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Measurement Of Near-Threshold Proton Branching Ratios In 31s Important For Novae, Sudarsan Balakrishnan 2023 Louisiana State University

Measurement Of Near-Threshold Proton Branching Ratios In 31s Important For Novae, Sudarsan Balakrishnan

LSU Doctoral Dissertations

Classical novae are stellar explosions that contribute to the nucleosynthesis of isotopes on the proton-rich side of the valley of stability up to 40Ca. In ONe novae, the incompletely understood reaction rate of 30P(p,γ)31S is known to strongly influence the production rate of several stable isotopes such as 30Si, 31P, and 32,33,34S. A precise measurement of this reaction rate has several potential implications towards matching astrophysical observables to the physical composition of the nova site -- the observed elemental abundance ratios of O/S and S/Al have been suggested as useful `thermometers' to gauge …


Multifrequency Scintillation In The Polar Caps, Tate Colby 2022 Embry-Riddle Aeronautical University

Multifrequency Scintillation In The Polar Caps, Tate Colby

Doctoral Dissertations and Master's Theses

In the ionosphere, plasma density structures with scales sizes ranging from a few centimeters to hundreds of kilometers are capable of modifying the phase and amplitude of a radio signal in a rapid random manner in a process called scintillation. The Coherent Electromagnetic Radio Tomography (CERTO) and the Canadian High Arctic Ionospheric Network (CHAIN) are two different networks of scintillation receivers, each with a station in Resolute Bay, Canada. CERTO measures amplitude and phase signals in VHF and UHF while CHAIN measures amplitude and phase signals in the L-band. Through these measurements we can calculate the scintillation indexes, S_4 and …


Core-Collapse Supernova Simulations With Spectral Two-Moment Neutrino Transport, Ran Chu 2022 University of Tennessee, Knoxville

Core-Collapse Supernova Simulations With Spectral Two-Moment Neutrino Transport, Ran Chu

Doctoral Dissertations

The primary focus of this dissertation is to develop a next-generation, state-of-the-art neutrino kinetics capability that will be used in the context of the next-generation, state-of-the-art core-collapse supernova (CCSN) simulation frameworks \thornado\ and \FLASH.\index{CCSN} \thornado\ is a \textbf{t}oolkit for \textbf{h}igh-\textbf{or}der \textbf{n}eutrino-r\textbf{ad}iation hydr\textbf{o}dynamics, which is a collection of modules that can be incorporated into a simulation code/framework, such as \FLASH, together with a nuclear equation of state (EOS)\index{EOS} library, such as the \WeakLib\ EOS tables. The first part of this work extends the \WeakLib\ code to compute neutrino interaction rates from~\cite{Bruenn_1985} and produce corresponding opacity tables.\index{Bruenn 1985} The processes of emission, …


Collation Model For Ljs 361: [Astronomical And Astrological Tables]., Dot Porter 2022 University of Pennsylvania

Collation Model For Ljs 361: [Astronomical And Astrological Tables]., Dot Porter

Collation Models

Opening and closing sections of astronomical and astrological tables on either side of a remnant of commentaries on gospel and epistle readings. The opening section (f. 2r-9r) includes tables for calculating the day of the week for any day from 1204 to 1512; the Sunday letter from 1204 to 1736; the golden letter from 1215 to 1728; movable feasts; time variation according to latitude and longitude; the conjunction of the sun and moon from January to September from 1327 to 1367; and the hours of day and night in any day of the year, as well as lists of human …


Using Neural Network To Search For Isolated Hα Clouds In The Virgo Cluster, Audra Carver 2022 University of Alabama in Huntsville

Using Neural Network To Search For Isolated Hα Clouds In The Virgo Cluster, Audra Carver

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.


Mining The Data Cubes In Sub-Mm And Optical Astronomy, Nathanael Pichette 2022 University of Alabama in Huntsville

Mining The Data Cubes In Sub-Mm And Optical Astronomy, Nathanael Pichette

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.


Astrophysics, Cosmology And Particle Phenomenology At The Energy Frontier, Jorge Fernandez Soriano 2022 The Graduate Center, City University of New York

Astrophysics, Cosmology And Particle Phenomenology At The Energy Frontier, Jorge Fernandez Soriano

Dissertations, Theses, and Capstone Projects

This dissertation consists of two parts, treating significantly separated fields. Each part consists on several chapters, each treating a somewhat isolated topic from the rest. In each chapter, I present some of the work developed during my passage through the graduate program, which has mostly been published elsewhere.

