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Chandra Spectral Constraints Of The Low-Metallicity Collision Ring Cartwheel Galaxy, Chloë Benton 2022 University of Arkansas, Fayetteville

Chandra Spectral Constraints Of The Low-Metallicity Collision Ring Cartwheel Galaxy, Chloë Benton

Physics Undergraduate Honors Theses

With the sophistication of the Chandra X-Ray Observatory, many observations of the behaviors of binary systems have been researched and studied. As an excellent example, for the low metallicity Cartwheel Galaxy, some fraction of the X-ray photons emitted from X-ray binaries have been intercepted by the detectors on the telescope and have been compiled into “events file.” When modeled properly, this data can produce insight into the behavior of the stellar populations in this object. The primary goal of this project is to use these events files to measure the X-ray properties of the X-ray binaries in the Cartwheel Galaxy ...


Mms Observations Of The Kelvin-Helmholtz Instability And Associated Ion Scale Waves, Rachel C. Rice 2022 Embry-Riddle Aeronautical University

Mms Observations Of The Kelvin-Helmholtz Instability And Associated Ion Scale Waves, Rachel C. Rice

PhD Dissertations and Master's Theses

The detailed mechanisms coupling the solar wind to Earth's magnetosphere are not yet fully understood. Solar wind plasma is heated non-adiabatically as it penetrates the magnetosphere, and this process must span scale sizes. Reconnection alone is not able to account for the observed heating; other mechanisms must be at work. One potential process is the Kelvin-Helmholtz instability (KHI). The KHI is a convective instability which operates at the fluid scale in plasmas, but is capable of driving secondary process at smaller scales. Previous work has shown evidence of magnetic reconnection, various ion scale wave modes, mode conversion, and turbulence ...


The Spectra Of Hydrogen-Deficient Carbon Stars: The Effects Of Evolution And Nucleosynthesis, Courtney Lauren Crawford 2022 Louisiana State University and Agricultural and Mechanical College

The Spectra Of Hydrogen-Deficient Carbon Stars: The Effects Of Evolution And Nucleosynthesis, Courtney Lauren Crawford

LSU Doctoral Dissertations

The rare class of stars known as the Hydrogen-deficient Carbon (HdC) stars includes the R Coronae Borealis (RCB) variables and the non-variable Dustless HdC (dLHdC) stars. These stars are believed to be formed via the merger of two white dwarf (WD) stars. They are known to exhibit many spectral peculiarities, such as partial helium burning products, enhancement of s-processed material and severe hydrogen-deficiency. In this work I explore many facets of HdC evolution. I begin by creating 18 HdC models in the stellar evolution code Modules for Experiments in Stellar Astrophysics (MESA) by merging two WD progenitors and evolving the ...


Development Of A Fluxgate Magnetometer Model, Eleonora Olsmats 2022 University of New Hampshire, Durham

Development Of A Fluxgate Magnetometer Model, Eleonora Olsmats

Honors Theses and Capstones

As a part of the UNH SWFO-L1 mission to monitor space weather and the sun’s behavior, the fluxgate magnetometer is an important component to measure external magnetic fields. The basic principle of a fluxgate magnetometer is to detect changes in the ambient magnetic field by inducing a magnetic field in a ferromagnetic material via a drive winding. Each magnetometer is unique due to the ferromagnetic properties of the core material which can be seen in the hysteresis loop which is a relationship between the magnetic field strength (H) and the induced magnetic field (B). Measuring the hysteresis of a ...


Searching For Anomalous Extensive Air Showers Using The Pierre Auger Observatory Fluorescence Detector, Andrew Puyleart 2022 Michigan Technological University

Searching For Anomalous Extensive Air Showers Using The Pierre Auger Observatory Fluorescence Detector, Andrew Puyleart

Dissertations, Master's Theses and Master's Reports

Anomalous extensive air showers have yet to be detected by cosmic ray observatories. Fluorescence detectors provide a way to view the air showers created by cosmic rays with primary energies reaching up to hundreds of EeV . The resulting air showers produced by these highly energetic collisions can contain features that deviate from average air showers. Detection of these anomalous events may provide information into unknown regions of particle physics, and place constraints on cross-sectional interaction lengths of protons. In this dissertation, I propose measurements of extensive air shower profiles that are used in a machine learning pipeline to distinguish a ...


