The Reactivation of Main-Belt Comet 324P/La Sagra (P/2010 R2)

TL;DR

This paper reports the first reactivation of main-belt comet 324P/La Sagra, confirming recurrent activity driven by sublimation, with detailed observations of dust emission and activity range.

Contribution

It provides the first evidence of recurrent activity in 324P/La Sagra, establishing it as the fourth main-belt comet with confirmed sublimation-driven activity.

Findings

324P/La Sagra reactivated in 2015 after initial activity in 2010-2011.

Confirmed activity through dust tail observations and brightness analysis.

Largest active range and most distant inbound activation point among main-belt comets.

Abstract

We present observations using the Baade Magellan and Canada-France-Hawaii telescopes showing that main-belt comet 324P/La Sagra, formerly known as P/2010 R2, has become active again for the first time since originally observed to be active in 2010-2011. The object appears point-source-like in March and April 2015 as it approached perihelion (true anomaly of ~300 deg), but was ~1 mag brighter than expected if inactive, suggesting the presence of unresolved dust emission. Activity was confirmed by observations of a cometary dust tail in May and June 2015. We find an apparent net dust production rate of <0.1 kg/s during these observations. 324P is now the fourth main-belt comet confirmed to be recurrently active, a strong indication that its activity is driven by sublimation. It now has the largest confirmed active range of all likely main-belt comets, and also the most distant confirmed inbound activation point at R~2.8 AU. Further observations during the current active period will allow direct comparisons of activity strength with 324P's 2010 activity.