(NLDO) - 372 and 445 million years ago, two giant cosmic monsters, with a mesmerizing blue color, almost wiped out all life on Earth.
During the Cambrian period (about 541-485 million years ago), the first period of the Paleozoic era, life on Earth underwent a spectacular biological explosion, laying the foundation for the diverse world we see today.
But two mysterious disasters occurred later, during the Ordovician period (about 485-445 million years ago) and the Devonian period (about 416-359 million years ago).
An illustration of Zeta Puppis, an O-type star 1,400 light years from Earth, similar to the one that caused a mass extinction in the past - Photo: Tahina Ramiaramanantsoa.
At the end of the Ordovician period (445 million years ago), an extinction event killed 60% of marine invertebrates.
It was a huge disaster because at that time, most life on Earth was still confined within the oceans.
Near the end of the Devonian period (372 million years ago), another major extinction event killed 70% of living species and led to major changes in the fish that survived in lakes and oceans.
New research from Keele University (UK) and the University of Alicante (Spain) indicates that the death of blue giant stars may be the cause of these two great disasters.
Of course they did not collide directly with Earth like the dinosaur-killing Chicxulub asteroid.
But when these giant monsters explode, they release such a powerful source of energy that even from a great distance, the extreme cosmic rays from them are enough to devastatingly change the living environment as well as directly impact living things.
Astronomers came to this conclusion after investigating massive O- and B-type stars within 3,260 light-years of the Sun.
These are the largest, most extreme types of stars. O-type stars are hotter than 30,000 K, while B-type stars are around 10,000-30,000 K, giving them blue and blue-white hues, respectively.
For comparison, our Sun is a yellow G-type star, with a temperature of about 5,500 K.
Each K on the Kelvin scale (1 K) is equal to 1 degree C on the Celsius scale we use, with a difference of 273.15 degrees (0 degrees C is 273 K).
Studying the distribution of O- and B-type stellar monsters helps scientists understand more about how star clusters and galaxies form, as well as calculate the rate at which supernovae (star explosions) occur in our own Milky Way galaxy.
In the process, the team calculated the supernova rate within 65 light years of the Sun and compared it with data from past mass extinction events.
The results published in the scientific journal Monthly Notices of the Royal Astronomical Society show that two supernovae of type O and B can explain two out of five mass extinctions that the planet has experienced, the two events mentioned above.
For now, there's some good news: There are only two relatively nearby stars that could go supernova in the next million years or so: Antares and Betelgeuse.
However, both are more than 500 light years away from us, so their impact on future terrestrial life is certainly much lower.
Source: https://nld.com.vn/70-su-song-trai-dat-tung-bi-tieu-diet-boi-quai-vat-xanh-1962503180941418.htm
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