Supernovas struck Earth between 3 million and 7 million years ago

a Recent study It studies how the Earth is exposed to explosions from supernovae (plural of Supernova (SN)) that occurred 3 million years ago (mya) and 7 mya in order to ascertain the distances in which these explosions originated. Using the living (non-decayed) radioactive isotope 60-Fe, which is produced from supernovae, a team of researchers at the University of Illinois were able to determine the approximate astronomical distances of the explosions, which they referred to as the Pliocene Supernova (SN Plio). , 3 mya) and the Miocene supernova (SN myo, 7 mya).

“Supernovae are dramatic examples of the fact that stars have life cycles.” Dr. Brian Fields“It’s a lot of fun,” he says, who is a professor of astronomy at the University of Illinois and a co-author of the study The universe today. “Supernova explosions represent the spectacular death of the most massive stars, those with masses at least eight times that of the Sun. They play a central role in astrophysics and cosmology for many reasons.

For the study, the researchers conducted laboratory analyzes of the species of living (non-decayed) radioactive iron isotopes of 60-Fe based on several previous studies in which 60-Fe samples were obtained from the Earth’s crust, deep-sea sediments, and lunar regolith. . While the ages of these samples were obtained using the 60-Fe half-life of 2.62 million years and determined that they originated from two supernova explosions, the goal of this latest study is to determine the distances to the two explosions.

The study results suggest that SN Plio originated between 20 to 140 parsecs, or 65 to 457 light-years (nighttime), from Earth, but a more likely range is between 50 to 65 parsecs, or 163 to 212 light-years away. For SN Mio, the team determined the approximate distance is 110 computers, or 359 years. For context, 1 pc is equivalent to 3.26 ly. While these may be considered relatively “safe” distances from Earth, how might such explosions affect the evolution of our solar system?

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“If a supernova explodes near Earth or another Earth-like planet, the consequences could be life-destroying,” Dr. Fields says. The universe today. “The supernova explosion creates high-energy radiation – gamma rays – that will irradiate the Earth’s atmosphere for months after the explosion. Our atmosphere will protect us from direct exposure to these gamma rays, but at a great cost: the ozone layer in the upper atmosphere will decrease dramatically. This will make the Earth vulnerable to harsh ultraviolet rays from the Sun, which can be harmful to many life forms on Earth.It will take the Earth several years to regenerate ozone.

Supernovas are among the most amazing sights ever observed in the universe. Oldest supernova recordednow named RCW 86 or SN185It happened on December 7, 185 AD, and was documented by Chinese astronomers. They referred to this event as the “guest star” and noted that its light remained in the sky until June 186 AD before disappearing. Nowadays astronomers refer to this event as a transient astronomical event and suggest that RCW 86, located about 2,800 parsecs (9,100 light-years (ly)) from Earth with an estimated diameter of 85 light-years, was likely a star. Type Ia supernova.

Dr. Fields says universe today, “Supernova explosions are rare. Every century, there are about one to three such events in our entire Milky Way Galaxy. So, most of them explode far away, causing no harm to Earthlings. But over time periods of several million years, It is very likely that one of them will explode near the ground, even if it is very close.

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Dr. Fields points out that the mass extinction that occurred at the end of the Devonian period about 360 million years ago was the result of one or more supernovae, he says. The universe today There are currently no “supernova candidates that pose a threat”, as in “there are no supernovae so close to us that we are in their kill zones”. .

One of the most famous supernovas (in the future) is a star Betelgeusewhich is A Red giant It is located approximately 550 years from Earth and is the second brightest star in the Orion constellation. Betelgeuse made headlines in late 2019 when astronomers noticed the star was dimming Some suggestions It was about to go supernova. However, follow-up observations in August 2020 indicated that the dimming was due to A smother It formed from extremely hot material expelled by the massive star, which was later confirmed in August 2022. Stady. While Betelgeuse is known to vary in brightness due to changes in its temperature and size, some may wonder when it will explode?

“It’s not known when,” Dr. Fields tells Universe Today [Betelgeuse] It will explode, because as far as we know, the late stages of a massive star’s life do not cause noticeable changes in the star’s surface region. Thus, Betelgeuse could be the next supernova in our galaxy, but it could also explode 100,000 years from now. But his eventual death is certain, so enjoy him in Orion now while you still can!

What new discoveries will astronomers make about supernovas in the coming years and decades? Only time will tell, that’s why we’re studying!

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As always, keep doing science and keep researching!

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