Discovery of the Dust-Enshrouded Progenitor of SN 2008S with Spitzer
J.L. Prieto, M.D. Kistler, T.A. Thompson, H. Yuksel, C.S. Kochanek, K.Z. Stanek, J.F. Beacom, P. Martini, A. Pasquali, J. Bechtold
ABSTRACT
We report the discovery of the progenitor of the recent type IIn SN 2008S in the nearby galaxy NGC 6946. Surprisingly, it was not found in deep, pre-explosion optical images of its host galaxy taken with the Large Binocular Telescope, but only through examination of archival Spitzer mid-IR data. A source coincident with the SN 2008S position is clearly detected in the 4.5, 5.8, and 8.0 micron IRAC bands, showing no evident variability in the three years prior to the explosion, yet is undetected at 3.6 and 24 micron. The distinct presence of ~440 K dust, along with stringent LBT limits on the optical fluxes, suggests that the progenitor of SN 2008S was engulfed in a shroud of its own dust. The inferred luminosity of 3.5x10^4 Lsun implies a modest mass of ~10 Msun. We conclude that objects like SN 2008S are not exclusively associated with the deaths or outbursts of very massive eta Carinae-like objects. This conclusion holds based solely on the optical flux limits even if our identification of the progenitor with the mid-IR source is incorrect.
Links to the astro-ph version and ADS: arXiv:0803.0324 ADS
Press Release Story in Spitzer website [June 23, 2008]
Circular about the Spitzer detection of the progenitor of the luminous transient in NGC300, an object similar to SN 2008S
Detection of the luminous transient in M85 (2006-M85-OT1) in archival Spitzer data and re-interpretation as the explosion/eruption of a massive star: see this website