Differential rotation of photospheric magnetic fields associated with coronal holes

An interesting aspect of solar rotation is the fact that coronal holes seem to exhibit little or no differential rotation. We set out to investigate the question of whether or not the photospheric magnetic fields underlying coronal holes also exhibit reduced differential rotation. In order to accomplish this we measured the daily positions of filaments and plages surrounding a large coronal hole that lasted for several disk passages. The resulting differential rotation curve was considerably flatter than the standard curve for long-lived filaments and was in remarkably good agreement with the curve found for the overlying coronal hole itself.