Open Access. Powered by Scholars. Published by Universities.®

Other Astrophysics and Astronomy Commons

Open Access. Powered by Scholars. Published by Universities.®

212 Full-Text Articles 386 Authors 17623 Downloads 45 Institutions

All Articles in Other Astrophysics and Astronomy

Faceted Search

212 full-text articles. Page 1 of 7.

Detection Of Survival And Proliferation Of Sulfate Reducers Under Simulated Martian Atmospheric And Soil Conditions, Sergio Mosquera Mora 2017 University of Arkansas, Fayetteville

Detection Of Survival And Proliferation Of Sulfate Reducers Under Simulated Martian Atmospheric And Soil Conditions, Sergio Mosquera Mora

Theses and Dissertations

Numerous studies have tried to determine the survivability and proliferation of microorganisms under simulated Martian conditions. Furthermore, most of them have been focused on the ability of these microbes to cope with high brines’ salt (NaCl) concentrations inherent of the Martian surface. However, there are not studies related to the ability of bacteria to survive on subsurface environments that have increasing concentrations of sulfate compounds. For this research, a group of microorganisms known as sulfate-reducing bacteria or simply sulfate reducers were chosen due to their ability to use sulfate compounds as terminal electron acceptors to produce metabolic energy, their tolerance ...


Knotty Inflation And The Dimensionality Of Spacetime, Arjun Berera, Roman V. Buniy, Thomas W. Kephart, Heinrich Päs, João G. Rosa 2017 University of Edinburgh

Knotty Inflation And The Dimensionality Of Spacetime, Arjun Berera, Roman V. Buniy, Thomas W. Kephart, Heinrich Päs, João G. Rosa

Mathematics, Physics, and Computer Science Faculty Articles and Research

We suggest a structure for the vacuum comprised of a network of tightly knotted/linked flux tubes formed in a QCD-like cosmological phase transition and show that such a network can drive cosmological inflation. As the network can be topologically stable only in three space dimensions, this scenario provides a dynamical explanation for the existence of exactly three large spatial dimensions in our Universe.


Quantum Physics And Relativity In Lovecraft's Fiction, Garrison McCammon 2017 Ursinus College

Quantum Physics And Relativity In Lovecraft's Fiction, Garrison Mccammon

English Summer Fellows

The early twentieth century brought about some of the best and most influential horror or weird tales ever written in the English speaking world. The most impressive and most lauded author of the group composed of such figures as Algernon Blackwood, M. R. James, Arthur Machen, Clark A. Smith, and Robert E. Howard was H. P. Lovecraft. Posthumously declared the literary successor to Edgar Allan Poe, Lovecraft’s fiction and tales of terror have cast such a huge shadow that every significant author in weird writing since his passing has claimed him as a literary heir. Lovecraft’s works were ...


Investigating Brown Dwarf Atmospheres: Gravity, Dust Content, Cloud Structure And Metallicity, Kendra Kellogg 2017 The University of Western Ontario

Investigating Brown Dwarf Atmospheres: Gravity, Dust Content, Cloud Structure And Metallicity, Kendra Kellogg

Electronic Thesis and Dissertation Repository

Brown dwarfs are the lowest mass products of star formation. Their low masses don't allow them to sustain, or sometimes even begin, the thermonuclear processes that provide stars with internal energy and the thermal pressure necessary to maintain hydrostatic equilibrium. Thus, their radii and effective temperatures decrease as they age, continually changing their spectral classification. However, it is now a well-known fact that the spectral appearance of ultra-cool dwarfs is governed by more than just temperature. Factors such as gravity, metallicity and cloud distribution play an important role in the structure and composition of ultra-cool dwarf atmospheres and ultimately ...