Part I – Cosmic Rays and Particle Physics

  • Chapter 1: In this chapter we present an introduction to the topic of cosmic ray physics, with an special focus on the so-called ultra high energy cosmic rays: their potential origins, effects during their propagation between their sources and Earth, the different techniques used …


Stacking The Gamma-Ray Sky To Search For Faint Astrophysical Populations, Yuzhe Song 2022 The Graduate Center, City University of New York

Stacking The Gamma-Ray Sky To Search For Faint Astrophysical Populations, Yuzhe Song

Dissertations, Theses, and Capstone Projects

Gamma-ray emission can be generated from a wide variety of high-energy astrophysical phenomena, from stellar flares to pulsating neutron stars, and from interstellar clouds to the center of the Milky Way Galaxy. Entering the 13th year of its orbit around Earth, the Fermi Space Gamma-ray Telescope has been continually surveying the γ-ray sky with its Large Area Telescope (LAT) on board. The latest Fermi source catalog contains over 6000 sources. Yet, a lot of sources that are expected to emit γ-rays are not detected, and only small percentages of some populations are detected. For example, solar flares are detected in …


Collation Model For Ljs 300: [Calendarium And Ephemerides], Dot Porter 2022 University of Pennsylvania

Collation Model For Ljs 300: [Calendarium And Ephemerides], Dot Porter

Collation Models

Manuscript copy of the Calendarium and Ephemerides as published by Regiomontanus in 1474. The Calendarium, for 1475-1530, gives information on lunar and solar eclipses, the length of days, and the signs of the zodiac and planets. Also includes a table of time corrections (f. 11v) for cities in reference to a longitude of approximately 10 degrees east (thus making no correction for Braunschweig, Nuremberg, Ulm, or Milan). The Ephemerides, consisting only of tables updated to begin in 1480 and ending in 1506, provides positions for the sun, moon, and planets for each day of each year. The beginning of each …


Collation Model For Ljs 490: [Astronomical Compendium], Dot Porter 2022 University of Pennsylvania

Collation Model For Ljs 490: [Astronomical Compendium], Dot Porter

Collation Models

Collection of astronomical and astrological texts. Includes tables of solar declination (f. 13r), fixed stars (f. 22r), elevation of the pole star in various cities (f. 26r), new and full moons (f. 83r-84v), sightings and transits or eclipses of Venus and Mercury (f. 87r), and the position of the sun in the ecliptic (f. 87v); treatises on instruments, such as the astrolabe (f. 17r-22r, 29r-33v, 43r-49r, 50r-50v), the sundial (f. 23r-25v), the quadrant (f. 27r-28v, 78v), the Jacob's staff (baculus, f. 45r-49r, 79r, 91r), and the chilinder or traveler's dial (f. 77r-78v); treatises on other scientific subjects, such as practical …


Development Of High-Resolution Meteor Spectra Analysis, Zhangqing Yang 2022 Western University

Development Of High-Resolution Meteor Spectra Analysis, Zhangqing Yang

Undergraduate Student Research Internships Conference

Meteoroids are often billions of years old and as they ablate and ionize in the atmosphere, they give off light leaving us clues to the history of our solar system. In addition, their presence imposes serious risks to our equipment and astronauts in space. My research deals with analyzing High-Resolution Meteor Spectra, which are obtained by separating the light Meteors give off through a Diffraction Grating. Firstly, as the Meteor’s speed during ablation affects its spectrum, the position, speed, and trajectory of 40 well-tracked Meteors (picked from over 500) were determined using the programs Metal and Mirfit. Then, the spectra …


The Pursuit For Gamma-Ray Emitting Pulsar Wind Nebulae With The Fermi-Large Area Telescope, Jordan Eagle 2022 Clemson University

The Pursuit For Gamma-Ray Emitting Pulsar Wind Nebulae With The Fermi-Large Area Telescope, Jordan Eagle

All Dissertations

Pulsar wind nebulae are highly magnetized particle winds, descending from core collapse supernovae (CC SNe), and each powered by an energetic, rapidly rotating neutron star. There are at least 125 Galactic pulsar wind nebulae (PWNe) that have been discovered from radio wavelengths to TeV gamma-rays, the majority of which were first identified in radio or X-ray surveys. An increasing number of PWNe are being identified in the TeV band by ground-based air Cherenkov Telescopes such as HESS, MAGIC, and VERITAS such that they constitute the dominant source class of Galactic TeV emitters. High-energy sources like PWNe may be responsible for …


Co Molecular Spectroscopy And Spectro-Astrometry Of Protoplanetary Disks, Stanley Jensen 2022 Clemson University

Co Molecular Spectroscopy And Spectro-Astrometry Of Protoplanetary Disks, Stanley Jensen

All Dissertations

Until relatively recently, the only known planets were those in our own solar system (Mayor & Queloz, 1995). However modern instruments and techniques have revealed that planets are ubiquitous around main sequence stars over the last three decades. From this we have obtained a multitude of insights into planetary populations. For instance, while the terrestrial and gas giant planet types are both well accounted for in extra-solar systems, the arrangement of our own system with inner terrestrial planets and outer gas giants is not clearly the typical organization (van der Marel & Mulders, 2021). In fact we see that in …


Probing The Inner Structure Of Active Galactic Nuclei Through Reverberation Mapping, Viraja Chandrashekhar Khatu 2022 The University of Western Ontario

Probing The Inner Structure Of Active Galactic Nuclei Through Reverberation Mapping, Viraja Chandrashekhar Khatu

