Two giant asteroids finish a spin in five minutes

Dmitrii Vavilov, Siegfried Eggl, and Sarah Greenstreet developed a rotation-period method that varies the order of its Fourier model for each asteroid and returns alternative periods with probabilities when the sparse survey sampling leaves more than one solution. They applied it to Solar System objects in the Vera C. Rubin Observatory's Data Preview 2 catalog.

The analysis identifies 66 objects rotating faster than the classical 2.2-hour rubble-pile barrier. Asteroids 491384 and 566130 are each larger than two kilometers yet complete a turn in roughly five minutes; at about 2.5 kilometers, 491384 becomes the largest known ultra-fast rotator in the sample. Surviving that pace implies substantial internal cohesion, though the preprint still awaits peer review.

Why it matters

Extreme rotation tests whether an asteroid is a loose aggregate or a stronger body. Rubin's scale also shows how survey pipelines can surface rare natural outliers without treating each odd light curve as exotic technology.

What the source establishes

Fresh preprint submitted October 6. The periods come from survey photometry and a new automated reliability model; independent light curves would provide the strongest confirmation for the most extreme objects.