Exploding stars some 65 light-years away may have caused mass extinction on Earth: Study

Curious minds have always wondered about way extinction of species might have happened on Earth. most popular hyposis put forth in most well-kwn extinction — disaurs — les to an asteroid impact. But end for Earthly creatures can happen by factors that are distant of light-years away.

A group of researchers has said that killer cosmic rays from nearby supervae could be culprit behind at least one mass extinction event and finding certain rioactive isotopes in Earth’s rock record could confirm this scenario. A superva is explosion of a star and is largest such cosmic phemena that takes place in .

A new study led by University of Illiis, Urbana-Champaign astromy and physics professor Brian Fields explores possibility of astromical events being responsible for an extinction event that occurred 359 million years ago, at boundary between Devonian and Carboniferous periods. 

Superva-extinction connection

team concentrated on Devonian-Carboniferous boundary because those rocks contain hundreds of thousands of generations of plant spores that appear to be sunburnt by ultraviolet light – evidence of a long-lasting ozone-depletion event.

According to Fields, Earth-based catastrophes such as large-scale volcanism and global warming can destroy ozone layer, too, but evidence for those is inconclusive for time interval in question. Inste, he says, researchers propose that one or more superva explosions, about 65 light-years away from Earth, could have been responsible for protracted loss of ozone.

“To put this into perspective, one of closest superva threats today is from star Betelgeuse, which is over 600 light-years away and well outside of kill distance of 25 light-years,” said gruate student and study co-author rienne Ertel.

team explored or astrophysical causes for ozone depletion, such as meteorite impacts, solar eruptions, and gamma-ray bursts. But se events end quickly and are unlikely to cause long-lasting ozone depletion that happened at end of Devonian period, said ar  study co-author Jesse Miller.

A superva, on or hand, delivers a one-two punch, researchers explained. explosion immediately bas Earth with damaging UV, X-rays, and gamma rays. Later, blast of superva debris slams into solar system, subjecting planet to long-lived irriation from cosmic rays accelerated by superva. dam to Earth and its ozone layer can last for up to 1,00,000 years.

However, fossil evidence indicates a 3,00,000-year decline in biodiversity leing up to Devonian-Carboniferous mass extinction, suggesting possibility of multiple catastrophes, maybe even multiple supervae explosions.

“This is entirely possible,” Miller said. “Massive stars usually occur in clusters with or massive stars, and or supervae are likely to occur soon after first explosion.”

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Rioactive elements and life

team said key to proving that a superva occurred would be to find rioactive isotopes plutonium-244 and samarium-146 in rocks and fossils deposited at time of extinction. "Neir of se isotopes occurs naturally on Earth today, and only way y can get here is via cosmic explosions,” said co-author Zhenghai Liu.

According to Fields.  rioactive species born in superva are like green bananas and like m, Pu-244 and Sm-146 decay over time. "So if we find se rioisotopes on Earth today, we kw y are fresh and t from here – green bananas of isotope world – and thus smoking guns of a nearby superva.”

Researchers have yet to search for Pu-244 or Sm-146 in rocks from Devonian-Carboniferous boundary. Fields’ team said its study aims to define patterns of evidence in geological record that would point to superva explosions.

“ overarching mess of our study is that life on Earth does t exist in isolation,” Fields said. “We are citizens of a larger cosmos, and cosmos intervenes in our lives – often imperceptibly, but sometimes ferociously.”

(Im credit: Twiter/@uofigrainger)

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