Cassini UVIS observations of the Io plasma torus. IV. Modeling temporal and azimuthal variability
TL;DR: In this article, the authors presented a model of the remarkable temporal and azimuthal variability of the Io plasma torus observed during the Cassini encounter with Jupiter, where the authors postulate the existence of two azimated variations in the number of superthermal electrons in the torus: a primary variation with a period of 10.07 h and a secondary variation that remains fixed in System III longitude.
About: This article is published in Icarus.The article was published on 2008-03-01 and is currently open access. It has received 83 citations till now. The article focuses on the topics: Torus.
Citations
More filters
TL;DR: In this paper, the authors present simple models of the plasma disks surrounding Jupiter and Saturn based on published measurements of plasma properties, and calculate radial profiles of the distribution of plasma mass, pressure, thermal energy density, kinetic energy density and energy density of the suprathermal ion populations.
Abstract: [1] We present simple models of the plasma disks surrounding Jupiter and Saturn based on published measurements of plasma properties. We calculate radial profiles of the distribution of plasma mass, pressure, thermal energy density, kinetic energy density, and energy density of the suprathermal ion populations. We estimate the mass outflow rate as well as the net sources and sinks of plasma. We also calculate the total energy budget of the system, estimating the total amount of energy that must be added to the systems at Jupiter and Saturn, though the causal processes are not understood. We find that the more extensive, massive disk of sulfur- and oxygen-dominated plasma requires a total input of 3–16 TW to account for the observed energy density at Jupiter. At Saturn, neutral atoms dominate over the plasma population in the inner magnetosphere, and local source/loss process dominate over radial transport out to 8 RS, but beyond 8–10 RS about 75–630 GW needs to be added to the system to heat the plasma.
292 citations
TL;DR: Jupiter: The Planet, Satellites and Magnetosphere (JPLM) as discussed by the authors is an encyclopedic volume that summarizes current knowledge of the Jovian system.
Abstract: In June 2001, with the Galileo mission ending and the Cassini mission having encountered Jupiter on its way to Saturn, a conference (titled “Jupiter: The Planet, Satellites and Magnetosphere,” sponsored by NASA, the Jet Propulsion Laboratory, Ball Aerospace, Southwest Research Institute, and the University of Colorado) was held on 25–30 June 2001, in Boulder, Colorado, to provide a framework for generating a comprehensive volume that would summarize current knowledge of the Jovian system. Three years later, this encyclopedic volume, Jupiter: The Planet, Satellites and Magnetosphere, was published, presenting an impressive detailed guide for understanding this complex system.
247 citations
University of Colorado Boulder1, INAF2, Southwest Research Institute3, University of Texas at San Antonio4, University of Liège5, University of Leicester6, Goddard Space Flight Center7, Planetary Science Institute8, University of Iowa9, Jet Propulsion Laboratory10, Johns Hopkins University11, University of California, Los Angeles12, Centre national de la recherche scientifique13
TL;DR: Junior as discussed by the authors is the first spacecraft to enter polar orbit of Jupiter and venture deep into unexplored polar territories of the magnetosphere, where it carries a range of instruments that take particles and fields measurements, remote sensing observations of auroral emissions at UV, visible, IR and radio wavelengths, and detect microwave emission from Jupiter's radiation belts.
