# Confirmation of Large Super-Fast Rotator (144977) 2005 EC127

## TL;DR

This paper confirms that asteroid 2005 EC127 is a large super-fast rotator with a rotation period of 1.65 hours, challenging the typical rubble-pile structure assumption for its size and suggesting internal cohesion or high density.

## Contribution

First confirmation of a large super-fast rotator among inner-main-belt asteroids, providing insights into its internal structure and cohesion properties.

## Key findings

- 2005 EC127 completes a rotation in 1.65 hours
- It likely has internal cohesion or high bulk density
- Only six large super-fast rotators are known to date

## Abstract

(144977) 2005 EC127 is an V-/A-type inner-main-belt asteroid with a diameter of 0.6 +- 0.1 km. Asteroids of this size are believed to have rubble-pile structure, and, therefore, cannot have a rotation period shorter than 2.2 hours. However, our measurements show that asteroid 2005 EC127 completes one rotation in 1.65 +- 0.01 hours with a peak-to-peak light-curve variation of ~0.5 mag. Therefore, this asteroid is identified as a large super-fast rotator. Either a rubble-pile asteroid with a bulk density of ~6 g cm^-3 or an asteroid with an internal cohesion of 47 +- 30 Pa can explain 2005 EC127. However, the scenario of high bulk density is very unlikely for asteroids. To date, only six large super-fast rotators, including 2005 EC127, have been reported, and this number is very small when compared with the much more numerous fast rotators. We also note that none of the six reported large SFRs are classified as C-type asteroids.