Scientific Rationale

The Sun as a complex hydrodynamic and magnetohydrodynamic object has attracted much investigators’ attention for a few past decades. Modern observational instrumentation onboard orbital observatories such as, e.g., Solar Dynamics Observatory (SDO) currently provide an invaluable abundance of diverse data. Substantial progress has been achieved in theoretical studies of solar convection, differential rotation, meridional circulation, global solar dynamo and local processes of interaction between plasma flows and magnetic fields in the upper convection zone and photosphere, which are responsible for the local phenomena of solar activity. On the other hand, the progress in the development of observational techniques stimulated investigations aimed at understanding the dynamics of stellar plasma. Hydrodynamic and magnetohydrodynamic studies of the Sun and stars demonstrate a remarkable convergence, approaching a unified description of all these objects. In the numerical simulations of convection and magnetoconvection, which have now greatly increased their coverage in the parameter space, the solar-convection regime plays the role of a “reference point” for the set of models. The theories of differential rotation and of global dynamo have now reached a level that allows considering both these constituents of the global dynamics in the framework of a single model. Helioseismology offers a previously unreachable insight into the dynamics of layers hidden from our eyes. The ideas of helioseismology are now being extended to stellar physics, which results in the successful development of asteroseismology.

A particular point of importance is related to magnetic-flux-emergence processes producing active regions and to the link between global and local magnetohydrodynamic processes. The extensive data from, e.g., SDO can be used for detailed analyses and investigations of the underlying physics on the basis of an adequate magnetohydrodynamic description, which is of paramount importance for the elaboration of techniques of active-phenomena predictions.

An important application field of the investigations of solar global-scale processes is related to the prediction of solar-activity cycles. Such predictions will be the more reliable, the more complete our understanding of the global solar dynamics, and the investigation of stellar dynamics may substantially contribute to the completeness of the general view of the physical processes.

Further progress in tackling this multifaceted complex of phenomena requires the coordination of efforts of investigators engaged in different problems, extensive discussions and exchange of views. It is important to pay particular attention to processes in the dense plasma of the solar and stellar convection zones and photospheres, where the complex of active phenomena originates. At the same time, since the photosphere is strongly dynamically coupled with the overlying layers and flows in the convection zone and photosphere may definitely have counterparts in the lower atmosphere, a strict separation between the photosphere and the layers situated immediately above it would not be warranted. For this reason, although the scope of the planned Symposium is mainly focussed on the dynamics of the convection zones and photospheres, it is also meant to encompass those processes in the lower atmospheres that can be regarded as a direct continuation of the processes in the underlying zones.

The forthcoming Symposium will be dedicated to observational and theoretical aspects of solar and stellar hydrodynamics and magnetohydrodynamics, both global and local, with the inclusion of numerical studies as a particular branch of theoretical research. With this scope assumed, the meeting will hopefully stimulate the origin of new ideas and development of new techniques in this topical field of research.

Byurakan Astrophysical Observatory (BAO; Byurakan, Armenia) of National Academy of Sciences of the Republic of Armenia, the venue of the meeting, has a huge experience in organization of such meetings, both in Byurakan and Yerevan, the Capital city of Armenia. Armenia is rich with historical sights and monuments and is rather attractive from the touristic point of view as well.

Contacts: (SOC) (LOC)

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