Recent discoveries suggest that Sun-like stars experience a fundamental shift in their rotation and magnetism around middle-age. We have now identified this transition in the best available data on stellar cycles.
Using a combination of the magnetograms, we find signs of the beginning of the 25th cycle from both HMI and WSO by calculating the inclination angles determined from the variation in line of sight field during a disk passage.
Tiny sunspots, or pores, might have escaped the observers during the Maunder minimum. However, they might have carried enough magnetic flux for the normal operation of a Babcock-Leighton-type dynamo.
Solar inter-network magnetic field, the weakest component of the solar magnetism, seems to be invariant at ~10 G from the minimum to the maximum phase of Cycle 24. This suggests a possible origin of small-scale, local dynamo.
Taking advantage of 11 different databases, we use statistical analysis to probe the nature of photospheric magnetic structures. We find evidence of two separate mechanisms at play, and propose that they are directly connected to the global and small-scale components of the solar dynamo.
Numerical simulations of solar rotation and dynamo have been performed over the last decades with the aim of understanding the physics of the solar interior. Here we briefly discuss two main approaches, namely, mean-field modeling and global simulations. We also present recent results of hydrodynamic global simulations which reveal interesting aspects of stellar rotation.
Motivated by recent observations we have explored whether the flux-transport dynamo model can work with multi-cell meridional flow. We find that it can work when certain conditions are fulfilled.
Solar meridional circulation, if mechanically driven and thermally
braked, contains two cells in latitude; generating two cells in depth,
recently observed by SDO/HMI, is a new challenge to theory.