Six Outbursts of Comet 46P/Wirtanen

Abstract

Cometary activity is a manifestation of sublimation-driven processes at the surface of nuclei. However, cometary outbursts may arise from other processes that are not necessarily driven by volatiles. In order to fully understand nuclear surfaces and their evolution, we must identify the causes of cometary outbursts. In that context, we present a study of mini-outbursts of comet 46P/Wirtanen. Six events are found in our long-term lightcurve of the comet around its perihelion passage in 2018. The apparent strengths range from $-0.2$ to $-1.6$ mag in a 5" radius aperture, and correspond to dust masses between $\sim 10^4$ to $10^6$ kg, but with large uncertainties due to the unknown grain size distributions. However, the nominal mass estimates are the same order of magnitude as the mini-outbursts at comet 9P/Tempel 1 and 67P/Churyumov-Gerasimenko, events which were notably lacking at comet 103P/Hartley 2. We compare the frequency of outbursts at the four comets, and suggest that the surface of 46P has large-scale ($\sim$10-100 m) roughness that is intermediate to that of 67P and 103P, if not similar to the latter. The strength of the outbursts appear to be correlated with time since the last event, but a physical interpretation with respect to solar insolation is lacking. We also examine Hubble Space Telescope images taken about 2 days following a near-perihelion outburst. No evidence for macroscopic ejecta was found in the image, with a limiting radius of about 2-m.

Accepted for publication in The Planetary Science Journal. 33 pages, 11 figures, 3 tables

References in corpus (15)

• The Zwicky Transient Facility: System Overview, Performance, and First Results
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The Zwicky Transient Facility: Science Objectives
• astroquery: An Astronomical Web-Querying Package in Python
• The Zwicky Transient Facility: Surveys and Scheduler
• Summer fireworks on comet 67P
• Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 3
• Constraints on cometary surface evolution derived from a statistical analysis of 67P's topography
• Outburst and Splitting of Interstellar Comet 2I/Borisov
• Mt. Wendelstein Imaging of the Post-Perihelion Dust Coma of 67P/Churyumov-Gerasimenko in 2015/2016
• Fragmentation Kinematics in Comet 332P/Ikeya-Murakami
• 2014-2015 Multiple Outbursts of 15P/Finlay
• Local manifestations of cometary activity
• Modeling of the outburst on July 29th, 2015 observed with OSIRIS cameras in the southern hemisphere of comet 67P/Churyumov-Gerasimenko
• Monitoring polarization in comet 46P/Wirtanen

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• Enlargement of depressions on comet 81P/Wild 2: Constraint based on 30-year cometary activity in the inner Solar System