Atmospheres of Outer Planet Satellites

1976 ◽  
pp. 85-112
Keyword(s):  
Outer Planet

scholarly journals Elastic Electron Scattering from Methane Molecule in the Energy Range from 50–300 eV

2021 ◽  
Vol 22 (2) ◽  
pp. 647
Author(s):  
Jelena Vukalović ◽  
Jelena B. Maljković ◽  
Karoly Tökési ◽  
Branko Predojević ◽  
Bratislav P. Marinković
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Electron Gun ◽  
Methane Molecule ◽  
Edge Plasma ◽  
Electron Interaction ◽  
Outer Planet ◽  
Elastic Electron

Electron interaction with methane molecule and accurate determination of its elastic cross-section is a demanding task for both experimental and theoretical standpoints and relevant for our better understanding of the processes in Earth’s and Solar outer planet atmospheres, the greenhouse effect or in plasma physics applications like vapor deposition, complex plasma-wall interactions and edge plasma regions of Tokamak. Methane can serve as a test molecule for advancing novel electron-molecule collision theories. We present a combined experimental and theoretical study of the elastic electron differential cross-section from methane molecule, as well as integral and momentum transfer cross-sections in the intermediate energy range (50–300 eV). The experimental setup, based on a crossed beam technique, comprising of an electron gun, a single capillary gas needle and detection system with a channeltron is used in the measurements. The absolute values for cross-sections are obtained by relative-flow method, using argon as a reference. Theoretical results are acquired using two approximations: simple sum of individual atomic cross-sections and the other with molecular effect taken into the account.

scholarly journals Variability in the outer planet aurorae

1992 ◽  
Vol 12 (8) ◽  
pp. 137-148
Author(s):  
John T. Clarke
Keyword(s):  
Outer Planet

Toward constraining Saturn's rotation rate by interior modeling

2021 ◽  
Author(s):  
Nadine Nettelmann ◽  
Jonathan J. Fortney
Keyword(s):  
Broad Spectrum ◽  
Rotation Rate ◽  
Rotation Period ◽  
Outer Planet ◽  
Fall Meeting ◽  
Density Profiles ◽  
A Value ◽  
Periodic Signals ◽  
Under Construction ◽  
Even Harmonics

<p>The rotation rate of the outer planet Saturn is not well constrained by classical measurements of periodic signals [1]. Recent and diverse approaches using a broad spectrum of Cassini and other observational data related to shape, winds, and oscillations are converging toward a value about 6 to 7 minutes faster than the Voyager rotation period.<br>Here we present our method of using zonal wind data and the even harmonics J<sub>2</sub> to J<sub>10</sub> measured during the Cassini Grand Finale tour [2] to infer the deep rotation rate of Saturn. We assume differential rotation on cylinders and generate adiabatic density profiles that match the low-order J<sub>2</sub> and J<sub>4</sub><br>values. Theory of Figures to 7th order is applied to estimate the differences in the high-order moments J<sub>6 </sub>to J<sub>10</sub> that may result from the winds and the assumed reference rotation rate. Presented results are preliminary as the method is under construction [3].</p><p>[1] Fortney, Helled, Nettelmann et al, in: 'Saturn in the 21st century', Cambridge U Press (2018)<br>[2] Iess, Militzer, Kaspi, Science 364:2965 (2019)<br>[3] Nettelmann, AGU Fall Meeting, P066-0007 (2020)</p><p> </p>

scholarly journals Retrograde resonances in compact multi-planetary systems: a feasible stabilizing mechanism

2007 ◽  
Vol 3 (S249) ◽  
pp. 511-516 ◽  
Author(s):  
Julie Gayon ◽  
Eric Bois
Keyword(s):  
Body Problem ◽  
Extrasolar Planets ◽  
Planetary Systems ◽  
Central Star ◽  
Point Of View ◽  
Outer Planet ◽  
Mean Motion Resonances ◽  
Hot Jupiters ◽  
The Stability ◽  
Orbital Data

AbstractMulti-planet systems detected until now are in most cases characterized by hot-Jupiters close to their central star as well as high eccentricities. As a consequence, from a dynamical point of view, compact multi-planetary systems form a variety of the general N-body problem (with N ≥ 3), whose solutions are not necessarily known. Extrasolar planets are up to now found in prograde (i.e. direct) orbital motions about their host star and often in mean-motion resonances (MMR). In the present paper, we investigate a theoretical alternative suitable for the stability of compact multi-planetary systems. When the outer planet moves on a retrograde orbit in MMR with respect to the inner planet, we find that the so-called retrograde resonances present fine and characteristic structures particularly relevant for dynamical stability. We show that retrograde resonances and their resources open a family of stabilizing mechanisms involving specific behaviors of apsidal precessions. We also point up that for particular orbital data, retrograde MMRs may provide more robust stability compared to the corresponding prograde MMRs.

scholarly journals Cassini/Huygens Mission To Saturn: Results And Prospects

2005 ◽  
Vol 13 ◽  
pp. 904-904
Author(s):  
Dennis L. Matson ◽  
Jean-Pierre Lebreton ◽  
Linda Spilker
Keyword(s):  
Magnetic Field ◽  
Current Status ◽  
Outer Planet ◽  
Simultaneous Measurements ◽  
The Earth ◽  
Bilateral Agreement ◽  
Interplanetary Trajectory ◽  
Jovian System ◽  
Intensive Observations ◽  
Scientific Results

The Cassini spacecraft was launched in October, 1997. Since then it has been on an interplanetary trajectory aimed toward Saturn and arriving there on July 1, 2004. En route, Cassini has flown by Venus, the Earth, and Jupiter. Each of these events yielded new scientific results, (e.g., 11 papers in J. Geophys. Res. 106, 30099-30279.) The Cassini flyby of Jupiter, with Galileo already in Jovian orbit, enabled the first-ever simultaneous measurements by two spacecraft at an outer planet. This fortuitous event provided a unique opportunity to investigate the giant planet’s magnetic field and the properties of the Jovian system. It provided a focused period for intensive observations of Jupiter and cooperation with investigators using Galileo, Hubble, Chandra, and ground-based observatories. The results achieved at Jupiter were stunning (e.g., 8 articles in Nature 415, 965-1005, February 28, 2002). Recent results and the current status of the spacecraft and mission will be discussed. Of note are the dates of July 1, 2004 when Cassini goes into orbit about Saturn and January 14, 2005 when Huygens enters the atmosphere of Titan. The Cassini/Huygens mission is a joint undertaking by NASA and ESA, with ASI as a partner via a bilateral agreement with NASA.

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