Some current problems in helioseismology

Helioseismology is enjoying a tremendous surge of activity, spurred by the combination of reliable data and effective interpretation methods. Since I cannot do justice to the entire field, I attempt in this review to describe two current topics that I find interesting. (1) Several workers have now made measurements relating to the variation of rotation with depth and latitude inside the Sun. Most of the observations agree fairly well on the depth dependence, but not so well on the latitude dependence. I explain how such measurements are made, and discuss the current state of this controversy. (2) The driving mechanism for solar p-modes remains a mystery. The best (in my view) explanation involves stochastic driving of the modes by turbulent convection. This theory (proposed by Goldreich and Keeley) has recently been extended by Goldreich and Kumar in a way that illuminates some issues and obscures others. I attempt to provide a simple introduction to these ideas.