Abstract: In July 2016, NASA’s Juno mission becomes the first spacecraft to enter polar orbit of Jupiter and venture deep into unexplored polar territories of the magnetosphere. Focusing on these polar regions, we review current understanding of the structure and dynamics of the magnetosphere and summarize the outstanding issues. The Juno mission profile involves (a) a several-week approach from the dawn side of Jupiter’s magnetosphere, with an orbit-insertion maneuver on July 6, 2016; (b) a 107-day capture orbit, also on the dawn flank; and (c) a series of thirty 11-day science orbits with the spacecraft flying over Jupiter’s poles and ducking under the radiation belts. We show how Juno’s view of the magnetosphere evolves over the year of science orbits. The Juno spacecraft carries a range of instruments that take particles and fields measurements, remote sensing observations of auroral emissions at UV, visible, IR and radio wavelengths, and detect microwave emission from Jupiter’s radiation belts. We summarize how these Juno measurements address issues of auroral processes, microphysical plasma physics, ionosphere-magnetosphere and satellite-magnetosphere coupling, sources and sinks of plasma, the radiation belts, and the dynamics of the outer magnetosphere. To reach Jupiter, the Juno spacecraft passed close to the Earth on October 9, 2013, gaining the necessary energy to get to Jupiter. The Earth flyby provided an opportunity to test Juno’s instrumentation as well as take scientific data in the terrestrial magnetosphere, in conjunction with ground-based and Earth-orbiting assets.
192 citations
Additional excerpts
...Steffl et al. (2008) showed that a small (<1...
[...]
TL;DR: In this article, the ionospheric response to auroral precipitation at the giant planets is reviewed, using models and observations The emission processes for aurorae at radio, infrared, visible, ultraviolet, and X-ray wavelengths are described, and exemplified using ground-and space-based observations Comparisons between the emissions at different wavelengths are made, where possible, and interpreted in terms of precipitating particle characteristics or atmospheric conditions.
Abstract: The ionospheric response to auroral precipitation at the giant planets is reviewed, using models and observations The emission processes for aurorae at radio, infrared, visible, ultraviolet, and X-ray wavelengths are described, and exemplified using ground- and space-based observations Comparisons between the emissions at different wavelengths are made, where possible, and interpreted in terms of precipitating particle characteristics or atmospheric conditions Finally, the spatial distributions and dynamics of the various components of the aurorae (moon footprints, low-latitude, main oval, polar) are related to magnetospheric processes and boundaries, using theory, in situ, and remote observations, with the aim of distinguishing between those related to internally-driven dynamics, and those related to the solar wind interaction
95 citations
Cites background from "Cassini UVIS observations of the Io..."
...The beating originates from a peak of the hot electron population density near 290◦ of longitude (Steffl et al.2008) caused by an Io-like interaction powered by empty flux tubes moving inward in the torus (Hess et al.2011b)....
[...]
TL;DR: The PLS data provided a survey of the plasma properties between approx 5 and 30 Jupiter radii [R(sub J)] in the equatorial region as mentioned in this paper, showing that the density decreases with radial distance by nearly 5 orders of magnitude.
Abstract: The plasma science (PLS) Instrument on the Galileo spacecraft (orbiting Jupiter from December 1995 to September 2003) measured properties of the ions that were trapped in the magnetic field The PLS data provide a survey of the plasma properties between approx 5 and 30 Jupiter radii [R(sub J)] in the equatorial region We present plasma properties derived via two analysis methods: numerical moments and forward modeling We find that the density decreases with radial distance by nearly 5 orders of magnitude from approx 2 to 3000 cm(exp-3) at 6R(sub j) to approx 005cm(sub -3) at 30 R(sub j) The density profile did not show major changes from orbit to orbit, suggesting that the plasma production and transport remained constant within about a factor of 2 The radial profile of ion temperature increased with distance which implied that contrary to the concept of adiabatic cooling on expansion, the plasma heats up as it expands out from Io's orbit (where TI is approx60-80 eV) at approx 6R(sub j) to a few keV at 30R(sub j)There does not seem to be a long-term, systematic variation in ion temperature with either local time or longitude This latter finding differs from earlier analysis of Galileo PLS data from a selection of orbits Further examination of all data from all Galileo orbits suggests that System Ill variations are transitory on timescales of weeks, consistent with the modeling of Cassini Ultraviolet Imaging Spectrograph observations The plasma flow is dominated by azimuthal flow that is between 80% and 100% of corotation out to 25 R(sub j)
85 citations
References
More filters
Book•
31 Jan 1986TL;DR: Numerical Recipes: The Art of Scientific Computing as discussed by the authors is a complete text and reference book on scientific computing with over 100 new routines (now well over 300 in all), plus upgraded versions of many of the original routines, with many new topics presented at the same accessible level.
