Discovery of Main-Belt Comet P/2006 VW139 by Pan-STARRS1

TL;DR

This paper reports the discovery and detailed analysis of main-belt comet P/2006 VW139, providing evidence of sublimation-driven activity, its physical properties, and its potential association with the Themis asteroid family.

Contribution

It presents the first detailed observational and dynamical study of P/2006 VW139, confirming its cometary nature and linking it to the Themis family, a novel insight into main-belt comets.

Findings

P/2006 VW139 exhibits a dust tail and trail similar to other main-belt comets.

Photometry indicates sustained cometary activity over 30 days.

Dynamical analysis suggests a stable orbit and possible family association.

Abstract

Main belt asteroid (300163) 2006 VW139 (later designated P/2006 VW139) was discovered to exhibit comet-like activity by the Pan-STARRS1 survey telescope using automated point-spread-function analyses performed by PS1's Moving Object Processing System. Deep follow-up observations show both a short (\sim 10") antisolar dust tail and a longer (\sim 60") dust trail aligned with the object's orbit plane, similar to the morphology observed for another main-belt comet, P/2010 R2 (La Sagra), and other well-established comets, implying the action of a long-lived, sublimation-driven emission event. Photometry showing the brightness of the near-nucleus coma remaining constant over \sim 30 days provides further evidence for this object's cometary nature, suggesting it is in fact a main-belt comet, and not a disrupted asteroid. A spectroscopic search for CN emission was unsuccessful, though we find an upper limit CN production rate of Q_CN < 1.3x10^24 mol/s, from which we infer a water production rate of Q_H2O < 10^26 mol/s. We also find an approximately linear optical spectral slope of 7.2%/1000A, similar to other cometary dust comae. Numerical simulations indicate that P/2006 VW139 is dynamically stable for > 100 Myr, while a search for a potential asteroid family around the object reveals a cluster of 24 asteroids within a cutoff distance of 68 m/s. At 70 m/s, this cluster merges with the Themis family, suggesting that it could be similar to the Beagle family to which another main-belt comet, 133P/Elst-Pizarro, belongs.