Astronomers have long been puzzled by the unusual shapes of the tiny asteroids Dimorphos and Selam, but a recent study sheds light on why they look so strange. These “moonlet” asteroids are part of binary asteroid systems, similar to mini Earth-moon systems, and are more common than previously thought.
Most moonlet asteroids typically have a prolate shape, resembling upright footballs as they orbit their parent asteroids. However, Dimorphos and Selam stand out with their oblate and bilobate shapes, respectively. The study conducted by researchers from European and American universities used computer models to simulate the formation of these odd-shaped asteroids.
The study found that the final shape of a moonlet asteroid is determined by the gravitational force of the parent asteroid and the nature of collisions within the debris disk surrounding it. Factors such as the density of the parent asteroid and the distance of the moonlet from the parent play a crucial role in shaping the asteroid. Moonlets that form beyond the Roche limit of the parent asteroid tend to acquire oblate shapes, while those within the limit maintain prolate shapes.
Collisions between precursor moonlets also influence the final shape, with side-to-side collisions resulting in oblate shapes and edge-to-edge collisions creating bilobate objects. The researchers believe that the odd shapes of Dimorphos and Selam may be more common in the asteroid population than previously estimated, as current technology is biased against detecting oblate asteroids.
Overall, the study provides valuable insights into the formation of these unusual asteroids and highlights the complex processes that shape our cosmic neighborhood. With further research and advancements in asteroid detection technology, more strange and fascinating discoveries in space are waiting to be uncovered.