Physical Characteristics And Classification Of The Large Amplitude Variable Star V1719 Cygni, Ashley Lieber, Logan Siems, Julia Kennefick, Michael Fitzgerald 2022 University of Arkansas, Fayetteville

Physical Characteristics And Classification Of The Large Amplitude Variable Star V1719 Cygni, Ashley Lieber, Logan Siems, Julia Kennefick, Michael Fitzgerald

Inquiry: The University of Arkansas Undergraduate Research Journal

Pulsating stars are used as standard candles which are helpful in determining distances to stellar objects along with the relationship between their period and apparent luminosity. The focus of this study was the variable star, V1719 Cygni, which is often classified as a Delta (δ) Scuti star, but there exists debate that it should be classified as a RR Lyrae star due to its abnormal light curve and similar characteristics between the two variable star categories. Observational data was taken in 2019 using the Las Cumbres Observatory international telescope network. The resulting data were calibrated using comparison stars in the ...


Modeling Cherenkov Light Detection Timing For The Very Energetic Radiation Imaging Telescope Array System, Keilan Finn Ramirez 2021 California Polytechnic State University, San Luis Obispo

Modeling Cherenkov Light Detection Timing For The Very Energetic Radiation Imaging Telescope Array System, Keilan Finn Ramirez

Physics

The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an array of four 12-meter telescopes which use the Imaging Atmospheric Cherenkov Technique to conduct high-energy gamma-ray astronomy. VERITAS detects magnitude and location information associated with Cherenkov light, and uses this information to indirectly observe gamma-rays through a software reconstruction process. VERITAS also records timing information corresponding to Cherenkov light detection, and this additional information could theoretically be incorporated into the reconstruction process to improve the accuracy of gamma-ray observations. The first step to including timing information is to understand when Cherenkov light detection would be expected from a known ...


Inelastic, Exchange, And Reactive Processes In Rovibrationally Excited Collisions Of Hd With H, Boyi Zhou, Benhui Yang, Balakrishnan Naduvalath, B. K. Kendrick, Maodu Chen, P. C. Stancil 2021 University of Georgia

Inelastic, Exchange, And Reactive Processes In Rovibrationally Excited Collisions Of Hd With H, Boyi Zhou, Benhui Yang, Balakrishnan Naduvalath, B. K. Kendrick, Maodu Chen, P. C. Stancil

Chemistry and Biochemistry Faculty Publications

The HD molecule is an important coolant in early universe chemistry models and a tracer of H2 in star-forming regions. Rate coefficients for collisional excitation and de-excitation of HD rotational and vibrational levels form important ingredients in astrophysical models. While collisions with He, H2, and H are the most important, available data for H + HD collisions are largely limited to temperatures less than 1000 K for the vibrational ground state, low-lying rotational levels of the v = 1 HD vibrational level, or computed without reactive contributions. Here, through explicit quantum scattering calculations, we report extensive data for rovibrational transitions in HD ...


Terrestrial Planet Formation In A Circumbinary Disc Around A Coplanar Binary, Anna C. Childs, Rebecca G. Martin 2021 University of Nevada, Las Vegas

Terrestrial Planet Formation In A Circumbinary Disc Around A Coplanar Binary, Anna C. Childs, Rebecca G. Martin

Physics & Astronomy Faculty Publications

With N-body simulations, we model terrestrial circumbinary planet (CBP) formation with an initial surface density profile motivated by hydrodynamic circumbinary gas disc simulations. The binary plays an important role in shaping the initial distribution of bodies. After the gas disc has dissipated, the torque from the binary speeds up the planet formation process by promoting body-body interactions but also drives the ejection of planet building material from the system at an early time. Fewer but more massive planets form around a close binary compared to a single star system. A sufficiently wide or eccentric binary can prohibit terrestrial planet formation ...


Dark Matter Detection Materials, James E. Harrison IV 2021 University of North Florida

Dark Matter Detection Materials, James E. Harrison Iv

PANDION: The Osprey Journal of Research and Ideas

The purpose of this paper is to review the different methods and materials used in the detection of dark matter. Special attention is given to materials in the solid state, but other materials are briefly mentioned for the sake of completeness. After a review, we discuss the viability of each material as a detector, and determine what advantages each material has, and what method of detection works best for each material. We conclude by discussing the potential outcomes of a null detection.


