Astrophysics and Astronomy Commons^™

Precipitation And Release Of Solar Energetic Particles From The Solar Coronal Magnetic Field, Ming Zhang, Lulu Zhao

Aerospace, Physics, and Space Science Faculty Publications

Most solar energetic particles (SEPs) are produced in the corona. They propagate through complex coronal magnetic fields subject to scattering and diffusion across the averaged field lines by turbulence. We examine the behaviors of particle transport using a stochastic 3D focused transport simulation in a potential field source surface model of coronal magnetic field. The model is applied to an SEP event on 2010 February 7. We study three scenarios of particle injection at (i) the compact solar flare site, (ii) the coronal mass ejection (CME) shock, and (iii) the EUV wave near the surface. The majority of particles injected …

The Quadruple-Lined, Doubly Eclipsing System V482 Persei, Guillermo Torres, Claud H. Sandberg Lacy, Francis C. Fekel, Marek Wolf, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

We report spectroscopic and differential photometric observations of the A-type system V482 Per, which reveal it to be a rare hierarchical quadruple system containing two eclipsing binaries. One binary has the previously known orbital period of 2.4 days and a circular orbit, and the other a period of 6 days, a slightly eccentric orbit (e = 0.11), and shallow eclipses only 2.3% deep. The two binaries revolve around their common center of mass in a highly elongated orbit (e = 0.85) with a period of 16.67 yr. Radial velocities are measured for all components from our quadruple-lined spectra and are …

Three Dimensional View Of The Syk/Ads Duality, Sumit R. Das, Antal Jevicki, Kenta Suzuki

Physics and Astronomy Faculty Publications

We show that the spectrum of the SYK model can be interpreted as that of a 3D scalar coupled to gravity. The scalar has a mass which is at the Breitenholer-Freedman bound of AdS₂, and subject to a delta function potential at the center of the interval along the third direction. This, through Kaluza-Klein procedure on AdS₂ × (S¹)/Z₂, generates the spectrum reproducing the bi-local propagator at strong coupling. Furthermore, the leading 1/J correction calculated in this picture reproduces the known correction to the poles of the SYK propagator, providing …

Photoelectrochemical Cell Including Ga(SbX)N1-X Semiconductor Electrode, Madhu Menon, Michael Sheetz, Mahendra Kumar Sunkara, Chandrashekhar Pendyala, Swathi Sunkara, Jacek B. Jasinksi

Physics and Astronomy Faculty Patents

The composition of matter comprising Ga(Sb_x)N_1−x where x=0.01 to 0.06 is characterized by a band gap between 2.4 and 1.7 eV. A semiconductor device includes a semiconductor layer of that composition. A photoelectric cell includes that semiconductor device.

Holographic Entanglement Entropy Of A 1 + 1 Dimensional P-Wave Superconductor, Sumit R. Das, Mitsutoshi Fujita, Bom Soo Kim

Physics and Astronomy Faculty Publications

We examine the behavior of entanglement entropy S _A ^EE of a subsystem A in a fully backreacted holographic model of a 1 + 1 dimensional p wave superconductor across the phase transition. For a given temperature, the system goes to a superconducting phase beyond a critical value of the charge density. The entanglement entropy, considered as a function of the charge density at a given temperature, has a cusp at the critical point. In addition, we find that there are three different behaviors in the condensed phase, depending on the subsystem size. For a subsystem size l smaller than …

Zr-Doped Tio2 As A Thermostabilizer In Plasmon-Enhanced Dye-Sensitized Solar Cells, Anastasia Pasche, Bernd Grohe, Silvia Mittler, Paul A. Charpentier

Physics and Astronomy Publications

Harvesting solar energy is a promising solution toward meeting the world’s evergrowing energy demand. Dye-sensitized solar cells (DSSCs) are hybrid organic–inorganic solar cells with tremendous potential for commercial application, but they are plagued by in efficiency due to their poor sunlight absorption. Plasmonic silver nanoparticles (AgNPs) have been shown to enhance the absorptive properties of DSSCs, but their plasmonic resonance can cause thermal damage resulting in cell deterioration. Hence, the influence of Zr-doped TiO2 on the efficiency of plasmon-enhanced DSSCs was studied, showing that 5 mol.% Zr-doping of the photoactive TiO2 material can improve the photovoltaic performance of DSSCs by …

Photonic Band Structure Of Diamond Colloidal Crystals In A Cholesteric Liquid Crystal, Setarehalsadat Changizrezaei, Colin Denniston

