Scale height of different baryonic disks in NGC 551 under hydrostatic equilibrium. The left, middle, and right panels represent scale heights for the stellar, molecular, and atomic disks, respectively. The solid lines in each panel represent the scale height due to our iterative method, whereas the dashed lines show the scale heights for the analytically calculated σ_⋆. The vertical dashed line in the left panel indicates the scale length of the stellar disk (4.6 kpc). The analytically calculated σ_⋆ overestimates the stellar scale height by more than a factor of two, giving the false impression of a thick stellar disk.