A Spitzer Space Telescope Study of SN 2003gd: Still No Direct Evidence that Core-Collapse Supernovae are Major Dust Factories

TL;DR

This study analyzes mid-infrared observations of SN 2003gd, finding limited evidence for newly formed dust in the ejecta and suggesting that core-collapse supernovae may not be major dust producers.

Contribution

It provides a detailed re-evaluation of mid-IR data, challenging previous claims of significant dust formation in SN 2003gd's ejecta.

Findings

Limited dust formation detected (~4 x 10^-5 M_solar)

Mid-IR emission likely from IR echo, not ejecta

No direct evidence of supernovae as major dust factories

Abstract

We present a new, detailed analysis of late-time mid-infrared (IR) observations of the Type II-P supernova (SN) 2003gd. At about 16 months after the explosion, the mid-IR flux is consistent with emission from 4 x 10^(-5) M(solar) of newly condensed dust in the ejecta. At 22 months emission from point-like sources close to the SN position was detected at 8 microns and 24 microns. By 42 months the 24 micron flux had faded. Considerations of luminosity and source size rule out the ejecta of SN 2003gd as the main origin of the emission at 22 months. A possible alternative explanation for the emission at this later epoch is an IR echo from pre-existing circumstellar or interstellar dust. We conclude that, contrary to the claim of Sugerman et al. (2006, Science, 313, 196), the mid-IR emission from SN 2003gd does not support the presence of 0.02 M(solar) of newly formed dust in the ejecta. There is, as yet, no direct evidence that core-collapse supernovae are major dust factories.