Statistical study of UV bright points and magnetic elements from SDO observations

Abstract

We have investigated the ultraviolet bright points (UVBPs) in 14 quiet regions near the solar disk center observed by Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO) from 19 to 25 in August 2010. Each region has a size of 200×200arcsecs2. In total, 2722 UVBPs at 1600Å and 2963 UVBPs at 1700Å are determined from the bright pixels above the mean value plus three time deviation of the background emission. Each UVBP has a minor size of 25pixels (about 9.3arcsecs2). The frequency distributions of these UVBPs occurrence as functions of brightness and size (area) exhibit a power-law behavior, i.e. dN/dx∝x-αx, with an index of αB=1.91±0.03 at 1600Å and αB=1.87±0.02 at 1700Å for the brightness, and of αS=1.95±0.03 at 1600Å and αS=2.01±0.03 at 1700Å for the size. We find that these UVBPs show a South–East direction orientation (θ) on the solar disk, whatever on the northern or southern hemispheres. We also find that the UVBPs are strongly related to the magnetic elements, which are identified from Helioseismic and Magnetic Imager (HMI) observations, indicating that the UVBPs origination from the magnetic elements.