Session G1: APS1: Astronomy and Space Physics

Use of a magnetohydrodynamic model to investigate the viscous potential in Earth's magnetosphere

The solar wind flowing out from the Sun interacts with the Earth in a number of ways. While the most effective method of energy transfer occurs due to magnetic field merging, the mechanical viscous interaction between the solar wind and the Earth's magnetic field is a significant, though less well- understood mechanism. Using the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic (MHD) computer simulation, we have modeled a variety of solar wind conditions which are not readily available for study from satellite data. We then analyzed the simulation results to observe the relationships between solar wind density and velocity values versus the resultant viscous potential, projected onto the Earth's polar caps. Our analysis results are also compared to recent empirical model predictions for those same solar wind inputs.   

DyFK simulation of high plasma densities observed by Akebono during the June, 1989 geomagnetic storm

During the magnetic storm from 6 June to 10 June 1989, the plasma wave and sounder (PWS) experiments onboard Akebono spacecraft observed electron densities of 200-800 per c.c. around 10,000 km altitude, which are at least one order of magnitude higher than the electron densities during the geomagnetic quiet time. Using the UT Arlington Dynamic Fluid-Kinetic (DyFK) model, we simulated the energization and transport of O$^{+}$ and H$^{+}$ ions in the high-latitude region under geomagnetic storm conditions. The simulation results show that under strong soft electron precipitation and perpendicular wave heating, the ion densities and fluxes over the polar cap region are highly enhanced, which are in general consistent with the Akebono PWS observations.   

Ion Characteristics in Jupiter's Magnetotail from New Horizon data

Jupiter's gigantic magnetotail, extending 2500 Jovian radii, is the largest cohesive structure in our solar system. For the first time, NASA's New Horizons (NH) satellite in 2007 traversed almost axially. Data from its onboard SWAP instrument (Solar Wind Around Pluto), which makes coincidence measurements of the ions shows many periodic structures and existence of light and heavy ion species with varying densities in Jupiter's magnetotail plasma population. A better understanding of the physical processes governing such diversity requires knowing the characteristics of the various charged particles present, such as the ion density, velocity, temperature, and pressure. We have developed a 3-dimensional phase-space distribution model by constructing the observed signatures along with the calibration parameters provided by the SWAP team during the NH magnetotail flyby. The model uses five input parameters from SWAP. A 3-D isotropic Maxwellian distribution function is used to estimate density, velocity, and temperature, which is then converted into counts as the instrument measures the count rates. Finally, minimizing the chi-square fitting of our model results in the maximum likelihood of the various parameters. We will show our results from 500-800 RJ.   

Alfven Waves and Electron Energization and Their Interaction with Auroral Ionospheric Plasma Transport

When inertial Alfv\'en waves propagate along auroral field lines, they involve parallel electric fields that can accelerate auroral electrons. Here, we simulate the propagation of Alfv\'en waves through O+ and H+ auroral ionosphere-magnetosphere density profiles obtained from the UT Arlington Dynamic Fluid- Kinetic (DyFK) ionospheric plasma transport model [e.g; Estep et al; 1999]. A linear one dimensional gyrofluid code [Jones and Parker, 2003] is used for the Alfv\'en wave description, incorporating electron inertia, electron pressure gradient and finite ion gyroradius effects. Then, the test particle approach of Su et al. [2004] is used to simulate the response of a distribution of electrons to these Alfv\'en wave electric fields. These electrons are incorporated into the DyFK model to produce a partially-self-consistent approach to producing the associated ionization and thermal electron heating within the ionosphere-magnetosphere system.   

Langmuir Probe measurement and the Spacebuoy mission

Disturbances in the earth's magnetosphere and ionosphere can have profound impacts on earth and space-borne systems. The goal of the Spacebuoy mission at Montana State University is to contribute essential data to the GAIM (Global Assimilation of Ionospheric Measurements) model that is used by the Air Force Weather Agency to better understand the ionosphere. The Spacebuoy satellite will collect in-situ ion density and columnar total electron content (TEC) measurements and will demonstrate the feasibility of a buoy-like operations concept. The theory of Langmuir probe measurement in the ionosphere is presented, and particular considerations relevant to the Spacebuoy mission are discussed in detail.   

