Superfast Jets From Expoding Stars Could Explain Cosmic Speed Freaks

September 16, 1998

GAMMA-ray bursts may be produced by the debris expelled from a supernova in a hyperfast jet, according to a Princeton astronomer. His theory would also explain why some pulsars fly through space much faster than normal stars.

Gamma-ray bursters, which exist at the edge of the Universe, are the source of the most powerful blasts of energy known. Astronomers can only guess at what makes them pack that kind of punch, but the discovery last year of X-ray and optical "afterglows" associated with these bursts suggests that they might be the fading fireballs of some kind of stellar explosion. Now Renyue Cen of Princeton University in New Jersey is suggesting that these intense bursts of energy might come from a supernova that is expelling material far faster in one direction than in others.

In a paper to appear in Astrophysical Journal Letters Cen speculates that some unknown process sweeps a path free of protons and neutrons, allowing the neutrinos formed within the exploding star to escape. Some of the neutrinos decay into electrons and positrons, forming a jet travelling at about 99á9994 per cent of the speed of light.

The electrons would emit light as they interacted with magnetic fields. Because they are moving so fast, the Doppler effect would boost this radiation to gamma-ray frequencies, producing the burst that we observe.

Cen's theory would also explain why some pulsars are moving at up to 500 kilometres per second-tens of times faster than ordinary stars. "A supernova jet propels a pulsar in the opposite direction just like the exhaust of a rocket," says Cen.

"There is good reason to believe that at least one gamma-ray burster is associated with a supernova and I'm not surprised if high-velocity pulsars are associated with supernovae too," says Andy Fabian of the University of Cambridge.

Proof could come if scientists observed a gamma-ray burst and a supernova going off together. But this will not be easy. "Unfortunately, supernovae are extremely faint and hard to spot at the typical distance of gamma-ray bursters," says Cen.

He also suggests that all supernovae may produce superfast jets, but that we only see them as a gamma-ray burst when the jet points our way. Since several supernovae are known to go off every century in our Galaxy, Cen believes that every few hundred million years the Earth could find itself looking straight down the jet of a nearby gamma-ray burst-with extremely serious consequences.

"The effect on life on Earth would be catastrophic and might well trigger mass extinctions," says Cen.

Author: Marcus Chown



New Scientist

Related Supernova Articles from Brightsurf:

Scientists discover supernova that outshines all others
A supernova at least twice as bright and energetic, and likely much more massive than any yet recorded has been identified by an international team of astronomers, led by the University of Birmingham.

Supernova observation first of its kind using NASA satellite
Their research, detailed in the Monthly Notices of the Royal Astronomical Society, represents the first published findings about a supernova observed using TESS, and add new insights to long-held theories about the elements left behind after a white dwarf star explodes into a supernova.

Astronomers find possible elusive star behind supernova
Astronomers may have finally found a doomed star that seemed to have avoided detection before its explosive death.

Stellar thief is the surviving companion to a supernova
Hubble found the most compelling evidence that some supernovas originate in double-star systems.

Supernova may have 'burped' before exploding
Only by increasing the rate at which telescopes monitor the sky has it been possible to catch more Fast-Evolving Luminous Transients (FELTs) and begin to understand them.

An unusual white dwarf may be a supernova leftover
Astronomers have identified a white dwarf star in our galaxy that may be the leftover remains of a recently discovered type of supernova.

Researchers show how to make your own supernova
Researchers from the University of Oxford are using the largest, most intense lasers on the planet, to for the first time, show the general public how to recreate the effects of supernovae, in a laboratory.

The big star that couldn't become a supernova
For the first time in history, astronomers have been able to watch as a dying star was reborn as a black hole.

Seeing quadruple: Four images of the same supernova, a rare find
Galaxies bend light through an effect called gravitational lensing that helps astronomers peer deeper into the cosmos.

Explosive material: The making of a supernova
Pre-supernova stars may show signs of instability for months before the big explosion

Read More: Supernova News and Supernova Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to