SN 2008S erupted in early 2008 in the grand design spiral galaxy NGC 6946 .
The progenitor was detected by Prieto et al .
in Spitzer Space Telescope images taken over the four years prior to the explosion , but was not detected in deep optical images , from which they inferred a self-obscured object with a mass of about 10M _ { \odot } .
We obtained Spitzer observations of SN 2008S five days after its discovery , as well as coordinated Gemini and Spitzer optical and infrared observations six months after its outburst .

We have constructed radiative transfer dust models for the object before and after the outburst , using the same r ^ { -2 } density distribution of pre-existing amorphous carbon grains for all epochs and taking light-travel time effects into account .
We rule out silicate grains as a significant component of the dust around SN 2008S .
The inner radius of the dust shell moved outwards from its pre-outburst value of 85 AU to a post-outburst value of 1250 AU , attributable to grain vaporisation by the light flash from SN 2008S .
Although this caused the circumstellar extinction to decrease from A _ { V } = 15 before the outburst to 0.8 after the outburst , we estimate that less than 2 % of the overall circumstellar dust mass was destroyed .

The total mass-loss rate from the progenitor star is estimated to have been 0.5-1.0 \times 10 ^ { -4 } M _ { \odot } yr ^ { -1 } .
The derived dust mass-loss rate of 5 \times 10 ^ { -7 } M _ { \odot } yr ^ { -1 } implies a total dust injection into the ISM of up to 0.01 M _ { \odot } over the suggested duration of the self-obscured phase .
We consider the potential contribution of objects like SN 2008S to the dust enrichment of galaxies .