ИСТИНА

Edge-on Disk Galaxies In SDSS (EGIS) is a visually inspected sample of about six thousand true edge-on galaxies identified in the Sloan Digital Survey images. The large sample helps identify statistically valuable subsamples of rare objects. Some sixty galaxies in the catalog have super-thin stellar disks with the radial-to-vertical scale ratio greater than 10. We analyze conditions necessary for the creation of the super-thin disks. While a heavy dark matter halo is necessary to keep stellar disks very thin, the axis ratio range of the super-thin disks in our sample also suggests that the star formation doesn't start below certain fixed threshold surface density.