  Type Ia supernovae (SNe Ia) are well-known for their use in the measurement
of cosmological distances, but our continuing lack of concrete knowledge about
their progenitor stars is both a matter of debate and a source of systematic
error. In our attempts to answer this question, we presented unambiguous
evidence that LMC SNR 0509-67.5, the remnant of an SN Ia that exploded in the
Large Magellanic Cloud 400 +/- 50 years ago, did not have any point sources
(stars) near the site of the original supernova explosion, from which we
concluded that this particular supernova must have had a progenitor system
consisting of two white dwarfs (Schaefer & Pagnotta 2012). There is, however,
evidence of nebulosity near the center of the remnant, which could have been
left over detritus from the less massive WD, or could have been a background
galaxy unrelated to the supernova explosion. We obtained long-slit spectra of
the central nebulous region using GMOS on Gemini South to determine which of
these two possibilities is correct. The spectra show H-alpha emission at a
redshift of z = 0.031, which implies that the nebulosity in the center of LMC
SNR 0509-67.5 is a background galaxy, unrelated to the supernova.
