DISPERSAL OF G-BAND BRIGHT POINTS AT DIFFERENT LONGITUDINAL MAGNETIC FIELD STRENGTHS

Abstract

G-band bright points (GBPs) are thought to be the foot-points of magnetic\nflux tubes. The aim of this paper is to investigate the relation between the\ndiffusion regimes of GBPs and the associated longitudinal magnetic field\nstrengths. Two high resolution observations of different magnetized\nenvironments were acquired with the Hinode/Solar Optical Telescope. Each\nobservation was recorded simultaneously with G-band filtergrams and Narrow-band\nFilter Imager (NFI) Stokes I and V images. GBPs are identified and tracked\nautomatically, and then categorized into several groups by their longitudinal\nmagnetic field strengths, which are extracted from the calibrated NFI\nmagnetograms using a point-by-point method. The Lagrangian approach and the\ndistribution of diffusion indices approach are adopted separately to explore\nthe diffusion regime of GBPs for each group. It is found that the values of\ndiffusion index and diffusion coefficient both decrease exponentially with the\nincreasing longitudinal magnetic field strengths whichever approach is used.\nThe empirical formulas deduced from the fitting equations are proposed to\ndescribe these relations. Stronger elements tend to diffuse more slowly than\nweak elements, independently of the magnetic flux of the surrounding medium.\nThis may be because the magnetic energy of stronger elements is not negligible\ncompared with the kinetic energy of the gas, and therefore the flows cannot\nperturb them so easily.Yang\n