Infrared supernova light curves and asymmetric stellar mass loss

Infrared dust emission echos from Type II supernovae are a natural consequence of the heating of circumstellar dust by the supernova light. Red supergiants, the likely progenitors of most Type II supernovae, are known in some cases to have asymmetric circumstellar envelopes. It is noted that an asymmetric dust distribution can have a substantial effect on the evolution of an infrared echo and results are presented for an ellipsoidal dust distribution. The angle between the symmetry axis and the line of sight is unknown in any particular case so that detailed observations of a number of supernovae will be necessary to test for asymmetries. Asymmetries may also be observable in the radio structure of supernovae and in a possible scattered-light echo.