Gamma-ray burst illustration. (c) NASA
Most of us tend to believe the Earth is a safe heaven, with little regard to outerwordly consequences. The truth is our planet, although without a doubt a true gem within our galaxy, is susceptible to a slew of events triggered from within or well beyond our solar system. A lot of them are very dangerous to life on Earth, be it a menacing asteroid, a solar flare or even a terrifying gamma-ray burst.
Researchers of Washburn University, in Topeka, Kan. have studied gamma-ray bursts and its potential consequences, and now claim the Earth quite probably has been met by such events during its history, with dramatic consequences on the life harbored within it.
Gamma-ray bursts typically occur when two stars collide, a process which leads to a giant energy burst into outer space. The gamma-ray bursts have the capability of depleting stratospheric ozone, allowing the most powerful and damaging forms of ultraviolet radiation to reach the Earth’s surface. Researchers are now beginning to connect the timing of these gamma-ray bursts to extinctions on Earth that can be dated through the fossil record.
“We find that a kind of gamma-ray burst — a short gamma-ray burst — is probably more significant than a longer gamma-ray burst,” study researcher Brian Thomas of Washburn University, in Topeka, Kan., said in a statement. “The duration is not as important as the amount of radiation.”
There are two types of gamma-ray bursts: a longer, brighter burst caused by two collinding stars, as discussed earlier, and a short timed burst. The later caused by the collision of two black holes or neutron stars are even more harmful bursting an outrageous amount of radiation, even though the event only lasts a second.
Such an event, the researchers say, happens about once per 100 million years in any given galaxy. But if one did happen here, the results would be devastating. According to the scientists treating the study, if such an event should occur inside the Milky Way, dire consequences might afflict the Earth. The radiation, after reaching the atmosphere, would caused the depletion of the ozone by knocking free oxygen and nitrogen atoms so they can recombine into ozone-destroying nitrous oxides. Earth would have been hit by several of these short-hard events over the course of its 4.5-billion-year history, according to the study authors.
The researchers are now looking of evidence of such an event. If a gamma-ray burst would have hit the Earth, the best sign of this would be the discovery of isotope iron-60. Isotopes like these can reveal the strata of the events, it then becomes a matter of looking for extinction events that correlate and examining which species died and which survived.
“I work with some paleontologists and we try to look for correlations with extinctions, but they are skeptical,” said Thomas. “So if you go and give a talk to paleontologists, they are not quite into it. But to astrophysicists, it seems pretty plausible.”
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