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Rubin Observatory Study Finds Record-Fast Main-Belt Asteroid Spinning Every 113 Seconds

A first peer-reviewed analysis of Rubin data points to rock-solid interiors for several main-belt asteroids.

Overview

  • The Astrophysical Journal Letters paper analyzed nine nights of April–May 2025 Rubin observations, marking the first peer-reviewed use of the LSST camera.
  • Asteroid 2025 MN45, about 710 meters across in the main belt, completes a rotation in roughly 113 seconds.
  • Of roughly 75 measured objects, 19 exceed the main-belt spin barrier, including 16 with periods between about 13 minutes and 2.2 hours and three under five minutes.
  • Modeling indicates these fast rotators require substantial cohesion, with estimates near 900 kPa for MK41 and around 9,000 kPa for MN45.
  • Researchers say the unexpected prevalence of rapid spinners suggests collision-only models are incomplete, and expanded Rubin surveys in 2026 are expected to test these ideas.