Illustration of the light-curve degeneracy resulting from the interaction of ejecta with a CSM of 0.024 and 0.28 M_⊙. The initial conditions for the interaction are shown at top left: Case (1) corresponds to a model with a steep atmosphere followed by a dense wind and Case (2) corresponds to a model with a shallow atmosphere followed by a tenuous wind. The resulting bolometric light curves from HERACLES are shown at top right. The following three rows then show the luminosity, the density, and the velocity versus radius for first case (left column; 0.024 M_⊙ of CSM) and the second case (right column; 0.28 M_⊙ of CSM). The dot shows the location of the photosphere as computed in HERACLES.