44 research outputs found
Exact Solutions of Model Hamiltonian Problems with Effective Interactions
We demonstrate with soluble models how to employ the effective Hamiltonian
approach of Lee and Suzuki to obtain all the exact eigenvalues of the full
Hamiltonian. We propose a new iteration scheme to obtain the effective
Hamiltonian and demonstrate its convergence properties.Comment: 12 pages and 1 figur
Large-space shell-model calculations for light nuclei
An effective two-body interaction is constructed from a new Reid-like
potential for a large no-core space consisting of six major shells and is used
to generate the shell-model properties for light nuclei from =2 to 6. (For
practical reasons, the model space is partially truncated for =6.) Binding
energies and other physical observables are calculated and compare favorably
with experiment.Comment: prepared using LaTex, 21 manuscript pages, no figure
The Earth: Plasma Sources, Losses, and Transport Processes
This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed
Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra
The annual and longitudinal variations in plasmaspheric ion density
This paper shows that at solar maximum, equatorial ion densities at L = 2.5 are substantially higher at American longitudes in the December months than in the June months. This arises because the configuration of the geomagnetic field causes a longitude-dependent asymmetry in ionospheric solar illumination at conjugate points that is greatest at American longitudes. For example, at â60°E geographic longitude the L = 2.5 field line has its foot point near 65° geographic latitude in the Southern Hemisphere but near 42° latitude in the Northern Hemisphere. We investigated the consequent effects on equatorial electron and ion densities by comparing ground-based observations of ULF field line eigenoscillations with in situ measurements of electron densities (from the CRRES and IMAGE spacecraft) and He+ densities (IMAGE) for L = 2.5 at solar maximum. Near â60°E longitude the electron and ion mass densities are about 1.5 and 2.2 times larger, respectively, in the December months than in the June months. Over the Asia-Pacific region there is little difference between summer and winter densities. Plasmaspheric empirical density models should be modified accordingly. By comparing the electron, helium, and mass densities, we estimate the annual variation in H+, He+, and O+ concentrations near â3°E longitude and â74°E longitude. In each case the He+ concentration is about 5% by number, but O+ concentrations are substantially higher at â3°E longitude compared with â74° E. We speculate that this may be related to enhanced ionospheric temperatures associated with the South Atlantic anomaly
Mass and electron densities in the inner magnetosphere during a prolonged disturbed interval
The equatorial plasma density and composition at L = 2.5 were studied during an extended disturbed interval using field line resonance measurements (yielding plasma mass density), naturally and artificially stimulated VLF whistlers (electron number density) and IMAGE EUV observations (plasmapause position and line-of-sight He+ intensity). During the storm the plasmapause moved to L < 2.5 and at least one density notch and drainage plume formed. These features were evident in all the data sets for some days. One notch extended from 2.4â4.5 R E and spanned <4 hours in MLT. Plume mass and electron densities were enhanced by a factor of about 3. In the plasmasphere and plasmatrough the H+: He+: O+ composition by number was âŒ82:15:3. However, just outside the plasmapause the O+ concentration exceeded 50%, suggesting the presence of an oxygen torus
Corrigendum to âSaturn in Lyman α: A comparison of Cassini and Voyager observationsâ [Icarus 339 (2020) 113594]
International audienc
Corrigendum to âSaturn in Lyman α: A comparison of Cassini and Voyager observationsâ [Icarus 339 (2020) 113594]
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The Breathing Plasmasphere: Erosion and Refilling
Global observations of He+ ions from the Imager for Magnetopause-to-Aurora Global Exploration mission Extreme Ultraviolet Imager are used to examine the dynamics of plasmasphere content using integrated mass through times of erosion and refilling for (Formula presented.). Perhaps the most basic and important attributes of the plasmasphere are its mass and spatial distribution. However, our understanding is often constrained by the method of measurement. Storm-time loss of plasmasphere content is a kind of exhalation where plasma is lost. Refilling or inhalation into the body of the plasmasphere occurs during the following calm. Using a follow-the-mass approach, storm-time plasmasphere loss for (Formula presented.) is found to range from 32% to 62% during three events. Plasma lost inside the average eroded plasmapause boundary ranges from 22% to 42% and outside from 35% to 72%. Following the start of refilling, the innermost L-shells show the lowest observed refilling rates. Mass refilling rates at higher L-shells rise to a maximum observed âŒ6 Mt/day near L = 4.5 that is less at higher L-shells (Mt/d = 1,000 kg/day). More variability and higher refilling rates are found during lower solar activity. The mass content of the plasmasphere between L = 1.5 and 3.0 was also followed for 54 days when it exhibited eight âbreathes.â Using this analogy, only the first inhale/exhale is âdeep.â The remaining carry forward the consequences of past and continued activity that prevents full recovery. There appears to be a month-long declining trend in the mass of the inner plasmasphere during the last two thirds of this time. © 2021. American Geophysical Union. All Rights Reserved. This article has been contributed to by US Government employees and their work is in the public domain in the USA.Public domain articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]