A study of the intrinsic flatness of disk galaxies

The intrinsic flatness of disk galaxies is very important when calculating their angle of inclinations. Our statistical analysis of 14,988 disk galaxies taken from the Lyon-Meudon Extragalactic Database shows that the intrinsic flatness is closely related to the morphological type. In general, the intrinsic axis ratio q0 is larger for lenticulars and irregulars than for spirals, and among the sprials, is larger for the early types than for the late types. The Scd galaxies are found to have the smallest q0.