Decay of sunspots

The photometric decay of sunspots is studied in some detail. Aspects related to leader vs. follower sunspot decay are presented and our current understanding of the physical mechanisms involved critically reviewed. The intrinsic instability of follower spots to form a stable sunspot cannot be understood in terms (if the fluting stability as proposed long time ago. For leader sunspots, the slow decay phase is considered in the light of diffusive models that spread the flux of the spot over a larger area. It is shown that the Moving Magnetic Feature (MMF) phenomenon, while probably part of the decay process, has an origin not related to the decay process itself. Magnetic flux losses from leader sunspots are 3 to 8 times slower than the pace of net flux generation seen in the moat region. It is argued that MMFs are originated front the interaction of the field free convection (moat flows) and the Evershed magnetized channels outside the spot.