We report the successful identification of the type of the supernova responsible for the supernova remnant SNR 0509-675 in the Large Magellanic Cloud (LMC) using Gemini spectra of surrounding light echoes. The ability to classify outbursts associated with centuries-old remnants provides a new window into several aspects of supernova research and is likely to be successful in providing new constraints on additional LMC supernovae as well as their historical counterparts in the Milky Way Galaxy (MWG). The combined spectrum of echo light from SNR 0509-675 shows broad emission and absorption lines consistent with a supernova (SN) spectrum. We create a spectral library consisting of 26 SNe Ia and 6 SN Ib/c that are time-integrated, dust-scattered by LMC dust, and reddened by the LMC and MWG. We fit these SN templates to the observed light echo spectrum using χ2 minimization as well as correlation techniques, and we find that overluminous 91T-like SNe Ia with \dm15<0.9 match the observed spectrum best.
@article{arxiv.0801.4762,
title = {Spectral Identification of an Ancient Supernova using Light Echoes in the LMC},
author = {A. Rest and T. Matheson and S. Blondin and M. Bergmann and D. L. Welch and N. B. Suntzeff and R. C. Smith and K. Olsen and J. L. Prieto and A. Garg and P. Challis and C. Stubbs and M. Hicken and M. Modjaz and W. M. Wood-Vasey and A. Zenteno and G. Damke and A. Newman and M. Huber and K. H. Cook and S. Nikolaev and A. C. Becker and A. Miceli and R. Covarrubias and L. Morelli and G. Pignata and A. Clocchiatti and D. Minniti and R. J. Foley},
journal= {arXiv preprint arXiv:0801.4762},
year = {2009}
}