Asymptotic expansion velocities of Type IIP SNe (top), SN "impostors" (middle), and Galactic LBV shells (bottom). The impostor velocities have been corrected for expansion out of the stellar potential well following Equation (33) in order to properly compare them to the LBV shells. The general pattern of the results is not sensitive to the details of this correction. The SNe and the shells require no corrections because of their high velocities and ages, respectively. The curves in the impostor and Galactic LBV panels show the expected distributions for the bins assuming a velocity-dependent rate r( v _shell)∝ v ^−1/3 _shell for 10 km s ⁻¹ < v _shell < 1500 km s ⁻¹ for the impostors and an observable lifetime ∝1/ v _shell for the Galactic shells normalized to the numbers of objects in each panel and excluding SN 1961V.