Physics and Astronomy Publications

In this paper, we demonstrate the presence of a photonic band gap for a diamond lattice structure made of particles with normal anchoring inside a cholesteric liquid crystal. As is typical for liquid crystals (LCs), there is considerable contrast between the dielectric constant parallel ε∥ and perpendicular ε⊥ to the director, with ε∥/ε⊥∼4 here. It is shown that the size of the photonic band gap is directly related to the size of colloidal particles and the contrast between the dielectric constant in the particles and the extreme values of ε in the LC medium (one needs either ε in the …

The Formation Of Fine-Grained Chondrule Rims In Unequilibrated Ordinary Chondrites, John Bigolski

Dissertations, Theses, and Capstone Projects

Fine-grained rims are ubiquitous, non-igneous, features that completely or partially envelope the majority of chondrules within the least equilibrated of the unequilibrated ordinary chondrites (UOCs). A detailed examination of such rims in 4 UOC samples less than petrologic type 3.2 was conducted in order to 1) characterize the relative distribution of rims within chondrite samples, 2) inspect differences between fine-grained rims and adjacent matrix material, 3) petrologically analyze the rims and their relationships with chondrule cores, 4) characterize an ungrouped UOC, Northwest Africa 5717, 5) conduct a microanalytical investigation of rim / matrix boundaries to discern relative chronologies of fine-grained …

Influence Of Velocity Fluctuations On The Kelvin-Helmholtz Instability And Its Associated Mass Transport, Katariina Nykyri, Xuanye Ma, Andrew Dimmock, Claire Foullon, Antonius Otto, Adnane Osmane

Publications

Kelvin-Helmholtz instability (KHI) and associated magnetic reconnection and diffusion processes provide plasma transport from solar wind into the magnetosphere. The efficiency of this transport depends on the magnetosheath and magnetospheric plasma and field properties at the vicinity of the magnetopause. Our recent statistical study using data from the Time History of Events and Macroscale Interactions during Substorms spacecraft indicates that the amplitude of the magnetosheath velocity fluctuations perpendicular to the magnetopause can be substantial. We have performed a series of local macroscale 2.5-dimensional magnetohydrodynamic simulations of the KHI during strongly northward interplanetary magnetic field and with the initial plasma parameters …

Effect Of Observational Cadence On Orbit Determination For Synthetic Near-Earth Objects, Thomas G. Endicott

Graduate Masters Theses

Near-Earth Objects (NEOs) are generally small, dark, and fast-moving. Multiple observations over time are necessary to constrain NEO orbits. Orbits based on observational data are inherently uncertain. Here we describe code written in Python and Fortran used to generate synthetic asteroids and compare calculated orbital fit based on noisy ephemeris using the a distance criteria, D-value. Observational sessions separated by more than one month produce very good orbital fits (low D-values) even at the highest noise level. Daily observational sessions show the highest D-values, as expected, since observed points on the orbital ellipse are not well separated. D-value is closely …

Space Telescope And Optical Reverberation Mapping Project. Vii. Understanding The Ultraviolet Anomaly In Ngc 5548 With X-Ray Spectroscopy, S. Mathur, A. Gupta, K. Page, R. W. Pogge, Y. Krongold, M. R. Goad, S. M. Adams, M. D. Anderson, P. Arévalo, A. J. Barth, C. Bazhaw, T. G. Beatty, M. C. Bentz, A. Bigley, S. Bisogni, G. A. Borman, T. A. Boroson, M. C. Bottorff, W. N. Brandt, A. A. Breeveld, J. E. Brown, J. S. Brown, E. M. Cackett, G. Canalizo, M. T. Carini, K. I. Clubb, J. M. Comerford, C. T. Coker, E. M. Corsini, D. M. Crenshaw, Gary J. Ferland

Physics and Astronomy Faculty Publications

During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the …

New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. X. Hd 96511, Hr 7578, And Kz Andromedae, Francis C. Fekel, Gregory W. Henry, Jocelyn Tomkin

Information Systems and Engineering Management Research Publications

From an extensive number of newly acquired radial velocities we determine the orbital elements for three late-type dwarf systems, HD 96511, HR 7578, and KZ And. The orbital periods are 18.89737 ± 0.00002, 46.81610 ± 0.00006, and 3.0329113 ± 0.0000005 days, respectively, and all three systems are eccentric, although KZ And is just barely so. We have detected lines of the secondary of HD 96511 for the first time. The orbital dimensions (a1 sin i and a2 sin i) and minimum masses (m1 sin3 i and m2 sin3 i) of the binary components all have accuracies of 0.2% or better. …

