Title: Dust and the Late-Time Evolution of Type II Supernovae
Abstract: We propose to continue our program to study the evolution of Type II supernova spectra and near-IR brightness at late times, 1-3 years after the initial explosion when dust typically condenses in the ejecta. Dust formation can be observed in the development of asymmetric, blue-shifted, emission-line profiles and from an increase in IR luminosity. These are caused by new warm dust clouds radiating and preferentially extinguishing redshifted emission from the far side of the expanding ejecta. Therefore, we are proposing to obtain new GMOS-N spectroscopy and NIRI near-IR photometry of five important type II SNe, four of which have been detected by the IRAC instrument on the Spitzer Space Telescope. We propose to multiply the usefulness of other existing and proposed datasets by obtaining late-time spectra and photometry of these SNe covering the important time period of dust formation. One observation will be obtained for each of the five SNe with each of GMOS-N and NIRI.
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