Asteroid belt will be pulverized by the sun in six billion years, researchers predict


According to new research by scientists at the University of Warwick and the University of Colorado, scientists at Boulder, electromagnetic radiation from stars at the end of their giant branch phase – lasting only a few million years. before they collapsed into white dwarfs – would be strong enough to spin even at a distance from asteroids at high speed until they split; as a result, even the asteroid belt of the solar system will be easily pulverized by the Sun in billions of years.

Artist’s impression of an asteroid belt around the bright star Vega. Image credit: NASA / JPL-Caltech.

Once main sequence stars like our Sun have burned off all of their hydrogen fuel, they then grow hundreds of times larger during a giant branch phase and increase their brightness 10,000 times, emitting intense electromagnetic radiation. .

When this expansion stops, a star loses its outer layers, leaving behind a dense core known as a white dwarf.

The star’s radiation will be absorbed by orbiting asteroids, redistributed internally and then emitted from another location, creating an imbalance.

This imbalance creates a torque effect that causes the asteroid to spin very gradually, eventually reaching breaking speed at one full rotation every two hours. This effect is known as the YORP effect, named after four scientists (Yarkovsky, O’Keefe, Radzievskii, Paddack) who contributed ideas for the concept.

Eventually, this pair will split the asteroid into smaller pieces.

The process will then repeat itself in several stages and the asteroids will decompose into smaller and smaller objects after each destruction event.

In most cases, there will be more than ten fission events – or ruptures – before the pieces get too small to be affected.

“When a typical star reaches the giant branch stage, its luminosity peaks between 1,000 and 10,000 times the luminosity of our Sun,” said lead author Dr Dimitri Veras, researcher at the University of Warwick .

“Then the star contracts very quickly into an Earth-sized white dwarf, where its luminosity drops to levels below that of our Sun.”

“Therefore, the YORP effect is very strong during the giant branch phase, but almost non-existent after the star becomes a white dwarf.”

“For a branch of giant solar-mass stars – like what will become of our Sun – even the analogues of the exo-asteroid belt will indeed be destroyed.”

“The YORP effect in these systems is very violent and acting quickly, on the order of a million years.”

“Not only will our own asteroid belt be destroyed, but it will happen quickly and violently. And only thanks to the light of our Sun.

“The remnants of these asteroids will eventually form a disc of debris around the white dwarf, and the disc will be drawn into the star, ‘polluting’ it.”

“This pollution can be detected from Earth by astronomers and analyzed to determine its composition. “

The study was published in the Monthly notices from the Royal Astronomical Society.


Dimitri Veras & Daniel J. Scheeres. 2020. Post-main sequence debris of the YORP disruption induced by the rotation of small bodies – II. Multiple fissions, internal forces and binary production. MNRAS 492 (2): 2437-2445; doi: 10.1093 / mnras / stz3565

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