Inside-Out Growth Or Inside-Out Quenching? Clues From Colour Gradients Of Local Galaxies, Jianhui Lian, Renbin Yan, Michael Blanton, Xu Kong

Physics and Astronomy Faculty Publications

We constrain the spatial gradient of star formation history (SFH) within galaxies using the colour gradients in NUV − u (where NUV stands for near-ultraviolet) and u − i for a local spatially resolved galaxy sample. By splitting each galaxy into an inner and an outer part, we find that most galaxies show negative gradients in these two colours. We first rule out dust extinction gradient and metallicity gradient as the dominant source for the colour gradient. Then using stellar population models, we explore variations in SFH to explain the colour gradients. As shown by our earlier work, a two-phase …

Ua12/2/1 College Heights Herald, Vol. 93, No. 2, Wku Student Affairs

WKU Administration Documents

WKU campus newspaper reporting campus, athletic and Bowling Green, Kentucky news. This issue contains articles:

• Kast, Monica. Total Solar Eclipse Lowers Temperatures
• Collins, Emma. Students Receive a Gouda Opportunity – Hilltopper Creamery
• DeLetter, Emily. Dean of College of Education to Retire After 28 Years – Sam Evans
• Ziege, Nicole. Student Government Association Has First Meeting of New School Year
• Alvey, Rebekah. New Program Supports First-generation Students – Intercultural Student Engagement Center
• Collins, Emma. Advertising & Public Relations Officially Change Departments
• Gibson, Helen. Hello from the WKU Talisman
• King, Jennifer. Editorial Cartoon re: Donald Trump
• Leonard, Nicole. Your Opinion, Not Theirs …

Ua12/2/1 College Heights Herald, Vol. 93, No. 1, Wku Student Affairs

WKU Administration Documents

WKU campus newspaper reporting campus, athletic and Bowling Green, Kentucky news. This issue contains articles:

• The Great American Eclipse
• Kast, Monica. Timothy Caboni Talks Budget in Meeting with Editors
• DeLetter, Emily. Back Home – Timothy Caboni
• Collins, Emma. Campus Construction Continues with Completion of Restaurant – The Den
• Ziege, Nicole. Student Government Association President Signs Anti-discrimination Letter – Andi Dahmer
• Alvey, Rebekah. New Space Serves as Link to Downtown Businesses – Gordon Ford College of Business
• Henderson, Andrew. Hey, How Are Ya?
• Editorial Cartoon re: Eclipsse
• Huff, Taylor. Eclipse of Morality – U.S. Government
• Gabhart, Ebonee. Analyzing What Constitutes a …

Oxidization Of Al And A-Si As A Protective Layer, Yhoshua Wug

Student Works

Arguably, the best chance to produce a IR-optical-UV-EUV mirror for a future space observatory is a multilayer mirror coated by a thin bare aluminum layer. Using an Al layer presents challenges that have to be overcome first. Al oxidizes rapidly as soon as it comes in contact with the atmosphere. One solution is to block the oxidation of Al by covering the mirror with a protective layer and remove it once the mirror is in space. freshly, deposited a-Si would be a good candidate for protecting the mirror. Removing it in space also presents some challenges. The best way to …

Observing Kelt Candidate Objects In The Search For Transiting Exoplanets, Maria Martinez

Student Works

The main goal of this project was to learn how to participate and be a part of a real observational team. We worked with the KELT exoplanet search project. While working with the KELT project we hoped to be able to confirm a candidate object as a planet. However, trying to discover a transiting planet was not our main goal for the summer. In addition, we also set out to learn how to work in an observatory, operate telescopes, and process data. The different objects we observed throughout the summer were not all determined to be transiting exoplanets, but we …

Developing Instrumentation For Fabricating And Characterizing Thin Film Aluminum Mirrors, P. Claire Segura

Student Works

The best material for constructing a mirror for a broad-bandwidth telescope that is also capable of reflecting EUV light is pure aluminum. In order to test how the reflectance of aluminum in the EUV range changes as it oxidizes, a system has been constructed that allows a thin aluminum mirror to be constructed inside of a vacuum, where its reflectance can then be tested immediately. Because the experiment must take place in a vacuum, it must also be controlled remotely through a computer program, which manages the mirror fabrication process as well as the collection and analysis of reflectance data. …

Vacuum Birefringence, The Photon Anomalous Magnetic Moment And The Neutron Star Rx J1856.5−3754, Sree Ram Valluri, J.W. Mielniczuk, Farrukh Chishtie, D. Lamm, S. Auddy

