this field.

Mode of presentation: poster