Our project PEPPER aims at building a coherent and comprehensive description of the mass- loss mechanism in cool and evolved stars. The core of the project is the synergy between theory and observation. Current and future developments, during the ANR project, of the 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.




The main questions we endeavour to solve, together with our objectives, are:

  • How are the winds launched and which physical processes determine their properties?

- We aim at developing and computing a grid of 3D simulations of evolved stars for different stellar                 parameters to cover the parameters space of the observations.

- We will work on the observational validation of 3D simulations using a coupled approach based on interferometry and spectropolarimetry for a number of prototypical objects with different stellar parameters.

- We will provide a global view of the velocity field associated to the convection using the tomography technique for a series of stellar objects

  • How do the mass-loss rate and other wind properties depend on fundamental stellar parameters?

- We will provide observational constraints (from Visible and nearIR spectropolarimeters) to resolve the magnetic field in the stellar atmosphere and to trace and follow time evolution of surface anisotropies associated to convection. 

- We will define and apply new atomic and molecular diagnostics to fully exploit Visible and nearIR spectropolarimetric data

  • What is the origin of the detected magnetic field on the stellar surface?

- We will characterize the magnetic field to investigate if the convection-related structures are at the origin of the local dynamo process 

  • What chemical processes dominate in the winds?

- We will map the regions of dust formation in the wind and in the more extended CSE to determine the major dust ingredients and constrain their sizes and radial distribution. 

  • Where does the interaction between dynamics and chemical phenomena lay?

- We will study the properties of the escaping material of the CSE (geometry, kinematics, molecular content) and investigate how CSE chemistry varies depending on winds and mass-loss rates.




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