Photometric and dynamic characterisation of active asteroid (248370) 2005 QN173

TL;DR

This study characterizes the physical and dynamical properties of active asteroid (248370) 2005 QN173, revealing rotation periods, activity fading, and its likely origin in the Themis family, suggesting rotation and sublimation as activity drivers.

Contribution

First detailed physical and dynamical analysis of (248370) 2005 QN173, linking its activity to rotation and sublimation, and associating it with the Themis asteroid family.

Findings

Rotation periods of 2.7 and 4.1 hours suggest rotation-induced activity.

Activity level is fading slowly at 0.006 mag/day, compatible with sublimation.

Likely origin in the Themis family and the young 288P cluster.

Abstract

We present the physical and dynamical properties of the recently discovered active asteroid (248370) 2005 QN173 (aka 433P). From our observations, we derived two possible rotation period solutions of 2.7 and 4.1 hours. The corresponding light curve amplitudes computed after correcting for the effect of coma are 0.28 and 0.58 mag, respectively. Both period solutions are shorter than the critical rotation limit computed for a strengthless triaxial ellipsoid, suggesting that rotation mass shedding should at least partly be responsible for the observed activity. We confirm that the activity level is fading further, but at a very modest rate of only 0.006 mag/day, still also compatible with sublimation-driven activity. We found that 248370 likely belongs to the Themis asteroid family, making it a fourth main-belt comet associated with this group. Orbital characteristics of 248370 are also consistent with its origin in the young 288P cluster of asteroids. The 288P cluster is associated with its namesake main-belt comet, providing an exciting possibility for a comparative analysis of intriguing main-belt comets 248370 and 288P.