Rotation of the Sun, coordinate systems

• Recording.
• PowerPoint presentation. In Czech only.
• Hand-written notes. Look over the notes carefully! When deriving the basics of the differential rotation mechanism on the board I made a few mistakes, which are corrected in the notes. Those mistakes are mostly in exchanging v_φ and v_rot.

• Rotation introduces issues to within the equations of the internal structure. The radial energy transfer equations can't be fulfilled when rotation exists -- the von Zeipel paradox. Meridional circulation solves the problem. Effective mainly at hotter stars (A-type or so), which usually have hot poles.
• Solar meridional circulation exists, but is of a different origin. Turbulent pumping play a role.
• Solar rotation is differential (both in latitude and in depth), is effective only in the convection zone. The radiative interior rotates as a rigid body.
• The measurements are not easy to intepret, different methods yield different results.
• There is a solar cycle related varying component of both the differential rotation (=torsional oscillations) and the meridional circulation. It can be found around activity belts. The model of circulating flows (geostrophic flow) around magnetic regions (low-pressure regions) may provide an explanation. Unfortunately this explanation is problematic at the beginning of the solar cycle, when no sunspots exist and yet, the torsional oscillations are observed.
• There are many coordinate systems being used in solar physics, Carrington coordinate mesh (=rigid rotation) is the reference one.