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Three decades of Loki Patera observations

de Pater, Imke and de Kleer, Katherine and Davies, Ashley G. and Ádámkovics, Máté (2017) Three decades of Loki Patera observations. Icarus, 297 . pp. 265-281. ISSN 0019-1035. doi:10.1016/j.icarus.2017.03.016.

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We present observations of Io's Loki Patera taken with the 10-m Keck telescopes between 1998 and 2016. Adding these data to those published by Rathbun and Spencer (2006) and the Gemini data of de Kleer and de Pater (2016a, 2017) results in a database of 3.5–3.8 µm emission from Loki Patera over almost 3 decades. Data presented here contain adaptive optics (AO) observations of Io's sunlit hemisphere at wavelengths between 1.6 and 5 µm, AO observations of Io in eclipse at 2–5 µm, and non-AO observations of Io in eclipse at 1.6–12 µm. The non-AO data were taken in September of 1999, during the early phase of a brightening event that was documented by Howell et al. (2001). Dual-component Io Flow model (IFM) fits to our 1999 observations show a mostly cool lava crust over almost the entire patera floor, with a relatively small hotter component making up less than 1% of the total area, consistent with previous observations. The 30-year timeline of Loki Patera revealed that, after an apparent cessation of, or change in, brightening events in 2002, Loki Patera became active again in 2009. The more recent activity may have a slightly shorter periodicity than observed by Rathbun et al. (2002), and the direction of flow propagation appears to have reversed. Since 2009 the flow direction is in the clockwise direction, starting in the north or north-east corner and propagating along the patera towards the south-west. During the Galileo era the propagation was in the counter-clockwise direction, starting in the south-west and propagating towards the east. Both the 30-year timeline and the 1.6–12 µm spectrum that was obtained during the brightening event in 1999 agree well with Matson et al.’s (2006) overturning lava lake model, as modified by de Kleer and de Pater (2017).

Item Type:Article
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URLURL TypeDescription
de Pater, Imke0000-0002-4278-3168
de Kleer, Katherine0000-0002-9068-3428
Davies, Ashley G.0000-0003-1747-8142
Additional Information:© 2017 Elsevier. Received 28 November 2016, Revised 11 March 2017, Accepted 16 March 2017, Available online 21 March 2017. The data presented in this paper were obtained at the W.M. Keck Observatories. The Keck Telescopes are operated as a scientific partnership among 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. Our research was partially supported by the National Science Foundation, NSF grant AST-1313485 to UC Berkeley. Ashley Davies thanks the NASA Outer Planets Research and Planetary Geology and Geophysics Programs for support. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations of Ionian volcanoes from this Hawaiian volcano.
Group:Astronomy Department
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Io; Infrared Observations; Volcanism
Record Number:CaltechAUTHORS:20190424-103200555
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Official Citation:Imke de Pater, Katherine de Kleer, Ashley G. Davies, Máté Ádámkovics, Three decades of Loki Patera observations, Icarus, Volume 297, 2017, Pages 265-281, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94923
Deposited By: George Porter
Deposited On:24 Apr 2019 19:47
Last Modified:16 Nov 2021 17:08

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