Characterizing Cool Brown Dwarfs And Low-Mass Companions With Low-Resolution Near-Infrared Spectra, Paige Godfrey 2017 The Graduate Center, City University of New York

Characterizing Cool Brown Dwarfs And Low-Mass Companions With Low-Resolution Near-Infrared Spectra, Paige Godfrey

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

Exoplanet direct detections are reaching the temperature regime of cool brown dwarfs, motivating further understanding of the coolest substellar atmospheres. These objects, T and Y dwarfs, are numerous and isolated in the field, thus making them easier to study in detail than objects in companion systems. Brown dwarf spectral types are derived from spectral morphology and generally appear to correspond with decreasing mass and effective temperature (Teff). However, spectral subclasses of the colder objects do not share this monotonic temperature correlation, indicating that secondary parameters (gravity, metallicity, dust) significantly influence spectral morphology. These secondary atmospheric parameters can provide insight ...


Gravitational Wave Behavior At A Vacuum-Matter Interface, Jake Litterer 2017 University of Puget Sound

Gravitational Wave Behavior At A Vacuum-Matter Interface, Jake Litterer

Honors Program Theses

In classical electrodynamics, boundary conditions of the E and B fields are derived from Maxwell's equations, which are used to derive the Fresnel equations describing the behavior of a wave at an interface between media with given indices of refraction. Though electrodynamics and gravity are in some instances strikingly analogous, boundary conditions in general relativity are somewhat more opaque. We will see that while while continuity of the metric must be true in general, discontinuity of the extrinsic curvature of spacetime, while allowed by the Einstein field equations, results in a singularity in the energy-momentum tensor. This singularity is ...


Accuracy And Stability Of Integration Methods For Neutrino Transport In Core Collapse Supernovae, Kyle A. Gregory 2017 kgrego12

Accuracy And Stability Of Integration Methods For Neutrino Transport In Core Collapse Supernovae, Kyle A. Gregory

University of Tennessee Honors Thesis Projects

No abstract provided.


Detection And Characterization Of Extrasolar Planets Through Planet-Disk Dynamical Interactions, Maryam Tabeshian 2017 The University of Western Ontario

Detection And Characterization Of Extrasolar Planets Through Planet-Disk Dynamical Interactions, Maryam Tabeshian

Electronic Thesis and Dissertation Repository

Structures observed in circumstellar disks may be caused by gravitational interaction with planetary or stellar companions. These perturbed disks are often signposts of planet birth in exoplanetary systems, and offer insights into the properties of both the disk and the perturbing planets. Therefore, structures observed in these disks provide a powerful tool for detecting and studying extrasolar planetary systems. In this work, we examine the link between disk structures and nearby/embedded planets using numerical simulations of both hypothetical and observed disk systems.

We demonstrate that gaps can be opened in dynamically cold debris disks at the mean-motion resonances (MMRs ...


Fermi-Lat Daily Monitoring Observations Of The Microquasar Cygnus X-1, Austin P. Waldron, Stephen R. Hood, Arash Bodaghee 2017 Georgia College and State University

Fermi-Lat Daily Monitoring Observations Of The Microquasar Cygnus X-1, Austin P. Waldron, Stephen R. Hood, Arash Bodaghee

Georgia College Student Research Events

Detection of gamma-ray emission from microquasars is important for understanding particle acceleration in the jet, and for constraining leptonic/hadronic emission models. We present a continuation of a 1-d likelihood analysis on gamma-ray observations by Fermi-LAT (0.1-10 GeV) of the accreting black hole candidate Cygnus X-1. Combining this gamma-ray data with available X-ray monitoring data from Swift and MAXI allowed us to reveal over a dozen days (in 2008-2016) during which Cyg X-1 displayed low-significance (3-4 sigma) excesses, many of which were contemporaneous with apparent transitions in the X-rays.


Diffuse Gamma-Ray Emission From Nearby Molecular Clouds As A Probe Of Cosmic Ray Density Variations, Ryan Abrahams 2017 Graduate Center, City University of New York

Diffuse Gamma-Ray Emission From Nearby Molecular Clouds As A Probe Of Cosmic Ray Density Variations, Ryan Abrahams

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

We analyze gamma-ray emission from nearby, interstellar molecular clouds in order to calibrate current tracers of the interstellar medium and to probe local cosmic ray gradients. Gamma-rays detected by the Fermi Gamma-ray Space Telescope are created when cosmic rays collide with atomic nuclei in the interstellar medium, and thus provide a unique, unbiased view of the distribution of gas. The gamma-ray flux per proton in the interstellar medium, also known as the gamma-ray emissivity, contains information about the density of high energy cosmic rays. These cosmic rays are born in supernovae shock waves and diffuse throughout the Galaxy. The cosmic ...


