Discovery of hotspots on Io using disk-resolved infrared imaging

Spencer, J. R.; Shure, M. A.; Ressler, Michael E.; Goguen, J. D.; Sinton, William M.; Toomey, Douglas W.; Denault, Anthony J.; Westfall, J. E.

doi:10.1038/348618a0

Cited by 45 publications

(29 citation statements)

References 16 publications

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“…One can observe Io in the infrared while in eclipse, so that it only "glows" via its hot spots (Veeder et al 1994). Another approach is to use Io's occultations/eclipses by Jupiter (Spencer et al 1990) or by another satellite (Goguen et al 1988, Descamps et al 1992). These mutual events, which only occured every six years, were used to derive approximate positions and temperature information for some individual hot spots.…”

Section: Introductionmentioning

confidence: 98%

High-Resolution Keck Adaptive Optics Imaging of Violent Volcanic Activity on Io

Marchis

2002

Icarus

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Section: Introductionmentioning

confidence: 98%

High-Resolution Keck Adaptive Optics Imaging of Violent Volcanic Activity on Io

Marchis

2002

Icarus

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“…Direct imaging under excellent seeing condition and when Io is in Jupiter's shadow [Spencer et al, 1990] occasionally permitted direct "seeing" of the brightest hot spots on Jupiter's facing hemisphere. We must mention that most of these techniques can only be applied to this hemisphere and that the other hemisphere is mostly unstudied from Earth.…”

mentioning

confidence: 99%

A survey of Io's volcanism by adaptive optics observations in the 3.8‐μm thermal band (1996–1999)

Marchis¹,

Prangé²,

Fusco³

2001

J. Geophys. Res.

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Abstract. In this study, we analyze a series of images of Io obtained with theEuropean Southern Observatory adaptive optics system (Adaptive Optics Near Infrared System, ADONIS) at 3.8 tzrn from 1996 to 1999, with particular emphasis on the observations carried out in late 1999 in support of the Galileo fiybys of Io. Use of a new myopic deconvolution method, Myopic Iterative Step Preserving Algorithm (MISTRAL), especially designed for planetary objects, significantly improves the quality and the reliability of the reconstructed images. Using a simulation of artificial images of Io, we estimate the extent to which this algorithm is able to prevent noise amplification, to better restore sharp edges, and to preserve the initial photometry. Once this a•lgorithm has been applied to our data and the solar-reflected background has been subtracted, we have 89 images of Io available for search and temporal survey of the hot spots over 4 years. In most cases, the data, acquired during two consecutive nights, provide an almost global view of the surface of Io. We identify 20 hot spots for which we determine the coordinates and the brightness at 3.8 tzrn (as a function of time). More than half of the hot spots were detected on all the images and were considered as persistent. Particular emphasis has been put on the brightest two hot spots, Loki and Pele, for which we obtain a center-to-limb variation curve (a cosine curve for Loki and a curve decreasing slightly faster than a cosine law for Pele with possible physical interpretations).

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“…Such measurements present perhaps the best means for identifying regions of active geologic activity. Indeed, active hotspots persist at both the "tiger stripes" of Enceladus (Spencer et al 2006) and the volcanoes of Io (Pearl & Sinton 1982;Spencer et al 1990). In addition, Cassini thermal observations of Saturn's moons Mimas and Tethys have shown that temperature measurements can reveal details on the effects of magnetospheric particle bombardment on surface texture (Howett et al 2011(Howett et al , 2012.…”

Section: Introductionmentioning

confidence: 99%

ALMA Thermal Observations of Europa

Trumbo

Brown

Butler

2018

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We present four daytime thermal images of Europa taken with the Atacama Large Millimeter Array. Together, these images comprise the first spatially resolved thermal data set with complete coverage of Europa's surface. The resulting brightness temperatures correspond to a frequency of 233 GHz (1.3 mm) and a typical linear resolution of roughly 200 km. At this resolution, the images capture spatially localized thermal variations on the scale of geologic and compositional units. We use a global thermal model of Europa to simulate the ALMA observations in order to investigate the thermal structure visible in the data. Comparisons between the data and model images suggest that the large-scale daytime thermal structure on Europa largely results from bolometric albedo variations across the surface. Using bolometric albedos extrapolated from Voyager measurements, a homogenous model reproduces these patterns well, but localized discrepancies exist. These discrepancies can be largely explained by spatial inhomogeneity of the surface thermal properties. Thus, we use the four ALMA images to create maps of the surface thermal inertia and emissivity at our ALMA wavelength. From these maps, we identify a region of either particularly high thermal inertia or low emissivity near 90°west and 23°north, which appears anomalously cold in two of our images.

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Discovery of hotspots on Io using disk-resolved infrared imaging

Cited by 45 publications

References 16 publications

High-Resolution Keck Adaptive Optics Imaging of Violent Volcanic Activity on Io

High-Resolution Keck Adaptive Optics Imaging of Violent Volcanic Activity on Io

A survey of Io's volcanism by adaptive optics observations in the 3.8‐μm thermal band (1996–1999)

ALMA Thermal Observations of Europa

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