Transmission Telescope Optical Dynamic Alignment, Viviana Vladutescu, Aaron J. Swank, Dzu K. Le, Calvin R. Robinson, O. Scott Sands 2021 CUNY New York City College of Technology

Transmission Telescope Optical Dynamic Alignment, Viviana Vladutescu, Aaron J. Swank, Dzu K. Le, Calvin R. Robinson, O. Scott Sands

Publications and Research

The Integrated Radio Optical Communication System (iROC) is designed to transmit data between Mars and Earth by means of radio waves at 32.67 GHz (Ka band) and laser beam (LB) at 1550 nm, both transmitted via a combined telescope/antenna called a teletenna. The iROC terminal will provide “beaconless” operations to allow full function from the outer planets. In order to point without the aid of an uplink beacon, the proof of concept presented here is addressing the need for an accurate determination and control of the relative position of the LB with respect to a reference star.

The ...


Investigation Of Shocked Basalts From Vargeão Dome And Vista Alegre: Implications For The Search For Life On Mars, Nikol Posnov 2021 The University of Western Ontario

Investigation Of Shocked Basalts From Vargeão Dome And Vista Alegre: Implications For The Search For Life On Mars, Nikol Posnov

Electronic Thesis and Dissertation Repository

Impact craters represent excellent astrobiological targets for planetary exploration missions to Mars. The impact of an asteroid or comet into a crystalline, H2O-bearing target may result in development of a hydrothermal system and increase the habitability of the substrate for the colonization of endolithic microorganisms. Given that Mars’ surface is covered by cratered basaltic rock, this study investigated target rocks and impact breccias from Vargeão Dome and Vista Alegre impact structures that formed in basalt in the Paraná Basin of Brazil.

Utilizing petrography and micro-X-ray diffraction (μXRD), the degree of shock metamorphism in plagioclase was quantitively determined. Measuring ...


A Mechanical Model For Magnetized Relativistic Blastwaves, Shunke Ai, Bing Zhang 2021 University of Nevada, Las Vegas

A Mechanical Model For Magnetized Relativistic Blastwaves, Shunke Ai, Bing Zhang

Physics & Astronomy Faculty Publications

The evolution of a relativistic blastwave is usually delineated under the assumption of pressure balance between forward- and reverse-shocked regions. However, such a treatment usually violates the energy conservation law, and is inconsistent with existing magnetohydrodynamic numerical simulation results. A mechanical model of non-magnetized blastwaves was proposed in previous work to solve the problem. In this paper, we generalize the mechanical model to the case of a blastwave driven by an ejecta with an arbitrary magnetization parameter $\sigma_{\rm ej}$. We test our modified mechanical model by considering a long-lasting magnetized ejecta and found that it is much better than ...


Testing Spiral Density-Wave Theory In Disk Galaxies Using Multi-Wavelength Image Data, Star Formation History Maps And Spatially Resolved Stellar Clusters, Mohamed Shameer Abdeen 2021 University of Arkansas, Fayetteville

Testing Spiral Density-Wave Theory In Disk Galaxies Using Multi-Wavelength Image Data, Star Formation History Maps And Spatially Resolved Stellar Clusters, Mohamed Shameer Abdeen

Graduate Theses and Dissertations

Studying galaxy structures using different wavebands enables us to observe a varietyof intrinsic galactic features and to test the validity of underlying theories in detail. Density wave theory, originally proposed by C.C. Lin and F. Shu (Lin & Shu 1964), explains the nature of the spiral arm patterns in disk galaxies as density waves that propagate through the galactic disk. From spiral galaxies to the rings of Saturn, density wave theory has had success in providing qualitative explanations of disk dynamics. However, it is now widely believed that galactic disks are dissipative systems which raises the question of whether they ...


Study Of 134in Beta-Delayed Neutron Emission And Development Of A New Generation Neutron Detector, Joseph Heideman 2021 University of Tennessee, Knoxville

Study Of 134in Beta-Delayed Neutron Emission And Development Of A New Generation Neutron Detector, Joseph Heideman

Doctoral Dissertations

Beta-delayed neutron emission in very neutron-rich nuclei plays an essential role in nuclear structure and the understanding of the astrophysical r-process. A complete description of this process requires knowledge of both steps, beta decay and neutron emission. A leading theory poses the intermediate daughter nucleus to behave as a compound nucleus. The conditions for beta-delayed neutron emission of 134In are not well described by the assumptions in the neutron pandemonium hypothesis, therein providing a unique case to this process due to the proximity to 132Sn. Single-particle states in 133Sn obvserved after neutron emission have dissimilar shell occupancy compared to neutron-hole ...


