Spitzer Space Telescope - General Observer Proposal #50534


Dust Production in Type II SNe

Principal Investigator: Jennifer Andrews
           Institution: Louisiana State University

     Technical Contact: Jennifer Andrews, Louisiana State University

Co-Investigators: 
Geoffrey Clayton, Louisiana State University                          
Karl Gordon, STScI                                                    
Ben Sugerman, Goucher College                                         
Doug Welch, McMaster University                                       
Margaret Meixner, STScI                                               
Mike Barlow, University College London                                
Barbara Ercolano, Harvard Smithstonian Center for Astrophysics        

Science Category: nearby galaxies (z<0.05, v_sys<15,000 km/s) 
 Observing Modes: IracMap 
  Hours Approved: 4.8 

Abstract:
Recent detection of large amounts of dust in high redshift galaxies has led to
an increased interest in the importance of Type II supernovae (SNe) as dust
producers. The dust in high-z galaxies must come from young, massive stars, so
Type II SNe are one of the few possible sources. We propose to observe three
very bright Type II SNe (SN 2007it, 2007oc and 2007od) in nearby galaxies. The
ages of these SNe mean that they will be perfectly timed to be in their dust
formation phases during Cycle 5. Three observational signatures of this dust
formation can be seen, a decrease in the continuum brightness in the visible, a
developing infrared excess, and asymmetric, blue-shifted emission-line profiles.
We are already planning photometric and spectroscopic observations of these SNe
with Gemini and SMARTS, but observations of the IR emission are needed to
confirm that dust formation has occurred. These three indicators usually appear
around 300-600 days after the SN explosion, when the brightness of the SN has
diminished considerably. Fortunately, these three SNe are all unusually bright,
allowing us a rare opportunity to follow them through and beyond their dust
formation phases. With Spitzer, we will be able to carefully study the IR
emission, and together with the Gemini and SMARTS data, we may be able to double
the number of Type II SNe known to have shown all three dust formation
signatures. This increased sample size will help answer what fraction of Type II
SNe produce dust, how much dust they produce, and what conditions of the SNe
ejecta affect the dust formation. These estimates will put strong constraints on
the formation of dust seen in young, high redshift galaxies.