IT'S an embarrassing gap in astronomers' knowledge. Despite relying on type Ia supernovae as tools to measure the dark energy speeding up the universe's expansion, they still don't know exactly what causes the blasts. Now the picture has got even fuzzier."Bwa ha ha ha! Those crazy scientists don't know what's going on! They're all confused because of 'gaps'! Bwa ha ha ha!"
Ugh. This is why I can't stand most science journalism. It takes what's a pretty cool journal article about people figuring out how our universe works and refining our knowledge, and acts like they're a bunch of bumbling morons.
If you didn't follow the link to read the rest of the article, it basically says that a new paper is challenging the long held idea that type Ia supernovae come from white dwarfs pushed over their Chandrasekhar limit (the mass limit for a core before it explodes as a supernova) by mass being dumped on them from a companion star.
The evidence thus far seems to fit pretty well. There's not much hydrogen in the spectra, so we know these supernovae aren't normal stars, still surrounded by their hydrogen atmosphere. The total amount of energy fits well. The shape of the light curve works. We see them in old galaxies which should have lots of white dwarfs.
But the issue now is that recent studies have been indicating that we're seeing them in places with lots of active star formation too. In fact, it's being suggested there's even a correlation between the number of Ia supernovae and the amount of star formation. If that's the case, then this suggests that, at the very least, old dead cores can't be the only way to form Ia supernova.
So what's the "new" explanation? The paper doesn't say. There's a hint at the end effectively saying "stay tuned for paper #2!" but no word on what it's going to say yet.
But what does this all have to do with the part of the article I quoted earlier about the age of the universe?
Regardless of whether or not we know exactly what's causing these supernovae, we still know they're excellent standard candles because we can check them against other distance measuring methods (such as the P-L relation of Cepheids or the Tully-Fisher relation). It doesn't matter if it's an overburdened white dwarf or God letting off cosmic farts. Either way, we've observed that they all have an absolute magnitude of -19.3.
Not knowing exactly what causes type Ia supernovae doesn't change the fact that we know how bright they are! Since that doesn't change it doesn't make any difference on our understanding of the age and size of the universe! Tossing in that gibberish about the size and age of the universe is a complete non-sequitor.
Pritchet, C., Howell, D., & Sullivan, M. (2008). The Progenitors of Type Ia Supernovae The Astrophysical Journal, 683 (1) DOI: 10.1086/591314