Distribution of sunspot groups from asymmetric rising flux loops.

Rising magnetic flux loops in the solar convection zone develop an asymmetric shape with a flat preceding part and a steeper following part with respect to the direction of solar rotation. By a statistical analysis of newly forming sunspot groups we test the conjecture that this geometrical asymmetry leads to an asymmetric distribution of secondary spot groups originating from the legs of the same rising flux loop as the primary group, which develops out of the loop summit. We find that ~10% of all sunspot groups actually develop secondary groups within +/-20° longitude distance from the primary group and within one day after its emergence. Those secondary groups related to small primary groups (area <100 millionths of the solar hemisphere) are predominantly located on their eastern (following) side, while for larger primary groups the secondaries are more numerous on their western (preceding) side. Both results are consistent with the geometrical asymmetry developed by rising magnetic flux loops.