Instead, he and his colleague, Jonay Gonzales Hernandez concluded that the event must have resulted from a collision or merger of two white dwarf stars. Such an event would also produce a supernova explosion - only one that leaves no trace, other than the glowing remnant we see today.
It's kind of cosmically romantic when you think about it: two white dwarf stars, joined by gravity, dying together in a spectacular burst of energy that is seen all over the globe. Compare that to the fate of the companion star in the system that produced Tycho Brahe's supernova of 1572, which the astronomers did find, languishing in stellar widowhood.
Ruiz-Lapuente and Gonzalez Hernandez have studied five supernovae to date, and only once (with SN 1572) have they found a likely companion star. This could mean that merging white dwarfs might be a more common pathway to these types of stellar explosions than previously thought.
Next up in their continued analysis: Kepler's supernova of 1604!
Images: (top) Composite image of SN 1006 remnant, combining x-ray, optical, and radio data. Sources: NASA/Chandra (x-ray); NRAO/AUI/NSF/GBT/VLA (radio); NOAO/AURA/NSF/CTIO (optica). (bottom) Pteroglyph that may (or may not) depict SN 1006. Credit: John Barentine, Apache Point Observatory.