Models for the progenitor systems of Type Ia supernovae can be divided into double-degenerate systems , which contain two white dwarfs , and single-degenerate systems , which contain one white dwarf plus one companion star ( either a red giant , a subgiant , or a > 1.16 M _ { \odot } main sequence star ) .
The white dwarf is destroyed in the supernova explosion , but any non-degenerate companion remains intact .
We present the results of a search for an ex-companion star in SNR 0519-69.0 , located in the Large Magellanic Cloud , based on images taken with the Hubble Space Telescope with a limiting magnitude of V = 26.05 .
SNR 0519-69.0 is confidently known to be from a Type Ia supernova based on its light echoes and X-ray spectra .
The geometric center of the remnant ( based on the H \alpha and X-ray shell ) is at 05:19:34.83 , -69:02:06.92 ( J2000 ) .
Accounting for the measurement uncertainties , the orbital velocity , and the kick velocity , any ex-companion star must be within 4.7 \arcsec of this position at the 99.73 % confidence level .
This circle contains 27 main sequence stars brighter than V = 22.7 , any one of which could be the ex-companion star left over from a supersoft source progenitor system .
The circle contains no post-main sequence stars , and this rules out the possibility of all other published single-degenerate progenitor classes ( including symbiotic stars , recurrent novae , helium donors , and the spin-up/spin-down models ) for this particular supernova .
The only remaining possibility is that SNR 0519-69.0 was formed from either a supersoft source or a double-degenerate progenitor system .