Steps Towards a New Generation of Stellar Models

Description and Aim

Theoretical stellar modeling is one of the main tools to investigate the formation and evolution of Galactic and extragalactic stellar systems. The latest generation of astronomical instruments available at ground based and space-based telescopes are delivering increasingly large amounts of observations with unprecedented accuracy, and new windows are being opened by recent space-based accurate asteroseismological observations of large samples of stars covering a range of evolutionary phases.

The theoretical interpretation of this steady flow of high-precision and large-volume data requires an increased accuracy of the predictions of stellar model theory.

The current generation of 1D stellar models is limited by some long-standing, well-known shortcomings that need to be addressed systematically in order to achieve the degree of realism needed to match the present accuracy of the observations. This workshop will bring together experts in traditional stellar evolution modeling and experts in the (magneto-) hydrodynamic simulations relevant for stellar interior conditions. The goal is to develop a consensus on the questions of most urgent concern for stellar evolution calculations, discuss methods and strategies to address them, and to define a roadmap towards the creation of the next generation of stellar models that can meet the new observational challenges. Focus of the workshop is thus mainly theoretical in nature, but we also welcome the participation of observers to help in defining the most urgent problems, and the levels of accuracy and precision needed for the interpretation of present and upcoming astronomical data. We aim at developing strategies that allow the hydrodynamics community to design specific simulations that are identified as being crucial for the 1D-models. At the same time, new descriptions are to be developed to translate insights from multi-D results into practical implementations in 1D stellar evolution models. The prospects of developing a useful, effective multi-D stellar evolution code are to be evaluated, along with methods for coupling 1D-models (treating the global problem on nuclear timescales) to 3D-snapshots (dealing with isolated, spatially and temporally restricted phases). The meeting will consist of review talks summarizing the state-of-the-art of standard 1D stellar evolution codes, the available results from multi-D hydro-simulations, and the challenges posed to current standard stellar models by the observational requirements. Specific talks about efforts to improve the current standards will be contributed by scientists actively pursuing this. Discussion sessions are planned to develop lists of cases to be investigated in 2D/3D, to develop strategies for useful multi-D calculations and for improved physical models, and to develop schemes to improve 1D-models by using existing or future multi-D results.