On the rotation of M-type asteroids: Statistical evidence for higher rotation ratesOPEN ACCESS
Fernando Abarzuza, Noemí Pinilla-Alonso, Miquel Serra-Ricart, Santiago Iglesias Álvarez, Miguel R. Alarcon
Icarus, In Press, Journal Pre-proof, Available online 27 May 2026
“Highlights
- Largest dataset to date of M-type asteroid rotation rates assembled using Mahlke taxonomy.
- M-type asteroids rotate faster than non-M-type asteroids of comparable size.
Results are robust across classification thresholds, Monte Carlo approaches, jackknife tests, and family membership checks. - Rotational excess is consistent with higher internal cohesion and strength in M-type asteroids.”
“Rotational dynamics of asteroids carry important information about their internal structure, collisional history and material composition. This work investigates whether M-type asteroids exhibit systematically higher rotation rates than the broader asteroid population. Using Mahlke’s probabilistic taxonomy combined with rotation periods and diameters from the Small-Body Database, we analyse the rotational properties of candidate M-type asteroids and compare them with the general asteroid population. Because asteroid rotation strongly depends on size, the comparison is performed using a Monte Carlo resampling approach conditioned on the diameter distribution of the M-type sample. The results indicate that the M-type asteroids rotate, on average, faster than other asteroids of comparable size. While limitations remain due to sample size, heterogeneous data sources, and possible selection effects, the analysis provides statistical evidence that M-type asteroids are associated with higher rotation rates. This finding is consistent with an association between M-type classification and enhanced rotational properties, with potential implications for the internal structure and collisional evolution of small bodies in the Solar System.”
