Thursday, September 21, 2006


Uh-oh, trouble in cosmologyland: Type Ia supernovae, the objects responsible for the post-1998 consensus that the universe is not just expanding, but accelerating, aren't such standard candles after all:
Now, astronomers led by Andrew Howell of the University of Toronto in Canada have found a type Ia supernova that is 2.2 times as bright as others of its class. Called SNLS-03D3bb, it lies about 3 billion light years away, a distance that was independently verified by studying the light spectrum of its host galaxy.

That brightness, along with other clues from the supernova's spectrum, suggests the white dwarf exploded with 2.1 solar masses of material – significantly above the Chandrasekhar mass. "It wasn't a little bit over – it was way over," Howell told New Scientist. "We're forced to say it's not a measurement error."
As a student, I found it amazing that you could use brightness to measure distance. One always suspects that it's harder than it looks, but it's quite impressive that they have sufficient precision to detect outliers. Unfortunately, once everyone trying to image the dynamics of a younger universe gets on board, they're probably going to have a fun time agreeing on just who the "rogues" really are.
These young galaxies are found more often in the early universe, which corresponds to greater distances from Earth. "This might actually improve our precision in future studies if we identify this little subset of supernovae," says Howell.
In my kind of physics, we sometimes call such things "pentaquarks". Ouch.

(Thanks to slashdot, apologies to Brian de Palma for post title...)

1 comment:

Anonymous said...

Notice how this high mass is right in line with the double star merger paradigm advocated by John Middleditch: