The Statistical Study on the Size Distribution of Disk Galaxies

We chose 40599 face-on disk galaxies from Data Release 4 of Sloan Digital Sky Survey and statistically investigated their sizes. It is shown that the sizes distribution of disk galaxies at the given abosolute magnitude is well described by a log-normal function for late-type galaxies. There is a tight relation between the size of galaxies and the abosolute magnitude. that is, the bigger the brighter. We also compared our results with shen et al. (2003) in the same abosolute magnitude bin, Our results show that the half-light radii in r band is little higher than theirs. Because our samples are only for face-on late-type galaxies while theirs included all late-type galaxies.