Scientists discover largest known fast-rotating asteroid
Researchers have discovered an asteroid approximately 2.53 kilometers in diameter that completes a rotation in just 4.18 minutes. This makes it the largest known fast-rotating asteroid with a diameter exceeding two kilometers.
Scientists in the United States have identified asteroid 491384, measuring approximately 2.53 kilometers in diameter, with an astonishing rotation period of 4.18 minutes. This discovery establishes it as the largest known fast-rotating asteroid exceeding two kilometers in size. The research, utilizing data from the Vera C. Rubin Observatory, was published on the arXiv preprint server and awaits peer review.
Rapidly rotating large asteroids present intriguing challenges to conventional understanding of their structure. It is generally believed that asteroids larger than 150 meters in diameter rarely have rotation periods shorter than 2.2 hours. Faster rotation implies a need for significant internal cohesion within the asteroid to prevent it from disintegrating due to centrifugal forces. Astroids are often thought to be loosely bound rubble piles, with their shape maintained primarily by self-gravity.
Dmitrii Vavilov, Siegfried Eggl, and Sarah Greenstreet from the University of Washington developed new automated analysis software designed to estimate asteroid rotation periods by analyzing variations in their brightness. The software also identifies potentially erroneous measurements and can provide multiple possible periods if the data is not unambiguous. Applying this method to data from the Vera C. Rubin Observatory, the team identified 66 candidate asteroids rotating faster than the traditional "rotational barrier."
In addition to asteroid 491384, another asteroid, 566130, with a diameter over two kilometers, was found to rotate with a period of approximately five minutes. According to the study, both these asteroids would require substantial internal cohesion to remain intact at such rapid rotation speeds. The findings suggest that some asteroids may possess a more robust internal structure than typically assumed for rubble piles. Further development of the software aims to process even larger astronomical survey datasets and identify observational issues.