Electronic Thesis and Dissertation Repository

In the centres of massive galaxies, active galactic nuclei (AGN) are supermassive black holes, surrounded by an accretion disk of ionized gas, that release tremendous energy in the form of electromagnetic radiation. Because AGN are unresolved through telescopes, we employ reverberation mapping (RM) to study their structure. RM capitalizes on the fact that AGN are variable – the continuum emission from the accretion disk varies, and surrounding gas (in the broad-line region, BLR) responds to those variations with a positive time lag. RM translates the measured time lag into a size of the BLR. Combined with gas velocities (measured from …


Statistical Effects Of Synthetic Template Mismatch With Model Deimos Observations, Christos Kakogiannis 2022 Union College - Schenectady, NY

Statistical Effects Of Synthetic Template Mismatch With Model Deimos Observations, Christos Kakogiannis

Honors Theses

High-precision kinematics of individual stars in Milky Way satellite galaxies and globular clusters is crucial for studies of galaxy formation, cosmology, alternative gravity models, and dark matter. We tested a rigorous method that matches model DEIMOS observations of such targets with synthetic template spectra that deduces radial velocities and [Fe/H] abundances. We added noise to create a model spectrum with SNR = 30, fitted templates with different parameters to it, and calculated the
best-match velocity and the goodness of the fit. The best fits occur for templates that are close in parameter space to the model spectrum, and the fits …


A Comparison Of Exotic And Pyraf In Analyzing Exoplanet Transits, Kailei A. Gallup 2022 California Polytechnic State University, San Luis Obispo

A Comparison Of Exotic And Pyraf In Analyzing Exoplanet Transits, Kailei A. Gallup

Physics

In this paper we discuss the data analysis processes using PyRaf, a Python-based version of IRAF, which is one of the most commonly used coding softwares in the astronomy community, as well as the analysis process using EXOTIC. Additionally, we will compare the outcomes from each process to determine if either has significant benefits over the other.


Analysis Of Comet Rotation Through Modeling Of Features In The Coma, Ien Harris 2022 Mississippi State University

Analysis Of Comet Rotation Through Modeling Of Features In The Coma, Ien Harris

Theses and Dissertations

An integral field unit fiber array spectrograph was used to observe the emission spectra of radical species (C2, C3, CH, CN, and NH2) in multiple comets. The resultant azimuthal and radial division maps produced from the reduced data provide a unique method of analyzing features with these radicals in the comae, as well as how they behave over time. A Monte Carlo model was developed in order to simulate the behavior of particles from the outer nucleus and coma of each comet depending on various parameters including rotational period, outflow velocity, and active area location. The results from the model …


Optimization Of Orbital Trajectories Using Neuroevolution Of Augmenting Topologies, Nathan Wetherell 2022 University of Connecticut

Optimization Of Orbital Trajectories Using Neuroevolution Of Augmenting Topologies, Nathan Wetherell

University Scholar Projects

This project aims to determine the feasibility of using NeuroEvolution of Augmenting Topologies (NEAT), an advanced neural network evolution scheme, to optimize orbital transfer trajectories. More specifically, this project compares a genetically evolved neural network to a standard Hohmann transfer between Earth and Mars. To test these two methods, an N-body simulation environment was created to accurately determine the result of gravitational interactions on a theoretical spacecraft when combined with planned engine burns. Once created, this simulation environment was used to train the neural networks created using the NEAT Python module. A genetic algorithm was used to modify the topology …


Monitoring The M-Dwarf Host Stars Of Tess Exoplanet Candidates: Stellar Flares And Habitability, Ashley Lieber 2022 University of Arkansas

Monitoring The M-Dwarf Host Stars Of Tess Exoplanet Candidates: Stellar Flares And Habitability, Ashley Lieber

Physics Undergraduate Honors Theses

In the search for life beyond our solar system, the study of M-dwarfs has become increasingly important due to their unique characteristics including their small size, flaring capabilities, and long lifespans. Their small size allows for exoplanet detection due to observable gravitational interactions, and the stellar flares could potentially trigger prebiotic life on exoplanets in the system. Lastly, their long lifespans may provide the conditions necessary to foster prebiotic life and the development of more complex organisms over time. Flare rate is a critical factor in determining the habitability of the exoplanet due to its potential to damage or incubate …


Are Long-Period Exoplants Around Cool Stars More Common Than We Thought?, Emily Jane Safron 2022 Louisiana State University and Agricultural and Mechanical College

Are Long-Period Exoplants Around Cool Stars More Common Than We Thought?, Emily Jane Safron

LSU Doctoral Dissertations

The Kepler mission has been the catalyst for discovery of nearly 5,000 confirmed and candidate exoplanets. The majority of these candidates orbit Sun-like stars, and have orbital periods comparable to or shorter than that of the Earth, due to the selection bias inherent in the transit method and the limitations of automated transit search algorithms. We aim to develop a richer understanding of the population of exoplanets around the lowest-mass stars, the M spectral type. We are particularly interested in exoplanets with long orbital periods, which are difficult or impossible to find using standard transit search algorithms. In our study, …


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