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Six Outbursts of Comet 46P/Wirtanen

Kelley, Michael S. P. and Farnham, Tony L. and Li, Jian-Yang and Bodewits, Dennis and Snodgrass, Colin and Allen, Johannes and Bellm, Eric C. and Coughlin, Michael W. and Drake, Andrew J. and Duev, Dmitry A. and Graham, Matthew J. and Kupfer, Thomas and Masci, Frank J. and Reiley, Dan and Walters, Richard and Dominik, M. and Jørgensen, U. G. and Andrews, A. E. and Bach-Møller, N. and Bozza, V. and Burgdorf, M. J. and Campbell-White, J. and Dib, S. and Fujii, Y. I. and Hinse, T. C. and Hundertmark, M. and Khalouei, E. and Longa-Peña, P. and Rabus, M. and Rahvar, S. and Sajadian, S. and Skottfelt, J. and Southworth, J. and Tregloan-Reed, J. and Unda-Sanzana, E. (2021) Six Outbursts of Comet 46P/Wirtanen. Planetary Science Journal, 2 (4). Art. No. 131. ISSN 2632-3338. doi:10.3847/PSJ/abfe11.

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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 ~10⁴ and 10⁶ kg, but with large uncertainties due to the unknown grain size distributions. However, the nominal mass estimates are on the same order of magnitude as the mini-outbursts at comet 9P/Tempel 1 and 67P/Churyumov-Gerasimenko, events that 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 (~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 two days following a near-perihelion outburst. No evidence for macroscopic ejecta was found in the image, with a limiting radius of about 2 m.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kelley, Michael S. P.0000-0002-6702-7676
Farnham, Tony L.0000-0002-4767-9861
Li, Jian-Yang0000-0003-3841-9977
Bodewits, Dennis0000-0002-2668-7248
Snodgrass, Colin0000-0001-9328-2905
Bellm, Eric C.0000-0001-8018-5348
Coughlin, Michael W.0000-0002-8262-2924
Duev, Dmitry A.0000-0001-5060-8733
Graham, Matthew J.0000-0002-3168-0139
Kupfer, Thomas0000-0002-6540-1484
Masci, Frank J.0000-0002-8532-9395
Walters, Richard0000-0002-1835-6078
Dominik, M.0000-0002-3202-0343
Andrews, A. E.0000-0002-8552-3999
Bach-Møller, N.0000-0002-8799-0080
Bozza, V.0000-0003-4590-0136
Burgdorf, M. J.0000-0002-5854-4217
Hinse, T. C.0000-0001-8870-3146
Rabus, M.0000-0003-2935-7196
Southworth, J.0000-0002-3807-3198
Additional Information:© 2021. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2020 September 30; revised 2021 April 19; accepted 2021 May 3; published 2021 July 21. We thank D. Schleicher and M. Knight for contributing some Lowell 0.8 m telescope data, and B. Skiff and L. Wasserman for assisting with the Lowell observations. We appreciate the helpful comments from the manuscript referees. Support for this work was provided by the NASA Solar System Observations program (80NSSC20K0673), the Space Telescope Science Institute (HST-GO-15372), the National Science Foundation (PHY-2010970), the National Research Foundation (NRF; No. 2019R1I1A1A01059609), the MINEDUC-UA project ESR1795, the European Union H2020-MSCA-ITN-2019 under grant no. 860470 (CHAMELEON), and by the Novo Nordisk Foundation Interdisciplinary Synergy Program (NNF19OC0057374). This work is based on observations obtained with the Samuel Oschin Telescope 48 inch at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. This work is also based on observations obtained by the MiNDSTEp team with the Danish 1.54 m telescope at ESOs La Silla Observatory. This research is also based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. This research made use of Montage. It is funded by the National Science Foundation under grant No. ACI-1440620, and was previously funded by the National Aeronautics and Space Administration's Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology. This research has made use of data and services provided by the International Astronomical Union's Minor Planet Center. Facilities: PO:1.2m (ZTF) - , LO:0.8m - , Danish 1.54m Telescope - , HST (WFC3) - . Software: astropy (Astropy Collaboration et al. 2018), sbpy (Mommert et al. 2014), astroquery (Ginsburg et al. 2019), JPL Horizons (Giorgini et al. 1996), Aperture Photometry Tool (Laher et al. 2012), SEP (Barbary 2016), Ginga (Jeschke et al. 2013), DS9 (Joye & Mandel 2003), imexam (Sosey 2017), astroscrappy (McCully et al. 2018), Montage (Jacob et al. 2010), photutils (Bradley et al. 2021), calviacat (Kelley & Lister 2019).
Group:Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
National Research Foundation of Korea2019R1I1A1A01059609
Ministerio de Educación (Chile)ESR1795
European Research Council (ERC)860470
NovoNordisk FoundationNNF19OC0057374
ZTF partner institutionsUNSPECIFIED
Subject Keywords:Comets; Short period comets; Broad band photometry; Coma dust
Issue or Number:4
Classification Code:Unified Astronomy Thesaurus concepts: Comets (280); Short period comets (1452); Broad band photometry (184); Coma dust (2159)
Record Number:CaltechAUTHORS:20210603-122523607
Persistent URL:
Official Citation:Michael S. P. Kelley et al 2021 Planet. Sci. J. 2 131
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109367
Deposited By: George Porter
Deposited On:03 Jun 2021 23:43
Last Modified:02 Aug 2021 18:32

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