Cassini Uvis Observations Of The Io Plasma Torus, Cassini Observations of Io Options

[ljk4-1]

Paper: astro-ph/0508055
Date: Mon, 1 Aug 2005 23:20:28 GMT (459kb)

Title: Cassini UVIS Observations of the Io Plasma Torus. III. Observations of
Temporal and Azimuthal Variability

Authors: A. J. Steffl, P. A. Delamere, F. Bagenal

Comments: 35 pages including 12 figures and 2 tables
\\

In this third paper in a series presenting observations by the Cassini
Ultraviolet Imaging Spectrometer (UVIS) of the Io plasma torus, we show
remarkable, though subtle, spatio-temporal variations in torus properties. The
Io torus is found to exhibit significant, near-sinusoidal variations in ion
composition as a function of azimuthal position. The azimuthal variation in
composition is such that the mixing ratio of S II is strongly correlated with
the mixing ratio of S III and the equatorial electron density and strongly
anti-correlated with the mixing ratios of both S IV and O II and the equatorial
electron temperature. Surprisingly, the azimuthal variation in ion composition
is observed to have a period of 10.07 hours--1.5% longer than the System III
rotation period of Jupiter, yet 1.3% shorter than the System IV period defined
by Brown (1995). Although the amplitude of the azimuthal variation of S III and
O II remained in the range of 2-5%, the amplitude of the S II and S IV
compositional variation ranged between 5-25% during the UVIS observations.
Furthermore, the amplitude of the azimuthal variations of S II and S IV appears
to be modulated by its location in System III longitude, such that when the
region of maximum S II mixing ratio (minimum S IV mixing ratio) is aligned with
a System III longitude of ~200 +/- 15 degrees, the amplitude is a factor of ~4
greater than when the variation is anti-aligned. This behavior can explain
numerous, often apparently contradictory, observations of variations in the
properties of the Io plasma torus with the System III and System IV coordinate
systems.

\\ ( http://arXiv.org/abs/astro-ph/0508055 , 459kb)

[ljk4-1]

Astrophysics, abstract
astro-ph/0603329

From: Kandis Lea Jessup [view email]

Date: Mon, 13 Mar 2006 22:04:36 GMT (689kb)

Sulfur Volcanism on Io

Authors: Kandis Lea Jessup, John R. Spencer, Roger Yelle

Comments: pages:44 figures: 7 tables:3

In February 2003, March 2003 and January 2004 Pele plume transmission spectra were obtained during Jupiter transit with Hubble's Space Telescope Imaging Spectrograph (STIS), using the 0.1 arcsec long slit and the G230LB grating. The STIS spectra covered the 2100-3100 A wavelength region and extended spatially along Io's limb both northward of Pele. The S2 and SO2 absorption signatures evident in the these data indicate that the gas signature at Pele was temporally variable, and that an S2 absorption signature was present ~ 12 deg. from the Pele vent near 6+/-5 S and 264 +/-15 W, suggesting the presence of another S2 bearing plume on Io. Contemporaneous with the spectral data, UV and visible-wavelength images of the plume were obtained in reflected sunlight with the Advanced Camera for Surveys (ACS) prior to Jupiter transit. The dust scattering recorded in these data provide an additional qualitative measure of plume activity on Io, indicating that the degree of dust scattering over Pele varied as a function of the date of observation, and that there were several other dust bearing plumes active just prior to Jupiter transit. We present constraints on the composition and variability of the gas abundances of the Pele plume as well as the plumes detected by ACS and recorded within the STIS data, as a function of time. We discuss the implications of these results for thermochemical conditions at the plume vents, and our understanding of plume eruption styles active on Io.

http://arxiv.org/abs/astro-ph/0603329

[ljk4-1]

Loki, Io: New groundbased observations and a model describing the change from periodic overturn

http://arxiv.org/abs/astro-ph/0605240

The abstract says that "Loki Patera is the most powerful [active] volcano in
the solar system."

How do they determine this?

[ljk4-1]

Paper: astro-ph/0605539

Date: Sun, 21 May 2006 21:15:46 GMT (97kb)

Title: Characterization of jovian plasma embedded dust particles

Authors: Amara L. Graps (INAF-IFSI, Rome, Italy)

Comments: 17 pages, 1 postscript figure, Planetary and Space Science (in
press), Collected papers of the Dusty Rings ISSI Workshop June, 2005. For
high resolution version, see:

http://www.mpi-hd.mpg.de/dustgroup/~graps/dustyplasma/

As the data from space missions and laboratories improve, a research domain
combining plasmas and charged dust is gaining in prominence. Our solar system
provides many natural laboratories such as planetary rings, comet comae and
tails, ejecta clouds around moons and asteroids, and Earth's noctilucent clouds
for which to closely study plasma-embedded cosmic dust.

One natural laboratory to study electromagnetically-controlled cosmic dust has
been provided by the Jovian dust streams and the data from the instruments
which were on board the Galileo spacecraft. Given the prodigious quantity of dust
poured into the Jovian magnetosphere by Io and its volcanoes resulting in the
dust streams, the possibility of dusty plasma conditions exist.

This paper characterizes the main parameters for those interested in studying
dust embedded in a plasma with a focus on the Jupiter environment. I show how to
distinguish between dust-in-plasma and dusty-plasma and how the Havnes parameter
P can be used to support or negate the possibility of collective behavior of the dusty
plasma.

The result of applying these tools to the Jovian dust streams reveals mostly
dust-in-plasma behavior. In the orbits displaying the highest dust stream
fluxes, portions of orbits E4, G7, G8, C21 satisfy the minimum requirements for
a dusty plasma. However, the P parameter demonstrates that these mild dusty
plasma conditions do not lead to collective behavior of the dust stream
particles.

\\ ( http://arXiv.org/abs/astro-ph/0605539 , 97kb)

[The Messenger]

This is amazing...a planetary system behaving like a Mass Spectrometer...perhaps even a GCMS...