Bulletin of the American Physical Society
Joint Fall 2009 Meeting of the Texas Sections of the APS, AAPT, and SPS
Volume 54, Number 13
Thursday–Saturday, October 22–24, 2009; San Marcos, Texas
Session G2: Astronomy and Astrophysics II |
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Chair: Lorenzo Brancaleon, University of Texas at San Antonio Room: LBJ Student Center 3-14.1 |
Saturday, October 24, 2009 10:00AM - 10:12AM |
G2.00001: A Computer Based Synthetic Telluric Line Atlas Charles Allison Earth's atmosphere provides a substantial blanket of gases surrounding our planet that has a definite effect upon the spectrum and intensity of incoming light from astronomical objects. The effect is molecular absorption lines imposed upon the incoming signal which are referred to as telluric lines. While space based instruments such as the Hubble are placed well above Earth's atmosphere, there are far more telescopes and equipment in use which are located on Earth and are subject to the problems of telluric lines. This article describes the implementation of a computer-based, synthetic atlas for telluric lines based upon data from the HITRAN molecular database. This atlas differs from others created by direct measurement in that it permits custom tailoring of parameters to fit the specific needs of an observer. Uses include telluric line identification, wavelength calibration, filter selection analysis, and in some cases, photometric intensity correction. [Preview Abstract] |
Saturday, October 24, 2009 10:12AM - 10:24AM |
G2.00002: Correlation between propagated solar wind and the response of Jupiter's Magnetosphere observed by Galileo. Yanshi Huang, Kenneth Hansen, Yue Deng For the magnetosphere of Jupiter, the internal processes including rapid rotation, strong mass loading from Io, play major roles, however, solar wind driving is also important. We used a one-dimensional simulation of solar wind, with all variables as a function of the radius propagating from Earth out to Jupiter to compare with the measurements from Galileo Magnetometor(MAG). With the limitation in the heliographic longitude that we can model, the simulated solar wind represents the actual solar wind well along the Sun-Earth line, i.e., through those Sun-Earth-Jupiter oppositions. The correlation between changes of dynamic pressure in the solar wind and corresponding changes of magnetic field magnitude, orientation and lag angle observed by Galileo, will help us to understand the role of solar wind forcing on the magnetosphere system. The correlation result shows different responses at different locations in Jupiter's magnetosphere. [Preview Abstract] |
Saturday, October 24, 2009 10:24AM - 10:36AM |
G2.00003: Saturation of Transpolar Potential for Large Y-component Interplanetary Magnetic Field Elizabeth Mitchell, Ramon Lopez This study examines the response of the transpolar potential to a large Y-component interplanetary magnetic field ($B_y$). The transpolar potential responds nonlinearly, saturates, for large IMF in the LFM global MHD simulation. This response occurs for both large $B_y $ and large $B_z$. DMSP satellites data and AMIE results confirm the saturation of the transpolar potential during large $B_y$. The magnitude of the IMF at which the transpolar potential becomes nonlinear is the same for the large $B_y$ cases as for the large $B_z$ cases. The magnitude of the transpolar potential at which it becomes nonlinear is significantly smaller for the large $B_y$ cases than the large $B_z$ cases. This indicates transpolar potential saturation does not depend on the strength of the region 1 current. Rather, these results suggest region 1 current may be limited by the transpolar potential. [Preview Abstract] |
Saturday, October 24, 2009 10:36AM - 10:48AM |
G2.00004: Simulating the viscous interaction under a variety of solar wind conditions, with some comparisons to satellite data Robert Bruntz, Ramon Lopez, Micah Weberg, John Lyon, Michael Wiltberger The viscous interaction is a mode of energy transport between the solar wind and Earth's magnetosphere. Its effects are often difficult to isolate from other effects in in-situ measurements. Therefore, it can be useful to simulate the viscous interaction under a variety of solar wind conditions, especially since those conditions are often impossible to find in satellite data. We have used the Lyon-Fedder-Mobarry simulation to look at the viscous potential in Earth's ionosphere for a variety of solar wind velocities, densities, and magnetic field strengths. Where possible, we have compared those results to low and high altitude satellite measurements. [Preview Abstract] |