Expanding Band Parameter Analysis Methods For Hed Meteorites And V-Type Asteroids, Noah Adm Haverkamp Frere 2021 University of Tennessee, Knoxville

Expanding Band Parameter Analysis Methods For Hed Meteorites And V-Type Asteroids, Noah Adm Haverkamp Frere

Masters Theses

Vesta and Vesta-like asteroids have been convincingly linked, through visible and near-infrared (VNIR; 0.7 - 2.5 µm [micron]) spectral analysis, to a clan of basaltic achondritic meteorites – howardites, eucrites, and diogenites (HEDs). VNIR reflectance spectra of V-type asteroids and HED meteorites have two absorption features centered near 1 µm (Band I) and 2 µm (Band II) caused primarily by Fe2+ [iron] and Ca2+ [calcium] cations in pyroxene. Previous studies have shown a correlation between the mol% Fs and Wo with the central wavelengths of Band I and Band II, hereafter called Band I Center (BIC) and Band ...


Experimental Constraint On Axionlike Particles Over Seven Orders Of Magnitude In Mass, Tanya S. Roussy, Daniel A. Palken, William B. Cairncross, Benjamin M. Brubaker, Daniel N. Gresh, Matt Grau, Kevin C. Cossel, Kia Boon Ng, Yuval Shagam, Yan Zhou, Victor V. Flambaum, Konrad W. Lehnert, Jun Ye, Eric A. Cornell 2021 University of Colorado Boulder

Experimental Constraint On Axionlike Particles Over Seven Orders Of Magnitude In Mass, Tanya S. Roussy, Daniel A. Palken, William B. Cairncross, Benjamin M. Brubaker, Daniel N. Gresh, Matt Grau, Kevin C. Cossel, Kia Boon Ng, Yuval Shagam, Yan Zhou, Victor V. Flambaum, Konrad W. Lehnert, Jun Ye, Eric A. Cornell

Physics & Astronomy Faculty Publications

We use our recent electric dipole moment (EDM) measurement data to constrain the possibility that the HfF+ EDM oscillates in time due to interactions with candidate dark matter axionlike particles (ALPs). We employ a Bayesian analysis method which accounts for both the look-elsewhere effect and the uncertainties associated with stochastic density fluctuations in the ALP field. We find no evidence of an oscillating EDM over a range spanning from 27 nHz to 400 mHz, and we use this result to constrain the ALP-gluon coupling over the mass range 10-22-10-15 eV. This is the first laboratory constraint on the ALP-gluon coupling ...


The James Webb Space Telescope And Scientific Progress, Robert Astle 2021 Collin College

The James Webb Space Telescope And Scientific Progress, Robert Astle

Quest

Independent Research Paper

Research in progress for PHYS 2425: University Physics I

Faculty Mentor: Raji Kannampuzha, Ph.D.

The following paper represents research work done by students in University Physics 2425, the first half of a two-semester introductory course in physics. It is a calculus- based physics course, intended primarily for physics, chemistry, math, and engineering majors. Students are introduced to the concept of academic research by learning to ask research-focused questions and then use the library resources to pursue outside research to find answers. For this assignment, students are asked to investigate a physical science, biological science, or technology ...


A Multi-Wavelength Study Of The Disk Winds And Their Role In The Agn Studies, Maryam Dehghanian 2021 University of Kentucky

A Multi-Wavelength Study Of The Disk Winds And Their Role In The Agn Studies, Maryam Dehghanian

Theses and Dissertations--Physics and Astronomy

Active galactic nuclei (AGNs) are located at the centers of massive galaxies and are the most luminous objects in the universe. Each AGN embeds a super-massive black hole which produces outflows of gas, or winds. These winds are important because they provide a reasonable physical basis for the connections between the black hole and the properties of their host galaxy. While AGNs have been extensively studied, several fundamental questions about them are yet to be answered. These include the structure and dynamics of the central source and their winds, and questions regarding the evolution of these galaxies.

NGC 5548 is ...


Image Analysis Of Charged Bimodal Colloidal Systems In Microgravity., Adam J. Cecil 2021 University of Louisville

Image Analysis Of Charged Bimodal Colloidal Systems In Microgravity., Adam J. Cecil

Electronic Theses and Dissertations

Colloids are suspensions of two or more phases and have been topics of research for advanced, tunable materials for decades. Stabilization of colloids is typically attributed to thermodynamic mechanisms; however, recent studies have identified transport or entropic mechanisms that can potentially stabilize a thermodynamically unstable colloidal system. In this study, suspensions of silsesquioxane microparticles and zirconia nanoparticles were dispersed in a nitric acid solution and allowed to aggregate for 8-12 days in microgravity aboard the International Space Station. The suspensions were subsequently imaged periodically at 2.5x magnification. Due to the inadequacy of existing image analysis programs, the python package ...


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