Physics and Astronomy Publications

We analyse the spectrum of the Hamiltonian of a photon propagating in a strong magnetic field B ∼ B_cr, where Bcr=m2e≃4.4×1013" role="presentation">Bcr=m2e≃4.4×1013 G is the Schwinger critical field. We show that the anomalous magnetic moment of a photon in the one-loop approximation is a non-decreasing function of the magnetic field B in the range 0 ≤ B ≤ 30 B_cr. We provide a numerical representation of the expression for the anomalous magnetic moment in terms of special functions. We find that the anomalous magnetic moment μ_γ of a photon for B = 30 B …

Differential Photometry Of High Mass X-Ray Binaries And Be Stars And Determining Standard Stars, Anne Blackwell

Student Works

Building off of the previously established Hα index (Joner & Hintz 2015), I use differential photometry to study high mass x-ray binaries and Be stars using the Hα index to define their level of activity. Specifically I focused of Cygnus X-1 and X Perseus. I took data on Cygnus X-1 (X Perseus will be studied later in the year) to look at its long and short term activity. Data analyzed using differential photometry is merged with previously collected spectroscopic data to show a seamless flow of results between techniques. I also defined the Hα values of 10 stars in the …

Limb Darkening And Planetary Transits: Testing Center-To-Limb Intensity Variations And Limb-Darkening Directly From Model Stellar Atmospheres, Hilding R. Neilson, Joseph T. Mcneil, Richard Ignace, John B. Lester

ETSU Faculty Works

The transit method, employed by Microvariability and Oscillation of Stars (MOST), Kepler, and various ground-based surveys has enabled the characterization of extrasolar planets to unprecedented precision. These results are precise enough to begin to measure planet atmosphere composition, planetary oblateness, starspots, and other phenomena at the level of a few hundred parts per million. However, these results depend on our understanding of stellar limb darkening, that is, the intensity distribution across the stellar disk that is sequentially blocked as the planet transits. Typically, stellar limb darkening is assumed to be a simple parameterization with two coefficients that are derived …

Entanglement Entropy With Background Gauge Fields, Bom Soo Kim

Physics and Astronomy Faculty Publications

We study the entanglement entropy, the Rényi entropy, and the mutual (Rényi) information of Dirac fermions on a 2 dimensional torus in the presence of constant gauge fields. We derive their general formulas using the equivalence between twisted boundary conditions and the background gauge fields. Novel and interesting physical consequences have been presented in arXiv:1705.01859. Here we provide detailed computations of the entropies and mutual information in a low temperature limit, a large radius limit, and a high temperature limit. The high temperature limit reveals rather different physical properties compared to those of the low temperature one: there exist …

Energy Dependence Of J/Ψ Production In Au + Au Collisions At √SNn = 39, 62.4 And 200 Gev, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

The inclusive J/ψ transverse momentum spectra and nuclear modification factors are reported at midrapidity (|y| < 1.0) in Au + Au collisions at √s_NN = 39, 62.4 and 200 GeV taken by the STAR experiment. A suppression of J/ψ production, with respect to the production in p + p scaled by the number of binary nucleon–nucleon collisions, is observed in central Au + Au collisions at these three energies. No significant energy dependence of nuclear modification factors is found within uncertainties. The measured nuclear modification factors can be described by model calculations that take into account both suppression of direct J/ψ production due to …

On The Binary Nature Of Massive Blue Hypergiants: High-Resolution X-Ray Spectroscopy Suggests That Cyg Ob2 12 Is A Colliding Wind Binary - Iopscience, Lidia M. Oskinova, David P. Huenemoerder, Wolf-Rainer Hamann, Tomer Shenar, A. A.C. Sander, Richard Ignace, H. Todt, R. Hainich

ETSU Faculty Works

The blue hypergiant Cyg OB2 12 (B3Ia+) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using the Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism depopulating the metastable upper levels of the forbidden lines of the He-like ions Si xivand Mg xii. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only at the photosphere …

Stellar Stream Candidates In The Solar Neighborhood Found In The Lamost Dr3 And Tgas, X. L. Liang, Terry Oswalt, J. K. Zhao, Y. Q. Chen, G. Zhao

Publications

We have cross-matched the LAMOST DR3 with the Gaia DR1 TGAS cata- logs and obtained a sample of 166,827 stars with reliable kinematics. A technique based on the wavelet transform was applied to detect significant overdensities in velocity space among five subsamples divided by spatial position. In total, 16 sig- nificant overdensities of stars with very similar kinematics were identified. Among these, four are new stream candidates and the rest are previously known groups. Both the U-V velocity and metallicity distributions of the local sample show a clear gap between the Hercules structure and the Hyades-Pleiades structure. The U-V positions …

