Astrophysics and Astronomy Commons^™

Stability Of Phyllosilicates On Mars, Patricia Gavin

Graduate Theses and Dissertations

This study investigates the stability of phyllosilicates on the surface of Mars through laboratory experiments and analysis of terrestrial analogs. Phyllosilicates are mostly found in the oldest Noachian terrains on Mars and hence hold clues to the planet's earliest aqueous and geologic history. Phyllosilicates relevant to Mars were heated up to ~1100°C for up to 24 hours and impacted with projectile velocities up to ~4.5 km/s. Heated samples were analyzed using x-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy in the near- (NIR, 1.0-2.5 µm) and mid-infrared (MIR, 5.0-15.0 µm) ranges. Impacted samples were also analyzed using Raman spectroscopy …

Subsurface Planetary Investigation Techniques And Their Role For Assessing Subsurface Planetary Composition, Ahmed Elshafie

Graduate Theses and Dissertations

Subsurface planetary investigation techniques are of high interest and importance for the scientific community. Not only they can enhance our knowledge of the history of planetary formation but also can lead to information about its future. Whether the investigation is being conducted remotely using imagers, radars or physically using penetrometers or drills, a pre-existed knowledge of the mechanical and electrical properties of the subsurface regolith should be acquired for better data interpretation and analysis. Therefore, the main objective of this work is to investigate the mechanical and electrical properties of planetary analogs, understand their role for assessing the subsurface structure …

Orbital Periodicities Reflected In Ancient Surfaces Of Our Solar System And The Implications For A Record Of Early Life, Dixie Lee Androes

Graduate Theses and Dissertations

Uniformitarian processes, governed by invariant physical laws, remain the most reliable source for reconstructing the past. Driving many of the repetitive, predictable processes are the orbital dynamics of the Sun-Planet-Moon systems. Astronomical periodicities range from a few hours (tides) to thousands of years (Milankovitch). These periodicities, combined with geomorphic observations of planetary surfaces, constrain the time-dependent processes and allow for reconstruction of events and conditions favorable for sedimentary accumulations. This research suggests that seasonal sedimentary processes are dominant on Titan and Mars, and have played a significant role in the formation of ancient banded-iron formations (BIF's) on Earth.

Earth, Mars, …

Exploring The Possibility Of Floating Orbits For Extreme Mass Ratio Binary Black Holes, Shasvath Jagat Kapadia

Graduate Theses and Dissertations

A binary black hole system, where each black hole orbits the system's center of mass, loses energy by emission of gravitational waves. This causes both black holes to spiral in towards each other. However, if the binary were to, by some mechanism, gain orbital energy at the same rate that it radiates away this energy, a non-decaying or “floating” orbit would result. The thesis uses superradiant scattering and tidal friction, which are two equivalent ways of looking at a process by which the system can gain orbital energy from the spin energy of either black hole, to determine the possibility …

Modeling Water Stability And Transport On Mars And Iapetus: Exploring Their Effects On Geomorphic And Atmospheric Processes, Edgard Giovanni Rivera-Valentin

Graduate Theses and Dissertations

The stability and transport of water on solid planetary surfaces strongly affects both atmospheric and surfaces processes. In this work, two bodies are specifically investigated where transport of water is relevant: Iapetus and Mars. Iapetus, an icy Kronian satellite, has a drastic albedo contrast on its surface and one of the darkest surfaces in the solar system. This extreme brightness contrast is suggested to occur via the transport of water ice from the leading hemisphere to the trailing hemisphere and the poles. Here a global heat and mass transfer model is developed for Iapetus in order to study the current …

