AAS 207th Meeting, 8-12 January 2006
Session 171 Supernovae
Poster, Thursday, 9:20am-4:00pm, January 12, 2006, Exhibit Hall

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[171.20] Does Metallicity Affect the Fate of Massive Stars?

R. Covarrubias, J. Dalcanton (University of Washington), M. Hamuy (Universidad de Chile), A. Clocchiatti (P. Universidad Catolica de Chile)

We are working to answer this question by measuring abundances of HII regions in galaxies that hosted Core Collapse Supernovae (CCSNe), and correlating them with the SN properties. The latter will be derived for 63 nearby (z < 0.08) CCSNe with high quality optical photometry and spectroscopy collected by the CTIO and Carnegie groups between 1986-2003 (mostly since 2001 in the course of the Carnegie Type II Supernova Survey).

Maeder (1992) and Mowlavi et al. (1998) showed that the numbers of the various CCSNe subtypes (Type II, Type Ib, and Type Ic) should depend on the metallicity of the host galaxy. Prantzos & Boissier (2003) recently addressed this issue. Using the metallicity-luminosity relationship for late type galaxies (Garnett 2002 and references therein), they derived global abundances for galaxies which had previously hosted core-collapse SNe and showed that the observed ratio NIb,c/NII between SNe of Type Ib, Ic and II does depend strongly on the metallicity of the host galaxy. Although encouraging, the Prantzos & Boissier study is based only on a crude estimate of the global galaxy abundance and not that of the specific explosion site.

Our goal is to improve upon this previous result by measuring the nebular abundances of the nearest HII region(s) to each SN. Our hypothesis is that these nebular abundances are a better representation of the SN metallicity, and that they should correlate strongly with the supernova properties like spectral type, luminosity, lightcurve shape, ejecta velocity, and the 56Ni mass synthesized in the explosion.

RC acknowledges support by a Grant-In-Aid of Research from the National Academy of Sciences, administered by Sigma Xi, the Scientific Research Society.

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