scholarly journals Six observational pieces of evidence against corotation as the main cause for the aurora at Jupiter

2020 ◽  
Author(s):  
Bertrand Bonfond ◽  
Zhonghua Yao ◽  
Denis Grodent
Keyword(s):  
Magnetic Field ◽  
Hubble Space Telescope ◽  
Current System ◽  
Charged Particles ◽  
Continuous Ring ◽  
Jovian Magnetosphere ◽  
Magnetic Loading ◽  
Auroral Emissions ◽  
Magnetic Poles ◽  
A Current

<p>The Main Emissions are the most recognizable feature of the aurorae at Jupiter and they are responsible for roughly 1/3rd of the total emitted power. They form an ever-present and quasi-continuous ring of emission centered on the magnetic poles. The most widely accepted explanation for these auroral emissions involves a current system related to the corotation enforcement of the plasma in the Jovian magnetosphere. Models based on this theory explain many characteristics of the aurorae. However, recent observations from the NASA Juno spacecraft and the ESA/NASA Hubble Space Telescope, complemented by previous results from the NASA Galileo spacecraft, challenge this theoretical framework. In this presentation, we will review six specific sets of observations contradictory with expectations from the corotation enforcement theory:</p> <ol> <li> dawn/dusk asymmetries in the particle angular velocity and magnetic field bend-back,</li> <li>fragmented and asymmetric field-aligned currents,</li> <li>dawn/dusk brightness asymmetry,</li> <li>global auroral brightening in response to solar wind compression,</li> <li>auroral brightness variations as a response to magnetic loading/unloading,</li> <li>energy distribution of the charged particles precipitating into the main auroral emissions.</li> </ol> <p>We will expose their implications for the modelling of the Jovian magnetosphere and aurorae and we will discuss promising paths forward. </p>

scholarly journals Magnetospheric magnetic field modelling for the 2011 and 2012 HST Saturn aurora campaigns – implications for auroral source regions

2014 ◽  
Vol 32 (6) ◽  
pp. 689-704 ◽  
Author(s):  
E. S. Belenkaya ◽  
S. W. H. Cowley ◽  
C. J. Meredith ◽  
J. D. Nichols ◽  
V. V. Kalegaev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ring Current ◽  
Hubble Space Telescope ◽  
Current System ◽  
Outer Edge ◽  
Local Times ◽  
Closed Field ◽  
Principal Connection ◽  
Magnetic Field Model ◽  
Field Lines

Abstract. A unique set of images of Saturn's northern polar UV aurora was obtained by the Hubble Space Telescope in 2011 and 2012 at times when the Cassini spacecraft was located in the solar wind just upstream of Saturn's bow shock. This rare situation provides an opportunity to use the Kronian paraboloid magnetic field model to examine source locations of the bright auroral features by mapping them along field lines into the magnetosphere, taking account of the interplanetary magnetic field (IMF) measured near simultaneously by Cassini. It is found that the persistent dawn arc maps to closed field lines in the dawn to noon sector, with an equatorward edge generally located in the inner part of the ring current, typically at ~ 7 Saturn radii (RS) near dawn, and a poleward edge that maps variously between the centre of the ring current and beyond its outer edge at ~ 15 RS, depending on the latitudinal width of the arc. This location, together with a lack of response in properties to the concurrent IMF, suggests a principal connection with ring-current and nightside processes. The higher-latitude patchy auroras observed intermittently near to noon and at later local times extending towards dusk are instead found to straddle the model open–closed field boundary, thus mapping along field lines to the dayside outer magnetosphere and magnetopause. These emissions, which occur preferentially for northward IMF directions, are thus likely associated with reconnection and open-flux production at the magnetopause. One image for southward IMF also exhibits a prominent patch of very high latitude emissions extending poleward of patchy dawn arc emissions in the pre-noon sector. This is found to lie centrally within the region of open model field lines, suggesting an origin in the current system associated with lobe reconnection, similar to that observed in the terrestrial magnetosphere for northward IMF.

