Astrophysics and Astronomy Commons^™

Three Moving Groups Detected In The Lamost Dr1 Archive, Zhao J. K., Zhao G., Y. Q. Chen, T. D. Oswalt, K. F. Tan, Y. Zhang

Publications

We analyze the kinematics of thick disk and halo stars observed by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. We have constructed a sample of 7993 F, G, and K nearby main-sequence stars (d < 2 kpc) with estimates of position (x, y, z) and space velocity (U, V, W) based on color and proper motion from the Sloan Digital Sky Survey DR9 catalog. Three “phase-space overdensities” are identified in (V,√U2 + 2V 2) with significance levels of σ > 3. Two of them (the Hyades–Pleiades stream …

Monte Carlo Simulations Of Atmospheric Loss By Stellar Winds From Exoplanets, Daniel P. Violette

University Scholar Projects

Hot Jupiters are a class of extra-solar planets. Massive gas giants on the same size scale as Jupiter, they orbit their host stars closely. This proximity results in large stellar winds capable of stripping away a planet’s atmosphere. Developing a more complete understanding of atmospheric mass loss and evolution in planetary bodies is critical, and Hot Jupiter systems are accessible analogues.

This project will seek to create a computational model capable of estimating mass loss rates due to stellar winds. A Monte Carlo method is utilized to take an ensemble of single, high-energy energetic neutral particles, produced by kilo-electronvolt stellar …

Monte Carlo Simulations Of Atmospheric Loss By Stellar Winds From Exoplanets, Daniel Violette

Honors Scholar Theses

Hot Jupiters are a class of extra-solar planets. Massive gas giants on the same size scale as Jupiter, they orbit their host stars closely. This proximity results in large stellar winds capable of stripping away a planet’s atmosphere. Developing a more complete understanding of atmospheric mass loss and evolution in planetary bodies is critical, and Hot Jupiter systems are accessible analogues.

This project will seek to create a computational model capable of estimating mass loss rates due to stellar winds. A Monte Carlo method is utilized to take an ensemble of single, high-energy energetic neutral particles, produced by kilo-electronvolt stellar …

Subaru Spectroscopy And Spectral Modeling Of Cygnus A, Matthew J. Merlo, Erik S. Perlman, Robert Nikutta, Christopher Packham, Moshe Elitzur, Masatoshi Imanishi, N. A. Levenson, James T. Radomski, Itziar Aretxaga

Physics and Astronomy Faculty Publications

We present high angular resolution (~0.''5) MIR spectra of the powerful radio galaxy, Cygnus A (Cyg A), obtained with the Subaru telescope. The overall shape of the spectra agree with previous high angular resolution MIR observations, as well as previous Spitzer spectra. Our spectra, both on and off nucleus, show a deep silicate absorption feature. The absorption feature can be modeled with a blackbody obscured by cold dust or a clumpy torus. The deep silicate feature is best fit by a simple model of a screened blackbody, suggesting that foreground absorption plays a significant, if not dominant, role in shaping …

Search For Gravitational Wave Ringdowns From Perturbed Intermediate Mass Black Holes In Ligo-Virgo Data From 2005-2010, Tiffany Summerscales, The Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

We report results from a search for gravitational waves produced by perturbed intermediate mass black holes (IMBH) in data collected by LIGO and Virgo between 2005 and 2010. The search was sensitive to astrophysical sources that produced damped sinusoid gravitational wave signals, also known as ringdowns, with frequency 50≤f0/Hz≤2000 and decay timescale 0.0001≲τ/s≲0.1 characteristic of those produced in mergers of IMBH pairs. No significant gravitational wave candidate was detected. We report upper limits on the astrophysical coalescence rates of IMBHs with total binary mass 50≤M/M⊙≤450 and component mass ratios of either 1:1 or 4:1. For systems with total mass 100≤M/M⊙≤150, …

Absolute Properties Of The Eclipsing Binary Star Ap Andromedae, Claud H. Sandberg Lacy, Guillermo Torres, Francis C. Fekel, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

