Long-lived giant cells detected at the surface of the Sun

Abstract

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