Evolved cool stars are major cosmic engines, providing strong mechanical, chemical, and radiative feedback on their host environment. Through strong stellar winds, still poorly understood, they enrich their environment with chemical elements, which are the building blocks of planets and life. These objects are known to propel strong stellar winds that carry the mass and angular momentum of the stars' surfaces at speeds that vary with stellar brightness, evolution phase and chemical composition. A complete understanding of their evolution in the near and distant Universe can only be achieved with a detailed knowledge of wind physics across the life cycle of these stars as well as in relation to their circumstellar environment. Our project PEPPER aims at building a coherent and comprehensive description of the mass-loss mechanism.
The main questions we endeavour to tackle are: How are the winds launched and which physical processes determine their properties? How does the mass-loss rate and other wind properties depend on fundamental stellar parameters? What is the origin of the detected magnetic field on the stellar surface? What chemical processes dominate in the winds? Where does the interaction between dynamics and chemical phenomena lay?
The core of our approach is the synergy between theory and observation. During the ANR project, current and future developments of 3D simulations will be used to explore and interpret all the observations made with different techniques in order to obtain a global, coherent vision of the evolved cool stars, from the bottom of the atmosphere up to the circumstellar environment.
In order to reliably and significantly achieve this significant milestone, we request funding to support PEPPER members and ensure the project is staffed adequately to yield high-impact scientific returns in the field of evolved stars. PEPPER consortium includes four nodes in France which represent all the poles where stellar physics and, in particular, evolved stars are actively studied simultaneously from an observational, theoretical, or instrumental point of view. To complement this team, we request for funding for two PhD students and three postdoctoral researchers who will be spread over the four French nodes of our project, along with funds to support and secure the visibility and active partnership of all French team members.