Spin vectors in the Koronis family: V. Resolving the ambiguous rotation period of (3032) Evans

TL;DR

This paper resolves the ambiguous rotation period of asteroid (3032) Evans using a sidereal counting approach, confirming its spin rate is consistent with a reaccumulated rubble-pile object and aligning with YORP spin-up effects.

Contribution

It introduces a sidereal rotation counting method to clarify the rotation period of (3032) Evans, resolving previous ambiguities and providing a full spin vector solution.

Findings

Evans's spin rate is below the rubble-pile spin barrier.

The spin vector is similar to other low-obliquity Koronis family members.

The asteroid's rotation is consistent with YORP spin-up effects.

Abstract

A sidereal rotation counting approach is demonstrated by resolving an ambiguity in the synodic rotation period of Koronis family member (3032) Evans, whose rotation lightcurves' features did not easily distinguish between doubly- and quadruply-periodic. It confirms that Evans's spin rate does not exceed the rubble-pile spin barrier and thus presents no inconsistency with being a ~14-km reaccumulated object. The full spin vector solution for Evans is comparable to those for the known prograde low-obliquity comparably-fast rotators in the Koronis family, consistent with having been spun up by YORP thermal radiation torques.