This ERC project led to a myriad of new astronomical observations (WP1), maybe most importantly the high-impact ALMA Large Program ATOMIUM (PI Decin). This 3.4 million € project, with~45 international collaborators was the first ALMA Large Program accepted in the broad field of `Stellar evolution and the Sun' and lead to the discovery that stellar and planetary companions shape the winds of almost all evolved stars, and of which the first ground-breaking results were published in Science (Decin et al. 2020). A plethora of other papers based on observations of this ERC project has meanwhile been published or accepted for publication, including the high-impact Nature paper Montargès et al. (2021) on the Great Dimming of Betelgeuse, which reached a wide international audience.
These observations were the basis of a detailed analysis effort (WP2) to constrain the thermodynamic and chemical properties of these environments, allowing us to find new correlations and determine causal effects, thereby shedding new light on the prevailing mechanisms determining the late stages of stellar evolution of low and intermediate mass stars. These results were published in several papers including Danilovich et al. 2018, Van de Sande et al. 2018, Danilovich et al. 2020, Gottlieb et al. 2021.
During this ERC-CoG we developed a novel, worldwide unique, numerical model for simulating the winds of evolved stars (WP3), combining knowledge on (the temporal behavior of) the thermodynamic properties, chemical kinetics, and radiative transfer, and implementing novel ideas based on linear algebra, GPUs and machine learning.It is the combination of these sophisticated models with the rich observational data, which allowed for transformative research. Some relevant papers include Malfait et al. 2021, Maes et al. 2021, De Ceuster et al. 2020, El Mellah et al. 2020, De Ceuster et al. 2020, Van de Sande et al. 2019.
An important part of this project was the study of laboratory and theoretical (quantum)chemistry (WP4), and was mainly executed in collaboration with the colleagues from the University of Leeds. Here we tried to unravel the chemical pathways towards the formation of the first dust seeds in stellar winds, based on results from WP2 and WP3 to dictate the choice of relevant species to be studied. We performed complex quantum-chemical calculations to unravel the geometry and chemical activity of large gaseous clusters, being precursors of the dust grains. These theoretical calculations were complemented with laboratory experiments to determine the reaction rate coefficients at varying temperatures. Example publications include Mangan T. et al.; Gobrecht et al. 2021, Gobrecht et al. 2021, West N. et al. 2019.
This interdisciplinary approach, including collaboration with students and senior scientists from physics, chemistry, mathematics, computational sciences, and engineering sciences, proved invaluable, and made this ERC-CoG so successful, resulting in 70 peer-reviewed journal publications, including high-impact publications in flagship journals such as Science, Nature, Nature Astronomy, and Annual Review of Astronomy & Astrophysics.
