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Six Outbursts of Comet 46P/Wirtanen

Authors :
Kelley, Michael S. P.
Farnham, Tony L.
Li, Jian-Yang
Bodewits, Dennis
Snodgrass, Colin
Allen, Johannes
Bellm, Eric C.
Coughlin, Michael W.
Drake, Andrew J.
Duev, Dmitry A.
Graham, Matthew J.
Kupfer, Thomas
Masci, Frank J.
Reiley, Dan
Walters, Richard
Dominik, M.
Jørgensen, U. G.
Andrews, A.
Bach-Møller, N.
Bozza, V.
Burgdorf, M. J.
Campbell-White, J.
Dib, S.
Fujii, Y. I.
Hinse, T. C.
Hundertmark, M.
Khalouei, E.
Longa-Peña, P.
Rabus, M.
Rahvar, S.
Sajadian, S.
Skottfelt, J.
Southworth, J.
Tregloan-Reed, J.
Unda-Sanzana, E.
Publication Year :
2021

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 $\sim10^4$ 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.<br />Comment: Accepted for publication in The Planetary Science Journal. 33 pages, 11 figures, 3 tables

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2105.05826
Document Type :
Working Paper
Full Text :
https://doi.org/10.3847/PSJ/abfe11