Discovery of Super-Slow Rotating Asteroids with ATLAS and ZTF photometry

TL;DR

This paper reports the discovery of a new class of super-slow rotating asteroids with periods exceeding 1000 hours, identified through ATLAS and ZTF surveys, suggesting YORP spin-down as a plausible formation mechanism.

Contribution

It introduces a new class of super-slow rotating asteroids and provides the first large sample of such objects with periods over 1000 hours.

Findings

32 out of 39 reported rotation periods exceed previous records.

7 objects have rotation periods longer than 4000 hours.

Super-slow rotators may constitute at least 0.4% of the main-belt asteroid population.

Abstract

We present here the discovery of a new class of super-slow rotating asteroids (P>1000 hours) in data extracted from the Asteroid Terrestrial-impact Last Alert System (ATLAS) and Zwicky Transient Facility (ZTF) all-sky surveys. Of the 39 rotation periods we report here, 32 have periods longer than any previously reported unambiguous rotation periods currently in the Asteroid Light Curve Database. In our sample, 7 objects have a rotation period > 4000 hours and the longest period we report here is 4812 hours (~200 days). We do not observe any correlation between taxonomy, albedo, or orbital properties with super-slow rotating status. The most plausible mechanism for the creation of these very slow rotators is if their rotations were slowed by YORP spin-down. Super-slow rotating asteroids may be common, with at least 0.4% of the main-belt asteroid population with a size range between 2 and 20 km in diameter rotating with periods longer than 1000 hours.