AP And is a well-detached F5 eclipsing binary star for which only a very limited amount of information was available before this publication. We have obtained very extensive measurements of the light curve (19,097 differential V magnitude observations) and a radial velocity curve (83 spectroscopic observations) which allow us to fit orbits and determine the absolute properties of the components very accurately: masses of 1.277 ± 0.004 and 1.251 ± 0.004 M☉, radii of 1.233 ± 0.006 and 1.1953 ± 0.005 R☉, and temperatures of 6565 ± 150 K and 6495 ± 150 K. The distance to the system is …

Dominican Big History Scholars Student-Led Focus Groups, Lizette Cabrera, Cassandra Cannon, Talia Gonzalez, Carly Holboke, Kylie Walsh, Tegist Worku, Emily Beach, Mackenzie Hagstrom, Jennifer Lucko, J. Dan May, Mojgan Behmand

Big History | Scholar Program

No abstract provided.

Continuum Polarization In Circumstellar Media, Richard Ignace

ETSU Faculty Works

See http://www.asu.cas.cz/~wg2prague/

A Four-Planet System Orbiting The K0v Star Hd 141399, Steve Vogt, R. Paul Butler, Eugenio J. Rivera, Robert I. Kibrick, Jennifer Burt, Russell Hanson, Stefano Meschiari, Gregory W. Henry, Gregory Laughlin

Information Systems and Engineering Management Research Publications

We present precision radial velocity (RV) data sets from Keck-HIRES and from Lick Observatory's new Automated Planet Finder Telescope and Levy Spectrometer on Mt. Hamilton that reveal a multiple-planet system orbiting the nearby, slightly evolved, K-type star HD 141399. Our 91 observations over 10.5 yr suggest the presence of four planets with orbital periods of 94.35, 202.08, 1070.35, and 3717.35 days and minimum masses of 0.46, 1.36, 1.22, and 0.69 MJ, respectively. The orbital eccentricities of the three inner planets are small, and the phase curves are well sampled. The inner two planets lie just outside the 2:1 resonance, suggesting …

On The Observability Of Optically Thin Coronal Hyperfine Structure Lines, Marios Chatzikos, Gary J. Ferland, R. J. R. Williams, A. C. Fabian

Physics and Astronomy Faculty Publications

We present CLOUDY calculations for the intensity of coronal hyperfine lines in various environments. We model indirect collisional and radiative transitions, and quantify the collisionally excited line emissivity in the density-temperature phase space. As an observational aid, we also express the emissivity in units of that in the 0.4-0.7 keV band. For most hyperfine lines, knowledge of the X-ray surface brightness and the plasma temperature is sufficient for rough estimates. We find that the radiation fields of both Perseus A and Virgo A can enhance the populations of highly ionized species within 1 kpc. They can also enhance line emissivity …

Electronic Device Incorporating Memristor Made From Metallic Nanowire, Douglas R. Strachan, Stephen L. Johnson

Physics and Astronomy Faculty Patents

An electronic device includes a first electrode, a second electrode and a nanowire connected between the first and second electrodes to allow electric current flow. The nanowire is made from a conductive material exhibiting a variable resistance due to electromigration. The nanowire is repeatably switchable between two states. A voltage clamp operates through feedback control to maintain the voltage across the nanowire and prevent thermal runaway.

