An illustration of the initial explosion in the death of a massive star.
Credit: NASA/GSFC/Dana Bery
Some dying stars smolder into darkness while others quickly shed their coat of hot gases. But some go out with a bang, propelling their remains through the cosmos at more than 99.9997 percent of the speed of light--the maximum speed limit in the universe.
Using a robotic telescope at the European Space Organization?s La Silla Observatory in Chile, called the Rapid Eye Mount (REM) telescope, astronomers have measured once-theoretical speeds of the explosions known as gamma-ray bursts for the first time.
?This is very exciting,? said Stan Woosley, an University of California astronomer and astrophysicist who was not involved in the research. Woosley said the energy found in the bursts ?strain the models? dictating how fast matter can go.
The findings are detailed in the latest issue of the journal Astronomy & Astrophysics.
The bursts last only seconds to several minutes and their intense energy is at very short wavelengths we can't see, so timing and an automated recording method is critical in order to catch one.
Emilio Molinari, an astronomer with the Brera Astronomical Observatory in Italy and co-author of the study, said the observation was possible thanks to quick, automated observations of major galactic catastrophes.
?We can now study in great detail the very first moments following these cosmic catastrophes,? Molinari said.
In two separate events, on April 18 and June 7 of last year, NASA?s Swift satellite detected a bright gamma-ray burst and automatically notified the small REM telescope. Just 40 seconds after each explosion, the robotic observer swung around and aimed its lens at the event. Although the initial explosions were invisible at first, the intense energy heated up nearby gas which could be seen in near-infrared light by the telescope.
By studying the changing brightness of both bursts, the astronomers measured how fast matter was careening away from the bursts. Astrophysicists use a special system to peg the speed of matter, called the Lorentz factor--the higher the number, the closer to the speed of light.
In the case of both bursts, the Lorentz factor was 400--an unprecedented observation until now.
Stefano Covino, another co-author of the study and astronomer at the Brera Astronomical Observatory, said the speed wasn?t the only impressing figure.
"While single particles ? can be accelerated to still larger velocities, the present cases are the equivalent of about 200 times the mass of the Earth acquiring this incredible speed,? Covino said.
"You certainly wouldn't like to be in the way," said Susanna Vergani, another team member.
Now that the team has made the striking observations, they are trying to find some way to explain them. "The next question is which kind of 'engine' can accelerate matter to such enormous speeds," Covino said.
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