Experimental Simulations Of Dark Slope Streaks On Mars, Kelly Howe

Graduate Theses and Dissertations

Martian slope streaks were first observed in Viking images but their formation still remains ambiguous. Martian slope streaks are currently occurring geological phenomenon on Mars, which requires any formation theory to be in agreement with Mar's current temperature and pressure conditions. Planar morphology of martian slope streaks suggest a potential fluvial formation, but current conditions on Mars are not conducive to water remaining liquid long enough to erode the surface. Debris flows, fluid stains and dry dust avalanches have all been previously cited as a potential formation mechanism for martian slope streaks. Recent experimental simulations indicate that a fluvial source …

Interacting Dark Energy Models And The Cosmic Coincidence Problem, H. Shojaei, C. Smith, D. Waters

Journal of the Arkansas Academy of Science

Interacting dark energy models have been employed to study the behavior of dark energy and matter in the presence of an interaction between the two. One of the successful aspects of these models is how they explain the cosmic coincidence problem. In this work we consider a specific interaction to study the behavior of dark energy and matter through the history of evolution.

Profiles In Science: Stephen Hawking, Kathleen A. Lehman

University Libraries Faculty Publications and Presentations

While Stephen Hawking’s early academic career lacked focus, the development of motor neuron disease straining against his hopes for a fulfilling life pulled the young scientist’s work together. He has since become the world’s most famous scientist due, in part, to his strong belief that science should be accessible to the general public. Hawking has published frequently for the academic community but has also published for the lay reader. His life has been recorded and examined by several biographers. This paper gives an overview of Hawking’s early life, academic career, his academic and popular publications, as well as a few …

Flux Variation Of Cosmic Muons, N. Ramesh, M. Hawron, C. Martin, A. Bachri

Journal of the Arkansas Academy of Science

In the current paper, we analyzed the variation of cosmic radiation flux with elevation, time of the year and ambient temperature with the help of a portable cosmic muon detector, the construction of which was completed by a team from Southern Arkansas University (SAU) at Lawrence Berkeley National Laboratory (LBNL). Cosmic muons and gamma rays traverse two synchronized scintillators connected to two photomultiplier tubes (PMT) via light guides, and generate electronic pulses which we counted using a Data Acquisition Board (DAQ). Because muons are the product of collisions between high-energy cosmic rays and atmospheric nuclei, and therefore shower onto earth, …

New Eclipsing Close Binary Star In The Constellation Of Sextants, Jeff W. Robertson

Journal of the Arkansas Academy of Science

No abstract provided.

A Timer Module For An 8051 Microcontroller, Troy England

Electrical Engineering Undergraduate Honors Theses

A timer module for an 8051 Microcontroller is designed from the ground up. It could potentially be integrated into a larger 8051 for use in lunar and Martian missions. It follows through a synchronous digital design flow from HDL code through layout verification. The timer shows functionality at 100MHz with some minor glitches.

Taking Another Look: Light N-Capture Element Abundances In Metal-Poor Halo Stars, D. Burris, E. Jones, J. Lusk

Journal of the Arkansas Academy of Science

Elements are produced in stars through a variety of processes; some are well known, others are still the object of active research. The elements Zirconium (Zr) and Yttrium (Y) are produced via neutron capture (ncapture). These elements reside in the mass range where there is uncertainty about the production mechanism at early time. The rapid n-capture process (r-process) was believed to be responsible for the production, but no study (Burris et al 2000, Gilroy et al 1988 and others) has been able to successfully use the r-process to reproduce the abundance signature for elements in this mass range for metal-poor …

Variational Symmetries And Conservation Laws In Linearized Gravity, Balraj Menon

Journal of the Arkansas Academy of Science

The methods of symmetry group analysis are applied to the action functional of linearized gravity to derive necessary conditions for the existence of variational symmetries. Two classes of variational symmetries of linearized gravity are discussed, and the local conservation laws associated with these variational symmetries are presented by applying Noether's theorem

New Pulsating Variable Discovered In The Constellation Andromeda, Jeff W. Robertson

Journal of the Arkansas Academy of Science

No abstract provided.