Intergalactic Hi And Ovi: A Survey Of 259 Low-Z Cos Absorbers With Reference To Ionization Mechanics, Shannon Osborne 2017 University of Colorado, Boulder

Intergalactic Hi And Ovi: A Survey Of 259 Low-Z Cos Absorbers With Reference To Ionization Mechanics, Shannon Osborne

Undergraduate Honors Theses

Modern astrophysics still lacks a strong understanding of the Intergalactic Medium (IGM), particularly the Warm-Hot Intergalactic Medium (WHIM; T = 105 – 107 K). To better understand the distribution and temperature of this gas, absorption-line observations along AGN sight lines from the Cosmic Origins Spectrograph onboard the Hubble Space Telescope (COS/HST) were analyzed (see Danforth et al. 2016). Here we present the largest analysis to date of IGM systems detected in both HI and OVI: 259 absorbers along 52 sight lines. We separate these systems into aligned and non-aligned categories based on the velocity separation of the HI and ...


Alignment Of The Western And Eastern Passage Tombs At Knowth Tomb 1, Frank Prendergast, Tom Ray 2017 Dublin Institute of Technology

Alignment Of The Western And Eastern Passage Tombs At Knowth Tomb 1, Frank Prendergast, Tom Ray

Book/Book Chapter

This report presents a summary account of two surveys undertaken by the authors to determine and interpret the alignments of the western and eastern passage tombs at Knowth, Co. Meath. The findings indicate that contrary to earlier suggestions, the eastern passage and the western passage (inner and outer) are not aligned towards sunrise and sunset respectively at the period of the vernal and autumnal equinoxes.


Observations And Light Curve Analysis Of Transiting Extra-Solar Planets, Clark M. Holcomb 2016 Stephen F Austin State University

Observations And Light Curve Analysis Of Transiting Extra-Solar Planets, Clark M. Holcomb

Electronic Theses and Dissertations

The purpose of this research was to perform the procedures to study transiting exoplanets in their entirety, from the data collection process to determining physical characteristics and orbital properties. The research was conducted with two telescopes of different sizes (16” and 12”) at multiple sites in order to refine the detection process. Both Maxim DL and Mira Pro x64 software were used to process the resulting images. The PHOEBE program was used to model the data to determine the properties of the exoplanets, which were then compared to the results obtained by other astronomers. The data collection process as well ...


Commercial Space Situational Awareness (Ssa) Capabilities And Their Benefits For Civilian Space Traffic Management (Stm), Mark A. Skinner 2016 Boeing

Commercial Space Situational Awareness (Ssa) Capabilities And Their Benefits For Civilian Space Traffic Management (Stm), Mark A. Skinner

Space Traffic Management Conference

Paralleling (but lagging) satellite development, SSA, long the sole domain of sophisticated militaries, now includes commercial providers. These commercial capabilities, identified as beneficial to the sustainable use of outer space[1], have demonstrated technical sophistication sufficient to positively contribute to the mitigation of satellite interference and provide actionable SSA information. Utilizing small optical telescopes, these entities are able to determine the orbits of objects in the geosynchronous orbit (GSO) to sizes as small as 1 m2, with measured positional uncertainties of 10s of meters, on the order of the size of a modern communications satellite. These techniques can benefit ...


High Power Optically Pumped Semiconductor Lasers For Sodium Guidestar Applications, Shawn W. Hackett 2016 University of New Mexico

High Power Optically Pumped Semiconductor Lasers For Sodium Guidestar Applications, Shawn W. Hackett

Optical Science and Engineering ETDs

Optically pumped semiconductor lasers (OPSLs) are shown to provide a much more compact and less expensive source for illumination of the sodium layer of the mesosphere for use as a sodium laser guidestar via single and two photon excitation schemes. This represents a revolution in laser guidestar technology as the cost, size, and power requirements for a laser guidestar system are shown to have been decreased by an order of magnitude with guidestar performance shown to be similar to previous sources. Sodium laser guidestar sources for broadband simultaneous illumination of multiple lines are developed and simulated. Simulations are then compared ...


