LONG-LIVED GIANT-CELLS DETECTED AT THE SURFACE OF THE SUN

Giant convective cells have been predicted(1) to exist in the Sun. Suc h cells should span the entire zone unstable to convective motions-now known to cover the outer 29 per cent of the Sun's radius(2)-and could be dredging up the magnetic flux that is thought to be the source of solar activity (sunspots). Several studies(3-5) have failed to detect these giant cells, although there have been hints(6-9) of their existe nce. We have detected long-lived velocity cells, which we identify as the elusive giant convective cells, extending over 40-50 degrees of lo ngitude but less than 10 degrees of latitude. The large aspect ratio ( >4) is surprising (although predicted by one model(10)) and may be a c onsequence of the Sun's differential rotation, whereby features with a larger extent in latitude are broken up by rotational shear.