Be Star Spectroscopy Using The Uca Fiber-Fed Spectrograph, Scott Austin

Journal of the Arkansas Academy of Science

Beginning in June 2003, undergraduate students and the author have spectroscopically monitored bright Be stars using a custom built fiber-fed spectrograph attached to the UCA Observatory 11-inch Schmidt-Cassegrain telescope. We have obtained 0.8 Angstrom/pixel resolution spectra of the H-alpha line for over forty Be-Stars. Some have been observed on multiple dates in order to detect any temporal changes. Line profiles, velocities, and observed variations for some of these stars will be presented.

Stimulation And Modeling Of Pond Formations On The Asteroid 433 Eros, Justin Thompson

Inquiry: The University of Arkansas Undergraduate Research Journal

"Ponds" are surface features that appear to be the result of the deposition of finer material on the asteroid's regolith, the layer of loose sediment that blankets the entire asteroid. Ponds were discovered by the NEAR Shoemaker spacecraft in January, 2001, on the asteroid 433 Eros. The objective of experimentation is to simulate the development of these ponds in the Andromeda planetary sciences environmental chamber. The Andromeda Chamber offers a unique ability to simulate surface environments that occur on Eros. The chamber was used to simulate the processes that occur as Eros emits gas through its outer surface, including the …

Multi-Phase Transport Study Of Relativistic Nuclear Collisions, Bin Zhang, C. M. Ko, Bao-An Li, Ziwei Lin, Subrata Pal

Journal of the Arkansas Academy of Science

A multi-phase transport model (AMPT) is developed for the study of hot and dense matter produced in relativistic nuclear collisions. This model includes both initial partonic and final hadronic scattering. Using the AMPT model, we study the momentum distributions of charged particles such as protons, antiprotons, pions, and kaons in central heavy ion collisions at Super Proton Synchrotron (SPS) and Relativistic Heavy Ion Collider (RHIC) energies. The results are consistent with experimental data at these energies. They indicate a significant nuclear shadowing but a relative weak jet quenching in the initial dense matter. Antiproton to proton ratio at mid-rapidity increases …

Estimating Milky-Way Dark Matter: Its Amount And Distribution, Jeffery E. Clayton, Sue Ellen Mccloskey, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

No abstract provided.

Creation And Implementation Of A Tracking Module For A Small-Geometry, Vertex Time Projection Chamber, Christine A. Byrd, Wilson H. Howe, Amber D. Climer, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

A charged-particle tracking module was written and tested using pixel data generated from CERN's Monte Carlo detector-modeling program GEANT. This tracking module was customized for testing the design of a micro-strip gas time project chamber, designed by Drs. Margetis and Wieman of the Relativistic Nuclear Collisions Group at Lawrence Berkeley Laboratory. This low-mass, high-resolution, small-geometry vertex time projection chamber was designed for possible use with a larger instrument in an experiment using the relativistic heavy ion collider, RHIC, under construction at Brookhaven National Laboratory in New York. Implementing this tracking module involved generating tables and source code in a manner …

Using Geant To Model Calrimeter Response For Electromagnetic Cascades From Nucleus-Nucleus Interactions In A Cosmic Ray Detector, Kazuhiko Murai, Carlos A. Sanchez, Donald C. Wold

Journal of the Arkansas Academy of Science

Ascintillating optical fiber calorimeter (SOFCAL) is being developed by NASA/Marshall Space Flight Center for use in balloon-borne experiments to study the spectrum of high-energy cosmic rays and gamma rays. SOFCAL will not saturate for long exposures and the calorimeter willbe useful in emulsion chambers to study primary cosmic-ray nuclei with energies from 100 GeV to 1,000 TeV. The event generator FRITIOF was used to model the collision of a cosmic-ray projectile with a target nucleus inan emulsion chamber. The measurements of charged particles from the interaction in the emulsions are related to the energy of the primary cosmic ray nucleus-nucleus …

