EUV observation from the Earth-orbiting satellite, EXCEED

Yoshioka, Kazuo; Murakami, Go; Yoshikawa, Ichiro; Ueno, Munetaka; Uemizu, Kazunori; Yamazaki, Atsushi

doi:10.1016/j.asr.2009.10.002

Cited by 19 publications

(8 citation statements)

References 30 publications

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“…An EUV spectroscope to be on board the Earth‐orbiting satellite SPRINT‐A/EXCEED scheduled to be launched in 2013 is now under development by the University of Tokyo and Tohoku University, along with the Institute of Space and Astronautical Science, part of the Japan Aerospace Exploration Agency [ Yoshikawa et al , 2011; Yoshioka et al , 2010]. The effective area of the SPRINT‐A/EXCEED is about 500 times larger than that of the Cassini/UVIS.…”

Section: Discussionmentioning

confidence: 99%

Hot electron component in the Io plasma torus confirmed through EUV spectral analysis

et al. 2011

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[1] The Io plasma torus is composed mainly of sulfur and oxygen ions and their compounds, together with a background of electrons. In addition to those basic components, several in situ observations have shown that a small percentage of the electrons there have been excited to be as much as 100 times hotter than the background electrons. They have a significant impact on the energy balance in the Jovian inner magnetosphere. However, their generation process has not yet been clarified. One difficulty is that the available data about the hot electrons all come from in situ observations which cannot explore the temporal and spatial distributions explicitly. Therefore, remote sensing which can take a direct picture of the plasma dynamics is necessary in order to clarify the hot electron problem. In this study, a plasma diagnosis method was used for the Io plasma torus EUV spectra taken from the Cassini spacecraft. Agreement with previous observations confirmed the background electron temperature and ion compositions as determined by our model. In addition, the available data are matched even better when the model is run with a hot electron component. This consistent confirmation by remote sensing is a first. Because of the limited temporal resolution and observational coverage, the results could not be used to explain the generation process of the hot electrons. However, we expect that this method will be useful in studying the hot electron generation process when data from future missions with better temporal resolution and more complete coverage become available.

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Section: Discussionmentioning

confidence: 99%

Hot electron component in the Io plasma torus confirmed through EUV spectral analysis

et al. 2011

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“…Spectral observation in the VUV range is effective for the identification and determination of abundances of hydrocarbon species in space; VUV spectra thus provide a powerful means that has been applied during spacecraft missions (Broadfoot et al 1977;Esposito et al 2004;Ajello et al 2005;Yoshioka et al 2010). As part of the NASA Cassini-Huygens Mission, for example, the Cassini Ultraviolet Imaging Spectrograph (UVIS) included channels for extreme-ultraviolet (EUV) and far-ultraviolet (FUV) spectral imaging (Esposito et al 2004) to record VUV spectra of targets in the exploration of the Saturn system Shemansky et al 2005).…”

Section: Resultsmentioning

confidence: 99%

ABSORPTION CROSS SECTION OF GASEOUS ACETYLENE AT 85 K IN THE WAVELENGTH RANGE 110-155 nm

Cheng¹,

Chen²,

Lu³

et al. 2011

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Absorption spectra and absorption cross sections of gaseous acetylene, C 2 H 2 , at 298 and 85 K were measured in the wavelength range 110-155 nm with a slit-jet system coupled to a synchrotron as a source of vacuum ultraviolet light. Using published spectral parameters of C 2 H 2 , we simulated the absorption profile for the Rydberg transition to state 4R 0 in the range 124.6-125.1 nm, according to which the temperature of the jet-expanded sample at stagnation pressure 200 Torr is 85 ± 5 K. Our cross sections of C 2 H 2 are applicable for determining properties sensitive to temperature for diagnostic work on Saturn and Titan.

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“…It is not difficult to handle the sulfur lines in the data analysis because they are not contaminated by geocoronal emissions or terrestrial airglow. However, for oxygen ions we have to carefully remove the foreground contamination [ Yoshioka et al ., ]. Terrestrial airglow of oxygen ion at 83.4 nm is produced via photoionization/excitation by EUV sunlight and ionization/excitation of atomic oxygen by photoelectron impact, and resonant scattering of solar light [ Kumar et al ., ; Meier , ].…”

Section: Spectroscopic Observation By Exceed On Hisakimentioning

confidence: 99%

Radial variation of sulfur and oxygen ions in the Io plasma torus as deduced from remote observations by Hisaki

et al. 2017

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The Io plasma torus, situated in the Jovian inner magnetosphere (6–8 Jovian radii from the planet) is filled with heavy ions and electrons, a large part of which are derived from Io's volcanos. The torus is the key area connecting the primary source of plasma (Io) with the midmagnetosphere (>10 Jovian radii), where highly dynamic phenomena are taking place. Revealing the plasma behavior of the torus is a key factor in elucidating Jovian magnetospheric dynamics. A global picture of the Io plasma torus can be obtained via spectral diagnosis of remotely sensed ion emissions generated via electron impact excitation. Hisaki, an Earth‐orbiting spacecraft equipped with an extreme ultraviolet spectrograph Extreme Ultraviolet Spectroscope for Exospheric Dynamics, has observed the torus at moderate spectral resolution. The data have been submitted to spectral analysis and physical chemistry modeling under the assumption of axial symmetry. Results from the investigation are radial profiles of several important parameters including electron density and temperature as well as ion abundances. The inward transport timescale of midmagnetospheric plasma is obtained to be 2–40 h from the derived radial profile for the abundance of suprathermal electrons. The physical chemistry modeling results in a timescale for the outward transport of Io‐derived plasma of around 30 days. The ratio between inward and outward plasma speed (~1%) is consistent with the occurrence rate of depleted flux tubes determined using in situ observations by instruments on the Galileo spacecraft.

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EUV observation from the Earth-orbiting satellite, EXCEED

Cited by 19 publications

References 30 publications

Hot electron component in the Io plasma torus confirmed through EUV spectral analysis

Hot electron component in the Io plasma torus confirmed through EUV spectral analysis

ABSORPTION CROSS SECTION OF GASEOUS ACETYLENE AT 85 K IN THE WAVELENGTH RANGE 110-155 nm

Radial variation of sulfur and oxygen ions in the Io plasma torus as deduced from remote observations by Hisaki

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