Last month, astronomers announced that one of the most famous supernovae, SN 1006, may have resulted from a collision or merger of two white dwarf stars (a "double-degenerate" model). Such an event would also produce a supernova explosion - only one that leaves no trace, other than the glowing remnant we see today.
Wheeler has proposed a third option, asserting that observational data of actual Type 1a supernovae don't support either of those two models satisfactorily. Specifically, current models of supernova spectra - the light signatures from these very bright stars - as they change over time don't match the data from actual supernovae.
So Wheeler suggests a modification of the first model is needed, in which a white dwarf pairs with a so-called M dwarf star in a binary system.
M dwarfs are quite common, but they are also very dim, and might not be detected by the large telescopes astronomers use to observe the remnants that remain after a supernova explosion. "One thing blows up as a supernova, the other thing's got to be left behind," Wheeler said via press release. "Where is it? We don't see it."