The Effects of Solar Wind Dynamic Pressure on the Coupling of Energy between the Solar Wind and Magnetosphere

Space physics seeks to understand the solar wind conditions which determine the interactions between the magnetosphere to the solar wind. In this pursuit, we are considering the effects of the changes in the solar wind dynamic pressure on the coupling between the solar wind electric field and the ring current injection rate (RCIR). The RCIR indicates the scale of the magnetosphere's response to the solar wind, with large values indicating greater changes and energy flow. The solar wind electric field provides a proxy for the amount of energy transferred into the magnetosphere. The boundary between the solar wind and the magnetosphere is created through a balance of the solar wind dynamic pressure with the magnetic pressure of the Earth. It is expected that modifications of this boundary through changes in the solar wind dynamic pressure will result in modifications in the RCIR response to the solar wind electric field. Through statistical analysis of satellite and ground-based data from 1995 to 2004, we examine the effects of dynamic pressure changes on the coupling of the solar wind electric field and RCIR.   

Telescope Control System Upgrade

Around 2002, it was decided at Texas A{\&}M University Kingsville to enhance the control system for the 16'' Newtonian / Cassegrain telescope located atop Hill Hall, the physics building on campus. A modern, state of the art control system was selected and purchased but even after two years, no progress had been made on the implementation and the telescope remained nonfunctioning and completely unusable. The author of this paper was asked to come in as an alumni volunteer and complete the implementation at minimal additional expense and return the telescope to operational condition. Various problems in design had to be identified and overcome and volunteers with other skill sets had to be attracted to the project in order to succeed. Over a period of several months, the new telescope control system hardware was installed on the telescope and the computer based control system was brought up to operational status.   

Origin of Planck's Constant in Galilean Relativity

In recent papers [1,2] the authors demonstrated that scalar waves in Galilean relativity must satisfy a unique Schr\"{o}dinger-like equation characterized by a ``mass-like'' parameter M, but not including Planck's constant as found in Schr\"{o}dinger's original equation. In this paper we show that a constant like Planck's constant is needed for a Newtonian observer to relate the wave parameter M to the classical mass M$_{C}$, a quantity which he can measure conveniently. This process also relates a classical potential to an interaction term in the Galilean wave equation and reveals the need for a constant like Planck's constant. We point out that Planck's constant is not unique in Galilean relativity and suggest that for certain potentials or elementary particles other values could occur. Consequences of the existence of other values of Planck's constant are discussed, and an unusual idea based on this possibility is presented as a possible explanation of dark matter. References: [1] Z.E. Musielak and J.L. Fry, Ann. Phys. 324 (2009) 296; [2] Z.E. Musielak and J.L. Fry, Int. J. Theor. Phys., in press (2009) DOI: 10.1007/s10773-008-9893-9.   

Characterizing Periodic Magnetospheric Behavior Through MHD Modeling

While studying periodic substorms, we found magnetospheric oscillations that share some characteristics with periodic substorms in the Lyon-Fedder-Mobary (LFM) global magnetospheric simulation. These events were found under steady solar wind driving, so the oscillations did not arise directly from period behavior in the solar wind. This study attempts to characterize the oscillations using the solar wind inputs and the inputs to the LFM ionospheric model. We will look at the effects on the oscillations from solar wind particle density, magnetic field, and velocity and the ionospheric conductivity from the perspective of periodic substorms.   

A Tale of Two Variable Stars

During a year-long program of CCD photometric monitoring of eighty five Cepheid variable (pulsating) stars searching for period changes associated with their stellar evolution, a serendipitous discovery of a new, bright eclipsing binary star-- the early-type, high luminosity emission line star BD+48 1098--was made in the same field as that of the well known pulsating star BM Persei.   

Thermal History of the Early Universe

The universe is considered to be extremely hot and dense in the beginning. The expansion of the universe started right from the beginning. We study the particle production with the age of the early universe and the corresponding change in temperature. The particle properties are also studied at different temperatures.   

Rapid Response for Observational Astronomical Transient Events and Monitoring

There is a need for Rapid Confirmation of Transient Events that smaller research grade university observatories can fulfill. These include: 1) Asteroid and Comet Discovery Confirmation; 2) Data Collection for Orbital Predictions; 3) Initial Nova and Super Nova Light Curves. In addition to the availability of a telescope, the faculty and undergraduate students can provide the manpower and expertise to conduct long term observational data for: 1) Long Term Monitoring for Determination of Orbital Elements of Asteroids and Comets; 2) Extra Solar Planetary Confirmation and Long Term Data Collection. Tarleton State University is meeting these needs through:1) Research Grade 32-inch Telescope; 2) Availability of telescope for Rapid Response; 3) Faculty and Undergraduate Time for Observations and Data Collection; 4) 2400 X 2400 CCD Camera and filters and 5) High Percentages of Clear Skies, Mid Latitude and Central Time Zone