Effects of Different Magnetic Structures within the Photosphere on Granulation

Abstract

Using the high-resolution data in the TiO band taken by the 1 m New Vacuum Solar Telescope (NVST) at the Fuxian Lake Solar Observatory (FSO), we statistically investigated the effects of different magnetic field structures within the photosphere on granules via the newly developed algorithms for identifying granules. The data of NVST have much higher contrast (9.6%), therefore which is helpful for identifying smaller granules and performing more detailed analyses and studies than before. It is found that two critical scales of granules, D1 and D2, exist, and that the probability density of the equivalent diameter of granules with scales smaller than D1 follows a power law distribution similar to the Kolmogorov spectrum. We classify granules into three groups of different origins: the granules smaller than D1 are turbulent, those larger than D2 are convective, and those with scales between D1 and D2 result from blending of turbulence and convection, which is an intermediate case of the two formers. Meanwhile, we also noticed that the different magnetic field structures within the photosphere impact the critical scale, D1, of the turbulent granule in an apparent way such that the stronger the nearby magnetic field is, the smaller the value of D1 is. On the other hand, magnetic field imposes almost no effect on the mean radiative intensity of its external granules and the corresponding distribution features.