Using Fritiof To Model Nucleus-Nucleus Interactions In A Cosmic Ray Detector, Carlos A. Sanchez, Kazuhiko Murai, Donald C. Wold

Journal of the Arkansas Academy of Science

Ascintillating optical fiber calorimeter (SOFCAL) isbeing developed by NASA/Marshall Space Flight Center for use in experiments to study the spectrum of high-energy cosmic rays and gamma rays from 100 GeV to 1,000 TeV. SOFCAL willnot saturate for long exposures and this calorimeter inthese balloon-borne emulsion chambers willbe helpful for the study of the composition of primary cosmic-ray nuclei. For primary nuclei with energies much greater than 1014 eV, nucleus-nucleus interactions are likely to exhibit characteristics of a quark-gluon plasma (QGP). Aparticle event generator was used tomodel the collision of a cosmic-ray nucleus with a target nucleus inan emulsion chamber. FRITIOF …

Monte Carlo Simulation Of The Scintillating Optical Fiber Calorimeter (Sofcal), Zibin Yang, Russell Gillum, Donald C. Wold

Journal of the Arkansas Academy of Science

A scintillating optical fiber calorimeter (SOFCAL) is being developed by NASA/Marshall Space Flight Center for use in balloon-borne emulsion chambers to study the spectrum of high-energy cosmic rays and gamma rays. SOFCAL will not saturate for long exposures, and the detector will be helpful for the study of primary cosmic-ray nuclei energies from 100 GeV to 1,000 TeV. For a given incident particle and energy, computer simulations of electromagnetic cascades allow computation of energy deposited in different regions of the calorimeter. For these initial simulations, a 5-cm x 5-cm x 7-cm calorimeter was used. Each subsection contained a 0.4-cm thick …

Time Projection Chamber's Efficiency, Obtained Using Cern's Geant Code, Christine A. Byrd, Charles M. Byrd, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

Geometrical acceptance and reconstruction of tracks have been carried out for a Time Projection Chamber (TPC) used in Experiment NA35: the 35th experiment in the North Area of the Super Proton Synchrotron (SPS), located at the European Organization for Nuclear Research (CERN). NA35 used the SPS at CERN to produce 6.4 TeV beams of 32S for central collisions with Au nuclei. The TPC modeling effort used a modified version of CERN's Monte Carlo program GEANT, which simulates the response of the NA35 TPC to output from CERN's primary event generators. GEANT was used to simulate three-dimensional pixel data in the …

Monte Carlo Director Modeling And Display, Using The Cern Laboratory, Christine A. Byrd, Charles M. Byrd, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

Detectors for high energy nuclear physics experiments are being modeled using programs developed and maintained at CERN, the European Organization for Nuclear Research. These programs include data handling and display routines, as well as those using random-sampling Monte Carlo techniques to calculate energy depositions for high energy particles as they pass through the various parts of the detector system. The complete CERN library has been imported for use with our Workstation computers in a multiple user environment. The enormous CERN Monte Carlo program GEANT(French for GIANT) tracks the progress of a particle through a detector on a simulated event-by-event basis. …

Pole Stars Of Other Planets, Paul C. Sharrah

Journal of the Arkansas Academy of Science

The north celestial pole of the Earth and the other planets is discussed. Right ascension and declination information on the location of the poles on the celestial sphere is summarized. The name of the brightest visible star near each pole is given and the special case of Uranus is discussed.

Twenty Years Of Experience With The University Of Arkansas Planetarium, Paul C. Sharrah

Journal of the Arkansas Academy of Science

The Model A-1 Spitz planetarium was placed in operation at the University of Arkansas in 1954. It was moved to its present location in 1972 and has continued to have a much expanded use. More than 8,000 persons attended demonstrations between 1 August 1972 and 31 March 1974. Approximately one third of these were University students in classes and laboratories; the remaining two thirds were accounted for by school and other youth groups and the public demonstrations.