Extraordinarily Bright Supernova: A Glimpse of the Early Universe

A super-bright, long-lasting supernova turns out to be the first example of stars that populated the universe.
Extraordinarily Bright Supernova: A Glimpse of the Early Universe
Instead of turning into a black hole after the explosion, SN 2007bi went through a nuclear runaway, making it visible. (Courtesy of DOE/Lawrence Berkeley National Laboratory)
12/13/2009
Updated:
10/1/2015
<a><img src="https://www.theepochtimes.com/assets/uploads/2015/09/091202153939Nova.jpg" alt="Instead of turning into a black hole after the explosion, SN 2007bi went through a nuclear runaway, making it visible. (Courtesy of DOE/Lawrence Berkeley National Laboratory)" title="Instead of turning into a black hole after the explosion, SN 2007bi went through a nuclear runaway, making it visible. (Courtesy of DOE/Lawrence Berkeley National Laboratory)" width="320" class="size-medium wp-image-1824717"/></a>
Instead of turning into a black hole after the explosion, SN 2007bi went through a nuclear runaway, making it visible. (Courtesy of DOE/Lawrence Berkeley National Laboratory)
A super-bright, long-lasting supernova known as SN 2007bi turns out to be the first example of stars that populated the universe, according to new research.

SN 2007bi was found early in 2007 in a nearby dwarf galaxy by the international Nearby Supernova Factory (SNfactory) based at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory.

“It’s significant that the first unambiguous example of a pair-instability supernova was found in a dwarf galaxy,” said astrophysicist Peter Nugent in a press release. “These are incredibly small, very dim galaxies that contain few elements heavier than hydrogen and helium, so they are models of the early Universe.”

The unusual spectrum of the supernova evoked astronomers at the University of California at Berkeley to participate in a collaboration led by Avishay Gal-Yam of Israel’s Weizmann Institute of Science to collect and analyze much more data as the supernova slowly faded away over a year and a half.

The study indicated that the supernova’s precursor star could only have been a giant weighing more than 200 times the mass of our sun and initially containing few elements other than hydrogen and helium—a star similar to our belief of what the very first stars were in the early universe.

“SN 2007bi was the explosion of an exceedingly massive star,” said Alex Filippenko, a professor in the Astronomy Department at UC Berkeley.

“But instead of turning into a black hole like many other heavyweight stars, its core went through a nuclear runaway that blew it to shreds. This type of behavior was predicted several decades ago by theorists, but never convincingly observed until now.”

SN 2007bi is the first confirmed observation of a pair-instability supernova. The researchers describe their results in the Dec. 3 issue of Nature.

“Because the core alone was some 100 solar masses, the long-hypothesized phenomenon called pair instability must have occurred,” said Nugent.

Images of SN 2007bi were taken as part of the Palomar-QUEST Survey, an automated search with the wide-field Oschin Telescope at the California Institute of Technology’s Palomar Observatory. This data was quickly detected and categorized as an unusual supernova by the SNfactory.

After detecting the supernova more than a week after its peak of brightness, the astronomers observed and obtained data during its 555-day fadeaway.

According to Nugent, after looking through Catalina Sky Survey’s record of SN 2007bi previously, he could obtain enough information to calculate the duration of the brightening period—70 days.

“The central part of the huge star had fused to oxygen near the end of its life, and was very hot,” said Filippenko. “Then the most energetic photons of light turned into electron-positron pairs, robbing the core of pressure and causing it to collapse. This led to a nuclear runaway explosion that created a large amount of radioactive nickel, whose decay energized the ejected gas and kept the supernova visible for a long time.”

The Berkeley Lab and UC Berkeley’s contribution to this work was supported by the U.S. Department of Energy’s Office of Science, the National Science Foundation, the Gordon and Betty Moore Foundation, the TABASGO Foundation, Gary and Cynthia Bengier, and the Richard and Rhoda Goldman Fund.