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Io’s Loki Patera: Modeling of three brightening events in 2013–2016

de Kleer, Katherine and de Pater, Imke (2017) Io’s Loki Patera: Modeling of three brightening events in 2013–2016. Icarus, 289 . pp. 181-198. ISSN 0019-1035. doi:10.1016/j.icarus.2017.01.038.

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Loki Patera is one of the most dramatically time-variable volcanic features on Io, exhibiting episodic brightening events every 1–3 years that may produce over 15% of Io’s global heat flow. We observed three such brightening events with adaptive optics imaging at the Keck and Gemini N telescopes over the course of 70 nights of observation in 2013–2016. The high cadence and multi-wavelength nature of the observations provides constraints on models for activity at Loki Patera. The Matson et al. (2006) model for Loki Patera as an overturning basaltic magma sea is adapted to fit the observations of all three events. In particular, we adjust the details of the overturn progression, and modify the lava thermal properties to include dependencies on temperature and porosity, to improve the fit to the data. The preferred models find overturn front propagation velocities of 1.2–1.7 km/day, corresponding to resurfacing rates of 1500–2200 m^2/s. The time intervals of 440–540 days between successive events are roughly consistent with the 540-day period calculated by Rathbun et al. (2002) for events prior to 2001. The best coverage was obtained for the 2016 brightening; model fits to this event require a lava bulk thermal conductivity of 0.55–0.75 W/m/K, with the best fit obtained for a value of ∼0.7 W/m/K and an average porosity that decreases during cooling. For all three events, the overturn front appears to propagate around the patera in the clockwise direction, opposite to what has been inferred for past brightening events. There is evidence that the overturn may be more complex than a single propagating wave, perhaps involving multiple simultaneous resurfacing waves as well as portions of the patera that are active even after the nominal bright phase has ended. The measured intensities are anomalously low when Loki Patera is viewed at high emission angles, suggestive of topographic shadowing due to a raised area or the edge of the depression in which the magma sea resides.

Item Type:Article
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URLURL TypeDescription
de Kleer, Katherine0000-0002-9068-3428
de Pater, Imke0000-0002-4278-3168
Additional Information:© 2017 Elsevier. Received 1 October 2016, Revised 7 January 2017, Accepted 26 January 2017, Available online 20 February 2017. The authors would like to thank A.G. Davies and J. Rathbun for valuable insight at many stages of this work. This research was partially supported by the National Science Foundation grant AST-1313485 to UC Berkeley and by the National Science Foundation Graduate Research Fellowship to K. de Kleer under Grant DGE-1106400. This work made use of the JPL Solar System Dynamics high-precision ephemerides through the HORIZONS system. Results are based in part on data obtained with the W.M. Keck Observatory, which is operated by the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Results are based in part on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil). The authors extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented would have been possible.
Group:Astronomy Department
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1106400
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Io; Volcanism; Infrared observations; Adaptive optics; Spectroscopy
Record Number:CaltechAUTHORS:20190424-103200188
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Official Citation:Katherine de Kleer, Imke de Pater, Io’s Loki Patera: Modeling of three brightening events in 2013–2016, Icarus, Volume 289, 2017, Pages 181-198, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94919
Deposited By: George Porter
Deposited On:24 Apr 2019 18:09
Last Modified:16 Nov 2021 17:08

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