Comet 73P/Schwassmann-Wachmann 3's Dust Trail as a Source of Pickup Ions

TL;DR

This study investigates how the dust trail of comet 73P/Schwassmann-Wachmann 3 serves as a significant source of pickup ions, using spacecraft data and solar wind measurements to analyze the comet's ion environment.

Contribution

It demonstrates that the extended dust trail of 73P/Schwassmann-Wachmann 3 is a major source of pickup ions, expanding understanding of cometary ion sources beyond the nucleus and immediate tail.

Findings

Pickup ions detected near the comet's dust trail

Alignment of fragments with spacecraft was poor for direct tail transport

The dust trail significantly contributes to the comet's ion environment

Abstract

73P/Schwassmann-Wachmann 3 is a short-period comet that has undergone multiple fragmentation events in the last few decades. During May-June 2006, while passing near Earth, multiple fragments of comet 73P passed sunward of Sun-Earth Lagrange Point 1, while cometary pickup ions were detected concurrently by instruments on both the ACE and Wind spacecraft, implying the crossing of one or more ion tail. Additionally, during August 2011, a fragment of 73P passed directly sunward of spacecraft STEREO-B. A detection of cometary ions is shown to originate at fragment 73P-AM. Solar wind velocity measurements are used to extrapolate the flow of the solar wind in 3 dimensions and, when compared with the positions of known comets and cometary fragments, estimate the separation between the cometary ion tail and the spacecraft. Using this technique, it is shown that the alignment of the major cometary fragments with the spacecraft was poor for the transport of cometary ions via the solar wind, but the encounter was near enough for immersion in the diffuse ion tail surrounding an extended dust trail within which the nucleus fragments reside. This implies that, at this distance, the extended trail of cometary debris was a significant source of cometary ions in the case of comet 73P.