Gemini Long-Slit Observations Of Luminous Obscured Quasars: Further Evidence For An Upper Limit On The Size Of The Narrow-Line Region, Kevin N. Hainline, Ryan C. Hickox, Jenny E. Greene, Adam D. Myers

Dartmouth Scholarship

We examine the spatial extent of the narrow-line regions (NLRs) of a sample of 30 luminous obscured quasars at 0.4 < z < 0.7 observed with spatially resolved Gemini-N GMOS long-slit spectroscopy. Using the [O III] λ5007 emission feature, we estimate the size of the NLR using a cosmology-independent measurement: the radius where the surface brightness falls to 10^–15 erg s^–1 cm^–2 arcsec^–2. We then explore the effects of atmospheric seeing on NLR size measurements and conclude that direct measurements of the NLR size from observed profiles are too large by 0.1-0.2 dex on average, as compared to measurements made to best-fit Sérsic or Voigt profiles convolved with the seeing. These data, which span a full order of magnitude in IR luminosity (log (L _{8 μm}/erg s^–1) = 44.4-45.4), …

Ua66 Ogden College Of Science & Engineering Newsletter, Cheryl Stevens, Dean

Ogden College of Science & Engineering Publications

No abstract provided.

Dust Properties Of Z~2 Infrared-Luminous Lyman Break Galaxies., Jennifer Leigh Wojno

Electronic Theses and Dissertations

Lyman break galaxies (LBGs) are well-known indicators of star formation. By analyzing the dust of moderate redshift (z ~ 2) LBGs, we can further investigate the properties of these strongly star forming galaxies at an epoch when global star formation is expected to peak. Using data observed by the Herschel satellite, we derive far-infrared fluxes for our color-selected sample of LBGs in the GOODS-S field, including a subsample of infrared-luminous LBGs (ILLBGs). This is one of the first samples of UV dropouts/partial dropouts, which are also infrared-luminous, to be studied for their far-IR properties. Fitting modified Planck curves and model …

Investigating Evidence For Different Black Hole Accretion Modes Since Redshift Z ∼ 1, A. Georgakakis, P. G. Pérez-González, N. Fanidakis, M. Salvato, J. Aird, H. Messias, J. M. Lotz, G. Barro, Li-Ting Hsu, K. Nandra, D. Rosario, M. C. Cooper, Dalibor D. Kocevski, J. A. Newman

Physics and Astronomy Faculty Publications

Chandra data in the COSMOS, AEGIS-XD and 4 Ms Chandra Deep Field South are combined with multiwavelength photometry available in those fields to determine the rest-frame U − V versus V − J colours of X-ray AGN hosts in the redshift intervals 0.1 < z < 0.6 (mean z¯=0.40) and 0.6 < z < 1.2 (mean z¯=0.85). This combination of colours provides an effective and least model-dependent means of separating quiescent from star-forming, including dust reddened, galaxies. Morphological information emphasizes differences between AGN populations split by theirU − V versus V − J colours. AGN in quiescent galaxies consist almost exclusively of bulges, while star-forming hosts are equally split between early- and late-type hosts. The position of AGN hosts on the U − V versusV − J diagram is then used to set limits on the accretion density of the …

Adaptation Of Gamma Camera System For Small Field-Of-View Applications, Melanie Carroll

Honors Capstones

No abstract provided.

Infall As A Function Of Position And Molecular Tracer In Dense Cores., Jared Alan Keown

College of Arts & Sciences Senior Theses

The standard model of prestellar core collapse suggests that this process works from the inside and moves outwards, with the fastest motions at the center. The relative abundances of many molecules also vary within cores, with certain molecules found only in specific regions characterized by narrow ranges of temperature and density. These characteristics lead to the hypothesis that the observed infall speeds in starless cores depend on both the position of the observations and the molecular tracer chosen. By measuring line emission at multiple positions across a core using an array of tracer molecules, one can determine whether these theoretical …

Multidimensional Simulations Of Non-Linear Cosmic Ray Production In Supernova Remnant Evolution, Joshua Wood

All Dissertations

When a high-mass star (& 4Msun) explodes at the end of its life, a supernova occurs, leaving its degenerate core and a fast-moving shell of matter, known as a supernova remnant (SNR). The SNR shell lasts for many thousands of years, generating emissions from low-frequency radio (~ 10-7 eV) up to γ-ray regime (~ 1015 eV). It is also believed that SNRs are the predominant source of galactic cosmic rays, accelerating a population of thermal ions, primarily protons, up to relativistic energies by means of the diffusive shock acceleration (DSA) mechanism. The small population of thermal (Boltzmann) particles, p ~ …

