The threat of centaurs for the earth

Astrophysicists Mattia Galiazzo and Rudolf Dvorak of the University of Vienna, in collaboration with Elizabeth A. Silber (Brown University, USA), studied the long-term development of the Centaurs (minor bodies of the solar system initially orbits between Jupiter and Neptune).

These researchers estimated the number of close encounters and impacts with terrestrial planets after the so-called heavy bombardment late (about 3.8 billion years ago), as well as the possible size of the craters may occur after a collision with the Earth (and other terrestrial planets). The publication was recently published in the Monthly Notices of the Royal Astronomical Society.

Centaurs are the objects of the solar system whose orbits lie between those of the giant planets. They come mainly from Transneptunian objects and are part of the sources of objects close to the Earth. It is therefore crucial to understand their orbital evolution which, in some cases, could lead to a collision with terrestrial planets and produce catastrophic events.

The researchers studied the orbital evolution of the Centaurs to the internal solar system and estimated the number of close encounters and impacts with terrestrial planets after the late heavy bombardment (there are about 3.8 billion Years), assuming a stable population Centaurs. "We also estimate the possible crater sizes.

Centaurs can also become active comets, because of the presence of water on many of them. So we also calculate the approximate amount of water released to the Earth, which is comparable to the amount of water present in the Adriatic Sea, now. We also found sub-regions of the Centaurs where the potential impactors come from, "explains Mattia Galiazzo.

Although the size of the craters can reach several hundred kilometers in diameter given the known population of Centaurs, the majority of craters would have an area less than 10 km. For all planets and an average impactor size of about 12 km in diameter, we have on average 2 impacts since late heavy bombardment for the Earth and between 1 and 2 for Venus. Fortunately, this "bombing" is less intense (by at least a tenth) of the impacts caused by the asteroids between Mars and Jupiter.

However, Centaurs arrive on average much faster and have larger bodies in general. For smaller Centaurs (for example, with a diameter D> 1 km), the frequency of impact is much greater, about one every 14 Myr for the Earth, 13 Myr for Venus and 46 for Mars in the recent solar system.

The researchers discovered that about half of Centaurs can enter the region of the Earth's planet and about 7% of them can interact with terrestrial planets. In the event of an impact, the Centaurs could be at the origin of disasters, such as the extinction of events as we know it today.

These results make an important contribution to the analysis of catastrophic events of extraterrestrial origin, which could occur not only on our planet, but also on planets such as Mars and Venus.

"Our work also provides the framework to better understand past events and their impact on life on Earth and other terrestrial planets," says Galiazzo. For example, Dvorak said: "Such events could have a direct impact on life by destroying it (for example, the Earth) or by creating favorable conditions (for example, hydrotermic activity) for the new In addition, our results provide more answers to the evolution of the current solar system. "

Another interesting fact, Silber says: "Centaurs can bring water to Mars after a collision" and recent missions confirm the presence of water on Mars.

Research Report: The threat of centaurs to terrestrial planets and their orbital evolution as impactors.

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