The Disappearance of the Progenitors of Supernovae 1993J and 2003gd

Using images from the Hubble Space Telescope (HST) and the Gemini Telescope we confirm the disappearance of the progenitors of two Type II supernovae (SNe), and evaluate the presence of other stars associated with them. We find that the progenitor of SN 2003gd, an M-supergiant star, is no longer observed at the SN location, and determine its intrinsic brightness using image subtraction techniques. The progenitor of SN 1993J, a K-supergiant star, is also no longer present, but its B-supergiant binary companion is still observed. The disappearance of the progenitors confirms that these two SNe were produced by Red Supergiants.
Comment: Science, in press, published online 19/03/09, 28 pages (MS+SOM) (high-res figures available at http://www.dark-cosmology.dk/~justyn/research/)