Saturday, October 24, 2009 10:48AM - 11:00AM |
G2.00005: Looking for polar cap potential saturation under strong northward Bz using DMSP satellite data Sophia Cockrell, Robert Allen, Shree Bhattarai, Ramon Lopez The ability to predict the effects of the solar wind on the near-Earth space environment is receiving attention due to the ever increasing use of satellites and aircraft by consumers and governments. The cross polar cap potential is one way of measuring interaction between the solar wind and Earth's magnetosphere. Recent simulations and ground based radar measurements have shown that the polar cap potential responds less and less to high values of northward interplanetary magnetic field (IMF), an effect known as saturation. To study this effect, we use data from a DMSP satellite, which flies at low altitude directly over Earth's polar caps. This data, gathered in situ, provides a more direct measurement of the polar cap potential. We will present an analysis of this data and compare it to simulation and radar results. [Preview Abstract] |
Saturday, October 24, 2009 11:00AM - 11:12AM |
G2.00006: Searching for evidence of convective cells within Earth's magnetotail Micah Weberg, Robert Bruntz, Ramon Lopez The solar wind flows continually out from the sun, carrying energy and momentum in its stream of plasma, and shaping the Earth's magnetosphere. The magnetosphere is defined as the region of space dominated by the Earth's magnetic field. Viscous interactions have been suggested as one of the ways momentum and energy can be transferred from the solar wind, across a boundary called the magnetopause, and into the magnetosphere. Current models indicate that this phenomenon should cause a cell of circulating plasma to form just inside the magnetopause. This flow pattern, sometimes likened to a convection cell, produces an electric potential which is transmitted along magnetic field lines into the ionosphere near the polar cap. Using data from the THEMIS satellites, we will explore the motion of plasma near the magnetopause within the magnetotail to look for evidence of these ``convective cells.'' We will compare some THEMIS observations to our expectations of convective cells and discuss some implications it may have for ionospheric physics. [Preview Abstract] |
Saturday, October 24, 2009 11:12AM - 11:24AM |
G2.00007: The Effect of Large B$_{y}$ on Currents in the Polar Cap Robert Allen, Sophia Cockrell, Ramon Lopez, Dustin Brewer, Elizabeth Mitchell In the polar cap, plasma flow is driven primarily by \textbf{E} x \textbf{B} drift. The two-cell convection pattern flows anti-sunward on the noon-midnight line and returns sunward on the equatorward edges of the polar cap. As the magnitude of the dawn-dusk interplanetary magnetic field (IMF B$_{y})$ grows, one of the cells enlarges as the other shrinks. During these times, we predict that a current will flow out of one pole, travel along the Earth's bow shock, and then into the other pole along open field lines. This current should create a small cell of convection entirely on open field lines. We have used the electron flux instruments and plasma drift meters on DMSP satellites to locate the open-closed field line boundaries and the convection reversal boundaries for comparison with each other. We will present statistics and cases showing how the polar current depends on IMF B$_{y}$. [Preview Abstract] |
Saturday, October 24, 2009 11:24AM - 11:36AM |
G2.00008: Plasma On the Rocks: DC Atmospheric-Pressure Normal Glow Plasma Enhanced by Natural Basalt Microdischarges Karl Stephan, Sagar Ghimire DC normal glow discharges at atmospheric pressure in air and other gases are of interest in plasma processing, since they eliminate the need for low-pressure technology and vacuum-compatible materials. We have found that a DC normal glow discharge in air is stabilized and enlarged by passing it through a thickness of low-porosity rock such as basalt or granite. We observe a stable positive column in air up to 15 mm long with stable striations that depend on current. The airborne portion of the discharge shows characteristics of a normal glow discharge, including relatively constant voltage as current varies. A 13-kV, 5 mA discharge between a tungsten electrode 30 mm away from the surface of a basalt sample enlarges to over 15 mm diameter at the surface. We will present still and motion photography, spectra, and I-V measurements of this phenomenon, along with a simplified theory. [Preview Abstract] |
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