Skis, snow, and supernovae

Posted by Rich Talcott
on Thursday, February 22, 2007
The Sun shone brightly on the snowy slopes of
Aspen during this week’s supernova workshop.
But the participants, including your humble
correspondent, were more interested in exploding
stars. Larry Marschall

With 12 inches of fresh powder on the slopes at Aspen, you might think everyone at this week's supernova workshop would be grabbing their skis or snowboards, donning their parkas, and heading off to one of the town's four mountains. You obviously don't know astronomers. Given a choice between skiing and talking astrophysics, most would choose the latter. (Although, truth be told, long lunch breaks leave open the possibility of talking and skiing. Some astronomers reportedly chewed gum at the same time.)

Approximately 100 astronomers from around the world have gathered at the Aspen Center for Physics to participate in "Supernova 1987A: 20 years after — Supernovae and gamma-ray bursters." This week marks the 20th anniversary of when light from an exploding star in the Large Magellanic Cloud first reached Earth. As the closest known supernova since the invention of the telescope, 1987A became a proving ground for theories about how stars explode and how they behave afterward.

The theories didn't fare all that well. First, the exploding star happened to a blue supergiant, not a red supergiant as most everyone expected. Second, the supernova didn't reach its peak brightness for nearly 3 months — far longer than most supernovae of its type take.

Astronomers have answered many of the questions 1987A raised about supernovae, but a slew more have arisen in the 20 years since. The first 2 days of the workshop looked at the history, evolution, and current observations of the developing supernova remnant.

Next, the discussion turned to supernovae in general. Surprisingly, perhaps, theorists still haven't figured out exactly how core-collapse supernovae (like 1987A) occur. Even the best computers today can't do the 3-D simulations needed to answer the question.

The cosmologists here are more interested in supernovae arising from the thermonuclear detonations of white dwarfs. These beacons helped astronomers realize that a mysterious force, called dark energy, pervades the universe and is causing cosmic expansion to accelerate. But more observations are needed to pin down exactly what dark energy means for the future of the universe.

By the end of the week, we'll have moved on to gamma-ray bursts (GRBs) and their sources. Some of these explosions occur in concert with supernovae, some do not. GRBs release even more energy than supernovae, however, so they fire the passions of observers and theorists alike.

The supernova workshop brings together top researchers to discuss their latest results and plan future efforts. During the next few months in this blog, I'll return occasionally to the workshop's topics, to keep you current on one of astronomy's most exciting subjects.

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