2006 Fragmentation of Comet 73P/Schwassmann-Wachmann 3B Observed with Subaru/Suprime-Cam

TL;DR

This study analyzed Subaru images of comet 73P/Schwassmann-Wachmann 3B, detecting numerous mini-comets, estimating their sizes, and examining their distribution and activity, revealing insights into fragment ejection, size distribution, and potential survival as near-Earth objects.

Contribution

First detailed analysis of mini-comet distribution and size from Subaru images, including modified synchrone-syndyne analysis and insights into fragment activity and survival.

Findings

Detected at least 154 mini-comets with sizes 5-108 m.

Most mini-comets ejected during April 2006 outburst.

Size distribution follows a power-law with index -3.34.

Abstract

We analyzed the Subaru/Suprime-Cam images of 73P/Schwassmann-Wachmann 3B and detected no fewer than 154 mini-comets. We applied synchrone-syndyne analysis, modified for rocket effect analysis, to the mini-fragment spatial distribution. We found that most of these mini-comets were ejected from fragment B by an outburst occurring around 1 April 2006. The ratio of the rocket force to solar gravity was 7 to 23 times larger than that exerted on fragment B. No significant color variation was found. We examined the surface brightness profiles of all detected fragments and estimated the sizes of 154 fragments. We found that the radius of these mini-fragments was in the 5- to 108-m range (equivalent size of Tunguska impactor). The power-law index of the differential size distribution was q = -3.34 +/- 0.05. Based on this size distribution, we found that about 1-10% of the mass of fragment B was lost in the April 2006 outbursts. Modeling the cometary fragment dynamics revealed that it is likely that mini-fragments smaller than ~10-20 m could be depleted in water ice and become inactive, implying that decameter-sized comet fragments could survive against melting and remain as near-Earth objects. We attempted to detect the dust trail, which was clearly found in infrared wavelengths by Spitzer. No brightness enhancement brighter than 30.0 mag arcsec^-2 (3sigma) was detected in the orbit of fragment B.