Nordita, Stockholm, Sweden
The third and fourth week of this program were cancelled, due to covid-19.
Understanding stellar convection is of crucial importance to many fields of stellar astrophysics.
For example, the generation and maintenance of differential rotation and large-scale magnetic fields in stars rely on turbulent convection. However, mounting evidence suggests that our understanding of stellar convection is much more incomplete than previously thought.
The most dramatic manifestation of this is the wide discrepancy between the velocity amplitudes at large horizontal scales from helioseismic inferences and numerical simulations. This constitutes the ‘convective conundrum’ which is arguably the greatest open problem in the field of stellar convection today.
Furthermore, most stellar structure and evolution codes still use outdated local mixing length models to describe convection whereas numerical simulations indicate that non-locality and interactions with rotation and magnetic fields need to be taken into account in realistic parameterizations.
We bring together experts in three-dimensional convection simulations, helio- and asteroseismology, and theoreticians working on replacing the mixing length concept to present the latest developments and to address open problems in the field.
The first three weeks of the program are planned to be dedicated to specific topics with informal presentations/discussions. There will also be time to work on new ideas that often come up as a result of the discussions.
Week 1: Fundamentals.What is the cause of the convection conundrum? Are the numerical simulations lacking essential physics such as more sophisticated treatment of the boundary layers near the surface and the base of the convection zone? Can subgrid-scale models be used to alleviate the resolution issue?
Week 2: Observations. How can numerical convection simulations be used to test and improve the methods of helio- and asteroseiseismology? What can we learn about convection zones and related phenomena of stars other than the Sun using asteroseismology? Is there a way to obtain information about magnetic fields within the solar convection zone?
Week 3: Applications. How can the effects of rotation, magnetic fields, and non-locality be accounted for in 1D parameterizations of convection in stellar evolution codes? Do the more physically consistent models lead to significantly different results in the scope of stellar evolution? Which observational results are the most relevant to constrain parameterizations of convection?