Dust to Dust: Three Years in the Evolution of the Unusual Sn 2008s

We obtained late-time optical and near-IR imaging of SN 2008S with the Large Binocular Telescope, near-IR data with the Hubble Space Telescope , and mid-IR data with the Spitzer Space Telescope . We find that (1) it is again invisible at optical ( UBVR ) wavelengths to magnitude limits of approximately 25 mag, (2) while detected in the near-IR ( H ) at approximately 24.8 mag, it is fading rapidly, and (3) it is still brighter than the progenitor at 3.6 and 4.5 μm in the mid-IR with a slow, steady decline. The IR detections in 2010 December are consistent with dust emission at a blackbody temperature of T ≃ 640 K and a total luminosity of L ≃ 200,000 L ☉ , much higher than the L ≃ 40,000 L ☉ luminosity of the obscured progenitor star. The local environment also shows no evidence for stars significantly more massive than 10 M ☉ , consistent with the progenitor being an 8–10 M ☉ super asymptotic giant branch star.