scholarly journals Modeling of the Jovian Magnetosphere

2005 ◽  
Vol 23 (3) ◽  
pp. 809-826 ◽  
Author(s):  
I. I. Alexeev ◽  
E. S. Belenkaya
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Component ◽  
Current System ◽  
Dynamic Pressure ◽  
High Latitudes ◽  
Jovian Magnetosphere ◽  
Wind Influence ◽  
Magnetospheric Field ◽  
Normal Magnetic Field

Abstract. This paper presents a global model of the Jovian magnetosphere which is valid not only in the equatorial plane and near the planet, as most of the existing models are, but also at high latitudes and in the outer regions of the magnetosphere. The model includes the Jovian dipole, magnetodisc, and tail current system. The tail currents are combined with the magnetopause closure currents. All inner magnetospheric magnetic field sources are screened by the magnetopause currents. It guarantees a zero normal magnetic field component for the inner magnetospheric field at the whole magnetopause surface. By changing magnetospheric scale (subsolar distance), the model gives a possibility to study the solar wind influence on the magnetospheric structure and auroral activity. A dependence of the magnetospheric size on the solar wind dynamic pressure psw (proportional to psw-0.23) is obtained. It is a stronger dependence than in the case of the Earth's magnetosphere (psw-1/6). The model of Jupiter's magnetospheric which is presented is a unique one, as it allows one to study the solar wind and interplanetary magnetic field (IMF) effects.

scholarly journals Hubble Space Telescope Observations of Galilean Satellites

2002 ◽  
Vol 12 ◽  
pp. 618 ◽  
Author(s):  
Melissa A. McGrath
Keyword(s):  
Hubble Space Telescope ◽  
Galilean Satellites ◽  
Space Telescope ◽  
Spatially Resolved ◽  
Jovian Magnetosphere ◽  
Solar System Objects ◽  
Satellites Of Jupiter ◽  
Imaging And Spectroscopy ◽  
Auroral Emissions ◽  
Scientific Return

AbstractOne of the premier areas of scientific return from Hubble Space Telescope (HST) observations of Solar System objects has been studies of the Galilean satellites of Jupiter. Because these objects are unresolvable in most ground-based observations, HST’s spatially resolved imaging and spectroscopy of their surfaces, atmospheres, and electrodynamic interactions with the Jovian magnetosphere have provided unique results. This talk will review highlights of the science results from HST observations of the Galilean satellites, including discovery of auroral emissions at the poles of Ganymede, the recent discovery of molecular sulfur in the Pele plume on Io, and the presence of SO2in the surface of Callisto.

Study of MFM Application in Semiconductor Failure Analysis

2004 ◽  
Author(s):  
Way-Jam Chen ◽  
Lily Shiau ◽  
Ming-Ching Huang ◽  
Chia-Hsing Chao
Keyword(s):  
Magnetic Field ◽  
Failure Analysis ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Current Flow ◽  
Force Microscopy ◽  
The Magnetic Field ◽  
A Current

Abstract In this study we have investigated the magnetic field associated with a current flowing in a circuit using Magnetic Force Microscopy (MFM). The technique is able to identify the magnetic field associated with a current flow and has potential for failure analysis.

scholarly journals 46. The störmertron

1958 ◽  
Vol 6 ◽  
pp. 446-447
Author(s):  
Willard H. Bennett
Keyword(s):  
Magnetic Field ◽  
Charged Particles ◽  
Mercury Vapor ◽  
Electron Gun ◽  
Conducting Film ◽  
New Developments ◽  
Electrically Conducting ◽  
The Earth ◽  
Magnetic Dipole Field ◽  
Glass Tubes

A tube has been developed in which the shapes of streams of charged particles moving in the earth's magnetic field can be produced accurately to scale. The tube has been named the Störmertron in honor of Carl Störmer who calculated many such orbits. New developments which have made this tube possible include a method for coating the inside of large glass tubes with a transparent electrically conducting film, and an electron gun producing gas-focused streams in less than ½ micron of mercury vapor, a nearly vapor-free grease joint, and a nearly vapor-free carbon black. The magnetic dipole field of the earth is simulated with an Alnico magnet capped with properly shaped soft iron caps. The stream is deflected using two pairs of yoke coils near the gun.

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