Disintegration of active asteroid P/2016 G1 (PANSTARRS)

¹ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
e-mail: ohainaut@eso.org
² Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
³ University of NM – 1700 Lomas Blvd, NE. Suite 2200, Albuquerque, NM 87131-0001 USA
⁴ ESA SSA-NEO Coordination Centre, Largo Galileo Galilei, 1 00044 Frascati (RM), Italy
⁵ INAF – Osservatorio Astronomico di Roma, Via Frascati, 33, 00040 Monte Porzio Catone (RM), Italy
⁶ Indian Institute of Astrophysics, II Block, Koramangala, Bengaluru 560 034, India

Received: 10 May 2019
Accepted: 26 June 2019

Abstract

We report on the catastrophic disintegration of P/2016 G1 (PANSTARRS), an active asteroid, in April 2016. Deep images over three months show that the object is made up of a central concentration of fragments surrounded by an elongated coma, and presents previously unreported sharp arc-like and narrow linear features. The morphology and evolution of these characteristics independently point toward a brief event on 2016 March 6. The arc and the linear feature can be reproduced by large particles on a ring, moving at ~2.5 m s⁻¹. The expansion of the ring defines a cone with a ~40° half-opening. We propose that the P/2016 G1 was hit by a small object which caused its (partial or total) disruption, and that the ring corresponds to large fragments ejected during the final stages of the crater formation.