Sun Will Emit Supercharged Light As It Dies That Will Pulverize the Asteroids in the Solar System

Around six billion years from now, our sun will run out of fuel and expand massively, pumping out powerful electromagnetic radiation in the process. Researchers have found now that this supercharged light could pulverize the solar system's asteroids.

Dimitri Veras from the University of Warwick in the U.K. and Daniel Scheeres at the University of Colorado, Boulder, found that the radiation given off by stars like our sun in their death throes can spin asteroids to such high speeds that they break apart into successively smaller fragments.

Around 90 percent of the stars in the universe are "main sequence" stars. When these stellar objects have used up all of their hydrogen fuel they balloon to hundreds of times their normal size during what's known as the "giant branch" phase, which lasts "just" a few million years.

As well as growing in size, stars at this stage also experience a huge increase in their luminosity, as they emit intense electromagnetic radiation. Following this stage, the inflated stars then shed their expanded outer layers, collapsing into a dense remnant known as a white dwarf.

According to a study published in the Monthly Notices of the Royal Astronomical Society, the increasingly intense radiation emitted by main-sequence stars during the "giant branch" phase will be absorbed by asteroids.

As radiation is absorbed by these objects, it moves through them before being emitted from a different point. This causes the asteroids to spin increasingly fast until they break up—what's known as the "YORP" effect.

This process continues—with the asteroids breaking into smaller and smaller pieces—until the objects reach between 1 and 100 meters (around 3 and 330 feet) in diameter. According to the researchers, larger asteroids are loosely held together and thus their internal strength is weak, so they break up more easily. On the other hand, smaller asteroids have more internal strength.

The results of the study indicate that during the sun's giant branch phase, asteroids even further away from the sun than Neptune or Pluto would be pulverized by this effect, other than those that are small and have sufficient internal strength to stay intact.

In our solar system, and indeed other star systems, this process of disintegration could take just a few million years—a relatively short timescale in cosmic terms—and would leave behind a disc of debris around the white dwarf.

Stock photo: Artist's illustration of several asteroids. iStock

"When a typical star reaches the giant branch stage, its luminosity reaches a maximum of between 1,000 and 10,000 times the luminosity of our sun," Veras said in a statement. "Then the star contracts down into an Earth-sized white dwarf very quickly, where its luminosity drops to levels below our sun's. Hence, the YORP effect is very important during the giant branch phase, but almost non-existent after the star has become a white dwarf."

"For one solar-mass giant branch stars—like what our sun will become—even exo-asteroid belt analogs will be effectively destroyed. The YORP effect in these systems is very violent and acts quickly, on the order of a million years. Not only will our own asteroid belt be destroyed, but it will be done quickly and violently. And due solely to the light from our sun."

The say that the latest findings could have significant implications for our understanding of planetary systems.

"We investigated this issue because of its important implications for the fate of planetary systems," Veras told Newsweek. "Understanding how exo-asteroids evolve and break up helps to explain (1) the origin of the debris that are currently observed in dying planetary systems, and (2) potentially why we see so much debris in these systems."

"The main implications [of the study] are that much if not most of the debris that we see around stellar remnants may arise from rotational fission, as opposed to destruction from other mechanisms such as collisions between an asteroid and a planet or an asteroid and a star," he said.

This article was updated to include additional comments from Dimitri Veras.