Io: Eruptions at Pillan, and the time evolution of Pele and Pillan from 1996 to 2015
Abstract
Observations obtained with the near-infrared camera NIRC2, coupled to the adaptive optics system on the 10-m W.M. Keck II telescope on Mauna Kea, Hawaii, on 14 August 2007 revealed an active and highly-energetic eruption at Pillan at 245.2 ± 0.7°W and 8.5 ± 0.5°S. A one-temperature blackbody fit to the data revealed a (blackbody) temperature of 840 ± 40 K over an area of 17 km^2, with a total power output of ∼500 GW. Using Davies' (Davies, A.G. [1996]. Icarus 124(1), 45–61) Io Flow Model, we find that the oldest lava present is less than 1-2 h old, having cooled down from the eruption temperature of >1400 K to ∼710 K; this young hot lava suggests that an episode of lava fountaining was underway. In addition to an examination of this eruption, we present data of the Pele and Pillan volcanoes obtained with the same instrument and telescope from 2002 through 2015. These data reveal another eruption at Pillan on UT 28 June 2010. Model fits to this eruption yield a blackbody temperature of 600–700 K over an area of ∼60 km^2, radiating over 600 GW. On UT 18 February 2015 an energetic eruption was captured by the InfraRed Telescope Facility (IRTF) via mutual event occultations. The eruption took place at 242.7 ± 1°W and 12.4 ± 1°S, i.e., in the eastern part of Pillan Patera. Subsequent observations showed a gradual decrease in the intensity of the eruption. Images obtained with the Keck telescope on 31 March and 5 May 2015 revealed that the locations of the eruption had shifted by 120–160 km to the NW. In contrast to the episodicity of Pillan, Pele has been persistent, observed in every appropriate 4.7 μm observation. Pele was remarkably consistent in its thermal emission from the Galileo era through February 2002, when a blackbody temperature of 940 ± 40 K and an area of 6.5 km^2 was measured. Since that time, however, the radiant flux from what is likely a apparently large, overturning lava lake has gradually subsided over the next decade by a factor of ∼4, while the location of the thermal source was moving back and forth between areas roughly ∼100 km to the W of the 2002 location and an area roughly ∼100 km to the SE of the 2002 location.
Additional Information
© 2015 Elsevier. Received 28 April 2015, Revised 1 September 2015, Accepted 3 September 2015, Available online 25 September 2015. We are grateful to Alfred McEwen for his review and suggestions for improving this paper. Most of the data presented in this paper were obtained at the W.M. Keck Observatory. We thank Keith Matthews for donating us the first half of the 14 August 2007 night, before our prime target (Uranus) was visible. Two of the data sets presented here (3 April 2007 and 28 June 2010) were retrieved from the publicly available Keck Archive (PI: F. Marchis). 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. Several data sets were obtained at the Gemini North 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), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). Three datasets (2015 mutual occultation events) were obtained with the Infrared Telescope Facility (IRTF), which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration. Our research was partially supported by the National Science Foundation, NSF Grant AST-1313485 to UC Berkeley. Katherine de Kleer is supported by the National Science Foundation Graduate Research Fellowship under Grant DGE-1106400. Ashley Davies thanks the NASA Outer Planets Research and Planetary Geology and Geophysics Program for support under grants NMO710830 and NMO710931. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea 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.Additional details
- Eprint ID
- 94928
- Resolver ID
- CaltechAUTHORS:20190424-103201071
- W. M. Keck Foundation
- NNH14CK55B
- NASA
- AST-1313485
- NSF
- DGE-1106400
- NSF Graduate Research Fellowship
- NMO710830
- NASA
- NMO710931
- NASA
- Created
-
2019-04-24Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field