Astronomers have discovered a near-Earth asteroid that is torn apart by centrifugal forces

The asteroid Didim, whose satellite Dimorph was “attacked” by the American device DART six months ago, scatters stones and dust around it. This is because the Sun has been spinning it at high speeds and rocks at its equator can break away from the surface, according to the study. Finished in the archive of electronic preprints.

In September 2022, NASA’s DART spacecraft made a planned impact with asteroid Dimorph, a satellite of the larger asteroid Didymus, an experiment the world was watching at that time. The goal was to test the possibility of changing the trajectory of potentially dangerous asteroids in the future using kinetic impact. Recently, scientists from the University of Maryland reported that the result of the bombardment exceeded expectations – it was assumed that Dimorph’s 12-hour orbital period around Didyma should have been reduced by 10 minutes, but measurements showed that it had been reduced by half an hour. hour.

However, a new study by scientists from Spain and Argentina has shed new light on the asteroid Didim, the heaviest body in this pair. Observations have shown that this asteroid rotates around its axis very quickly, completing a full revolution in 2 hours and 16 minutes. Scientists know that asteroids can rotate strongly due to the so-called YORP effect, which occurs due to the fact that the Sun heats different parts of the surface differently and the emission of thermal photons creates an asymmetric effect, either in rotating, or by slowing down the asteroid. . The force created by photons is extremely weak, however, acting over millions of years, it can spin asteroids at impressive speeds.

Knowing the mass, density and shape of the asteroid Didim, scientists found that the body, due to the rotation, is “on the verge of stabilization” due to centrifugal forces acting on particles and stones individuals on its surface. Modeling showed that near the asteroid’s equator, in the latitude range (+28◦, −19◦), where centrifugal forces are maximum, stones and dust can spontaneously detach from the surface, fly through space or fall back.

“Most of the particles (more than 97%) fall, their flight time depends on the size, but is generally less than 5 hours,” write the authors. “Heavy particles can fly for a while, fall to the surface, break off again and again, or fall at latitudes where their separation is no longer possible.”

According to the scientists, the lighter particles fall faster when they are brought to the surface by the pressure of the solar wind on the dayside. Heavier particles can rise to high orbits, fall to the surface of a Dimorph satellite, or even leave the binary system.

Scientists hope to confirm the calculations after receiving results from the European Hera mission, which will arrive at the two asteroid system in 2027 to study the results of the bombardment.