# Searching for Super-Fast Rotators Using the Pan-STARRS 1

## TL;DR

This study used Pan-STARRS 1 data to identify seven new large super-fast rotators among asteroids, expanding understanding of their distribution and properties, and suggesting a lower prevalence in the inner main belt.

## Contribution

First large-scale survey of asteroid rotation periods with Pan-STARRS 1, discovering seven new large super-fast rotators and analyzing their distribution and characteristics.

## Key findings

- Seven new large SFRs discovered, increasing known population.
- Large SFRs are diverse in color and location, mainly in the mid main belt.
- Spin-rate distribution shows a drop at >5 rev/day for outer main-belt asteroids.

## Abstract

A class of asteroids, called large super-fast rotators (large SFRs), have rotation periods shorter than 2 hours and diameters larger than ~ 0.3 km. They pose challenges to the usual interior rubble-pile structure unless a relatively high bulk density is assumed. So far, only six large SFRs have been found. Therefore, we present a survey of asteroid rotation period using Pan-STARRS 1 telescopes during 2016 October 26 to 31 to search more large SFRs and study their properties. A total of 876 reliable rotation periods are measured, among which seven are large SFRs, thereby increasing the inventory of known large SFRs. These seven newly discovered large SFRs have diverse colors and locations in the main asteroid belt, suggesting that the taxonomic tendency and the location preference in the inner main belt of the six perviously known large SFRs could be a bias due to various observational limits. Interestingly, five out of the seven newly discovered large SFRs are mid main-belt asteroids. Considering the rare discovery rates of large SFR in the previously similar surveys (Chang et al., 2015, 2016) and the survey condition in this work, the chance of detecting a large SFR in the inner main belt seems to be relatively low. This probably suggests that the inner main belt harbors less large SFRs than the mid main belt. From our survey, we also found the drop in number appearing at f > 5 rev/day on the spin-rate distribution for the outer main-belt asteroids of D < 3 km, which was reported for the inner and mid main belt by (Chang et al., 2015, 2016).