Exoplanet Research: Differential Photometry For Kepler 6b, Garrett T. Benson, Charlotte Alexandra Olsen 2016 Humboldt State University

Exoplanet Research: Differential Photometry For Kepler 6b, Garrett T. Benson, Charlotte Alexandra Olsen

ideaFest: Interdisciplinary Journal of Creative Works and Research from Humboldt State University

No abstract provided.


Measurement And Modeling Of Cosmic Ray Exposure For Supercdms Dark Matter Detectors., Kameron McCall, John Orrell, Jared Yamaoka 2016 University of Houston - Main

Measurement And Modeling Of Cosmic Ray Exposure For Supercdms Dark Matter Detectors., Kameron Mccall, John Orrell, Jared Yamaoka

STAR (STEM Teacher and Researcher) Presentations

Dark matter is an unknown type of matter that composes roughly 27% of the observable universe and, as cosmological structure models suggest, the earth should be passing through a “dark halo” of this unknown matter present in the Milky Way galaxy. As we pass through this halo, the Super Cryogenic Dark Matter Search (SuperCDMS) experiment aims to directly detect dark -matter particles. Though many dark matter particle candidates exist, SuperCDMS focuses on the detection of particles called WIMPS (weakly interacting massive particles) as predicted by super-symmetric theories beyond the standard model. Due to the high-sensitivity of the germanium detectors employed ...


High Temperature Condensate Clouds In Super-Hot Jupiter Atmospheres, H. R. Wakeford, Channon Visscher, Nikole K. Lewis, Avi M. Mandell 2016 University of Exeter

High Temperature Condensate Clouds In Super-Hot Jupiter Atmospheres, H. R. Wakeford, Channon Visscher, Nikole K. Lewis, Avi M. Mandell

Faculty Work Comprehensive List

Deciphering the role of clouds is central to our understanding of exoplanet atmo- spheres, as they have a direct impact on the temperature and pressure structure, and observational properties of the planet. Super-hot Jupiters occupy a temperature regime similar to low mass M-dwarfs, where minimal cloud condensation is expected. However, observations of exoplanets such as WASP-12b (Teq∼2500 K) result in a transmission spectrum indicative of a cloudy atmosphere. We re-examine the temperature and pressure space occupied by these super-hot Jupiter atmospheres, to explore the role of the initial Al- and Ti-bearing condensates as the main source of cloud material ...


Fundamental Parameters Of The Lowest Mass Stars To The Highest Mass Planets, Joseph C. Filippazzo 2016 The Graduate Center, City University of New York

Fundamental Parameters Of The Lowest Mass Stars To The Highest Mass Planets, Joseph C. Filippazzo

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

The physical and atmospheric properties of ultracool dwarfs are deeply entangled due to the degenerate effects of mass, age, metallicity, clouds and dust, activity, rotation, and possibly formation mechanism on their observed properties. Accurate fundamental parameters for a wide range of substellar objects are crucial to testing stellar and planetary formation theories. To determine these quantities, we construct flux-calibrated spectral energy distributions (SEDs) for 234 M, L, T, and Y dwarfs and calculate bolometric luminosity (Lbol), effective temperature (Teff), mass, surface gravity, radius, spectral indexes, synthetic photometry, and bolometric corrections (BCs) for each object. We use these results ...


Examination Of Resonant Modes In Microwave Cavities, Sophia Schwalbe 2016 Embry-Riddle Aeronautical University

Examination Of Resonant Modes In Microwave Cavities, Sophia Schwalbe

College of Arts & Sciences

The Axion Dark Matter eXperiment (ADMX) looks to detect dark matter axion particles by using microwave cavities in a high magnetic field to convert the axion's mass energy to a detectable photon. The photon frequency corresponds to the axion mass. Tuning elements in the cavities allow the resonant frequency to be changed but only certain modes couple to the axion. Interactions with additional resonant modes that do not couple to the axion cause unobservable regions in the frequency range. This research investigated new methods to move the additional resonant modes in order to observe these regions.


Digital Commons powered by bepress