Abstract: From the Publisher:
This is the revised and greatly expanded Second Edition of the hugely popular Numerical Recipes: The Art of Scientific Computing. The product of a unique collaboration among four leading scientists in academic research and industry, Numerical Recipes is a complete text and reference book on scientific computing. In a self-contained manner it proceeds from mathematical and theoretical considerations to actual practical computer routines. With over 100 new routines (now well over 300 in all), plus upgraded versions of many of the original routines, this book is more than ever the most practical, comprehensive handbook of scientific computing available today. The book retains the informal, easy-to-read style that made the first edition so popular, with many new topics presented at the same accessible level. In addition, some sections of more advanced material have been introduced, set off in small type from the main body of the text. Numerical Recipes is an ideal textbook for scientists and engineers and an indispensable reference for anyone who works in scientific computing. Highlights of the new material include a new chapter on integral equations and inverse methods; multigrid methods for solving partial differential equations; improved random number routines; wavelet transforms; the statistical bootstrap method; a new chapter on "less-numerical" algorithms including compression coding and arbitrary precision arithmetic; band diagonal linear systems; linear algebra on sparse matrices; Cholesky and QR decomposition; calculation of numerical derivatives; Pade approximants, and rational Chebyshev approximation; new special functions; Monte Carlo integration in high-dimensional spaces; globally convergent methods for sets of nonlinear equations; an expanded chapter on fast Fourier methods; spectral analysis on unevenly sampled data; Savitzky-Golay smoothing filters; and two-dimensional Kolmogorov-Smirnoff tests. All this is in addition to material on such basic top
12,662 citations
Book•
26 Feb 1988
TL;DR: The Diskette v 2.04, 3.5'' (720k) for IBM PC, PS/2 and compatibles [DOS] Reference Record created on 2004-09-07, modified on 2016-08-08.
Abstract: Note: Includes bibliographical references and index.- Diskette v 2.04, 3.5'' (720k) for IBM PC, PS/2 and compatibles [DOS] Reference Record created on 2004-09-07, modified on 2016-08-08
9,345 citations
TL;DR: This paper studies the reliability and efficiency of detection with the most commonly used technique, the periodogram, in the case where the observation times are unevenly spaced to retain the simple statistical behavior of the evenly spaced case.
Abstract: Detection of a periodic signal hidden in noise is frequently a goal in astronomical data analysis This paper does not introduce a new detection technique, but instead studies the reliability and efficiency of detection with the most commonly used technique, the periodogram, in the case where the observation times are unevenly spaced This choice was made because, of the methods in current use, it appears to have the simplest statistical behavior A modification of the classical definition of the periodogram is necessary in order to retain the simple statistical behavior of the evenly spaced case With this modification, periodogram analysis and least-squares fitting of sine waves to the data are exactly equivalent Certain difficulties with the use of the periodogram are less important than commonly believed in the case of detection of strictly periodic signals In addition, the standard method for mitigating these difficulties (tapering) can be used just as well if the sampling is uneven An analysis of the statistical significance of signal detections is presented, with examples
6,761 citations
"Cassini UVIS observations of the Io..." refers methods in this paper
...Careful analysis of the UVIS observations using Lomb–Scargle periodograms (Lomb, 1976; Scargle, 1982; Horne and Baliunas, 1986) confirmed strong torus periodicity with a period of 10.07 h (see Fig....
[...]
Book•
01 Jan 1989
TL;DR: In this paper, a comparison of theory with observations internal dynamics of gaseous nebulae interstellar dust H II regions in the galactic context is presented. But the results are limited to the case of active galactic nuclei.
Abstract: Photoionization equilibrium thermal equilibrium calculation of emitted spectrum comparison of theory with observations internal dynamics of gaseous nebulae interstellar dust H II regions in the galactic context planetary nebulae nova and supernova remnants active galactic nuclei - diagnostic and physics active galactic nuclei - results.
6,090 citations