In a new paper in Astronomy & Astrophysics, a team of Max Planck Institute for Astrophysics researchers led by Maria Bergemann look at how the abundance manganese has changed over the course of history, with generations of supernova adding it into the universe. In their study of chemical abundances, they find that the ratio of manganese to iron stays with time. Since these two elements are created in very different ways, this means that on average, the processes that produce 1 happen as often as the methods that produce the other, like two different factories working on similar production schedules. In looking at all the different ways that manganese can be formed, they realized the only way they could explain their observations is ¾ of all type 1a supernovae – explosions of white dwarf stars – that have occurred in our galaxy of its history were non-standard supernovae.

When we normally talk about Type 1a supernova, we assume a system where a moon-sized white dwarf if orbiting a giant star and slurping off its outer atmosphere with gravity. When the white dwarf star has consumed enough of its neighbor to top 1.4 solar masses, it explodes. This is because the white dwarf can’t support that much matter. But, as we’ve recently pointed out, white dwarfs can find other ways to go boom. They can merge into their companion star, triggering a double detonation as both stars destabilize. They can merge with another white dwarf. Well, the can merge pretty much with whatever they please, and in each of these myriad scenarios they can go supernova and they will often detonate their companion’s core as they go. This new research finds the chemistry of our galaxy is consistent with these double detonations being the donate death explosion of white dwarfs. If this is the case, then our measurements of the expansion of the universe are based solidly on a false assumption about the nature of type 1a supernovae.

Research like this requires replication, and a team at CalTech has already started to see similar results in looking at stars in dwarf galaxies. The next Gaia mission data release should help them identify white dwarf binary systems, and directly determine how common these small dense systems may be. For now, this is one more observational line of evidence indicating we don’t understand our universe as well as we thought we did, and dark energy may someday be the thing our generation of astronomers is laughed at for theorizing… at least one can hope. 

Link to Press Release