Couple make a rare find: a supernova ready to flame out

A pair of young astronomers have captured for the first time the earliest death throes of a supernova, verifying a decades-old theory about how these giant stars commit stellar suicide.

While scanning a galaxy 90 million light years away, the soon-to-be-married couple noticed a sudden eruption of X-rays from a spot in the constellation Lynx.

“There was nothing there two days earlier, and now there was this booming object,” said Edo Berger, a 2004 astrophysics graduate of Caltech who now lives in Princeton, N.J., where he is working under a Carnegie-Princeton postdoctoral fellowship.

“As soon as I saw the object, I made a few quick calculations that showed this is nothing we’ve seen before,” Berger said.

Only a certain class of stars, those at least eight times the mass of the sun, are able to generate the star-obliterating power of a supernova. This star, dubbed 2008D, is 30 times the mass of the sun.

When the core of such a star runs out of nuclear fuel, it begins to collapse under its own gravity and becomes a dense neutron star. The neutron star then rebounds, triggering a shock wave that blows the star to bits.

Scientists had predicted that the first thing to escape the shock wave would be an X-ray burst, but none had ever been recorded. All previous, normal supernovae had been discovered only later in the process, when the flash of brilliant light – as bright as the entire galaxy they are in – reaches Earth’s telescopes.

The discovery came Jan. 7, when Berger and his fiance, Alicia Soderberg, both 30, were using NASA’s Swift spacecraft to observe an already discovered supernova in the galaxy NGC 2770.

“I just finished dinner and there was nothing interesting on the TV,” Berger said. “I decided to take a quick look at the observation.”

As soon as he looked at the data coming in from Swift, he saw the new object.

The discovery was the beginning of a frantic quest to confirm the observation.

First, Soderberg, who received her doctorate in astrophysics from Caltech in 2007 and is now also a Carnegie-Princeton fellow, drafted a proposal asking for confirmation from the big Gemini Observatory on Mauna Kea in Hawaii. She also began writing the scientific paper to be published Thursday in the journal Nature.

“I didn’t sleep for a week,” Soderberg said.

Berger predicted this discovery will change the way supernovae are studied. “It turns out that there is a lot more information that can be obtained,” he said.

Some critics have called the discovery a matter of luck. But Sonoma State University astronomer Lynn Cominsky said it’s more than that. “Luck comes to those who are prepared.”

The couple plan to be married next year.

 john.johnson@latimes.com