The Sdss-Iv Manga Sample: Design, Optimization, And Usage Considerations, David A. Wake, Kevin Bundy, Aleksandar M. Diamond-Stanic, Renbin Yan, Michael R. Blanton, Matthew A. Bershady, José R. Sánchez-Gallego, Niv Drory, Amy Jones, Guinevere Kauffmann, David R. Law, Cheng Li, Nicholas Macdonald, Karen Masters, Daniel Thomas, Jeremy Tinker, Anne-Marie Weijmans, Joel R. Brownstein

Physics and Astronomy Faculty Publications

We describe the sample design for the SDSS-IV MaNGA survey and present the final properties of the main samples along with important considerations for using these samples for science. Our target selection criteria were developed while simultaneously optimizing the size distribution of the MaNGA integral field units (IFUs), the IFU allocation strategy, and the target density to produce a survey defined in terms of maximizing signal-to-noise ratio, spatial resolution, and sample size. Our selection strategy makes use of redshift limits that only depend on i-band absolute magnitude (M_i ), or, for a small subset of our sample, …

An Ultrahot Gas-Giant Exoplanet With A Stratosphere, Thomas M. Evans, David K. Sing, Tiffany Kataria, Jayesh M. Goyal, Nikolay Nikolov, Hannah R. Wakeford, Drake Deming, Mark S. Marley, David S. Amundsen, Gilda E. Ballester, Joanna K. Barstow, Lofti Ben-Jaffel, Vincent Bourrier, Lars A. Buchhave, Ofer Cohen, David Ehrenreich, Antonio García Muñoz, Gregory W. Henry, Heather Knutson, Panayotis Lavvas, Alain Lecavelier Des Etangs, Nikole K. Lewis, Mercedes López-Morales, Avi M. Mandell, Jorge Sanz-Forcada, Pascal Tremblin, Roxana Lupu

Information Systems and Engineering Management Research Publications

Infrared radiation emitted from a planet contains information about the chemical composition and vertical temperature profile of its atmosphere. If upper layers are cooler than lower layers, molecular gases will produce absorption features in the planetary thermal spectrum. Conversely, if there is a stratosphere—where temperature increases with altitude—these molecular features will be observed in emission. It has been suggested that stratospheres could form in highly irradiated exoplanets, but the extent to which this occurs is unresolved both theoretically and observationally. A previous claim for the presence of a stratosphere remains open to question, owing to the challenges posed by the …

A Vision For Canadian Space Exploration, Ilaria Caiazzo, Sarah C. Gallagher, Jeremy Heyl

Physics and Astronomy Publications

We propose a sustained and balanced program in space exploration to fuel innovation in the space sector, support Canada's world-leading space researchers, inspire the next generation of scientists and innovators, and create thousands of highly skilled, well-paying jobs for Canadians. During the next decade we recommend a total investment of approximately $1B, increasing to $1.3B in each decade that follows, including a regular flagship mission that Canada would lead and a constellation of smaller missions, either led by Canada or in collaboration with international partners.

Evaluation Of Radiation And Design Criteria For A Lunar Habitat, Hayley E. Bower, Daniel Gomez, Antonio Bobet, Julio A. Ramirez, Shirley J. Dyke, H. Jay Melosh

The Summer Undergraduate Research Fellowship (SURF) Symposium

Extraterrestrial habitation has long been the object of science fiction, and experts in the fields of science and engineering have proposed many designs for a lunar base. The research conducted has focused on either structural stability, radiation protection, or meteorite-impact vulnerabilities, but rarely have these been considered together. The Resilient ExtraTerrestrial Habitats (RETH) project aims to design a lunar habitat from a hazards perspective, considering general degradation, meteorite impacts, seismic activity, radiation exposure, thermal extremes, and geomagnetic storms in addition to the physiological, psychological, and sociological aspects of astronauts living in such a habitat. Several members of the RETH team …

Magnetospherically-Trapped Dust And A Possible Model For The Unusual Transits At Wd1145+017, J. Farihi, Ted Von Hippel, J. E. Pringle

Publications

The rapidly evolving dust and gas extinction observed towardsWD1145+017 has opened a real-time window onto the mechanisms for destruction-accretion of planetary bodies onto white dwarf stars, and has served to underline the importance of considering the dynamics of dust particles around such objects. Here it is argued that the interaction between (charged) dust grains and the stellar magnetic field is an important ingredient in understanding the physical distribution of infrared emitting particles in the vicinity of such white dwarfs. These ideas are used to suggest a possible model for WD 1145+017 in which the unusual transit shapes are caused by …