Light echoes in RS Pup

In order to better vizualise the light echo phenomenon, the astronomers computed a continuous movie of the progression of the light echoes in the nebula (using a spline interpolation of the measured epochs for each pixel). The variation of the luminosity of RS Pup is visible on these images from the changing extension of the wings of its 'Point Spread Function' (PSF). The morphological changes of the nebula with time are considerable. In these images, the astronomers could monitor at all times the propagation of more than seven echoes, allowing them to determine the distance of the star.