Search For Gravitational Wave Ringdowns From Perturbed Intermediate Mass Black Holes In Ligo-Virgo Data From 2005–2010, J. Aasi, B. P. Abbott, Matthew Benacquista, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, Cristina V. Torres

Physics & Astronomy Faculty Publications

We report results from a search for gravitational waves produced by perturbed intermediate mass black holes (IMBH) in data collected by LIGO and Virgo between 2005 and 2010. The search was sensitive to astrophysical sources that produced damped sinusoid gravitational wave signals, also known as ringdowns, with frequency 50 ≤ f0=Hz ≤ 2000 and decay timescale 0.0001 ≲ τ=s ≲ 0.1 characteristic of those produced in mergers of IMBH pairs. No significant gravitational wave candidate was detected. We report upper limits on the astrophysical coalescence rates of IMBHs with total binary mass 50 ≤ M=M⊙ ≤ 450 and component mass …

The Luminosity Function At Z ~ 8 From 97 Y-Band Dropouts : Inferences About Reionization., Kasper B. Schmidt, Tommaso Treu, Michele Trenti, Larry D. Bradley, Brandon C. Kelly, Pascal A. Oesch, Benne W. Holwerda, J. Michael Shull, Massimo Stiavelli

Faculty and Staff Scholarship

We present the largest search to date for Y-band dropout galaxies (z ∼ 8 Lyman break galaxies, LBGs) based on 350 arcmin2 of Hubble Space Telescope observations in the V, Y, J, and H bands from the Brightest of Reionizing Galaxies (BoRG) survey. In addition to previously published data, the BoRG13 data set presented here includes approximately 50 arcmin2 of new data and deeper observations of two previous BoRG pointings, from which we present 9 new z ∼ 8 LBG candidates, bringing the total number of BoRG Y-band dropouts to 38 with 25.5 mJ 27.6 (AB system). We introduce a …

The White Dwarfs Within 25 Pc Of The Sun: Kinematics And Spectroscopic Subtypes, Edward M. Sion, J. B. Holberg, Terry D. Oswalt, George P. Mccook, Richard Wasatonic, Janine Myszka

Publications

We present the fractional distribution of spectroscopic subtypes, range and distribution of surface temperatures, and kinematical properties of the white dwarfs (WDs) within 25 pc of the Sun. There is no convincing evidence of halo WDs in the total 25 pc sample of 224 WDs. There is also little to suggest the presence of genuine thick disk subcomponent members within 25 pc. It appears that the entire 25 pc sample likely belongs to the thin disk. We also find no significant kinematic differences with respect to spectroscopic subtypes. The total DA to non-DA ratio of the 25 pc sample is …

Physics Of Gamma-Ray Bursts And Multi-Messenger Signals From Double Neutron Star Mergers, He Gao

UNLV Theses, Dissertations, Professional Papers, and Capstones

My dissertation includes two parts:

Physics of Gamma-Ray Bursts (GRBs): Gamma-ray bursts are multi-wavelength transients, with both prompt gamma-ray emission and late time afterglow emission observed by telescopes in different wavelengths. I have carried out three investigations to understand GRB prompt emission and afterglow. Chapter 2 develops a new method, namely, "Stepwise Filter Correlation" method, to decompose the variability components in a light curve. After proving its reliability through simulations, we apply this method to 266 bright GRBs and find that the majority of the bursts have clear evidence of superposition of fast and slow variability components. Chapter 3 gives …

Mri Characterization Of Cobalt Dichloride-N-Acetyl Cysteine (C4) Contrast Agent Marker For Prostate Brachytherapy, Tze Yee Lim, R. Jason Stafford, Rajat J. Kudchadker, Madhuri Sankaranarayanapillai, Geoffrey Ibbott, Arvind Rao, Karen S. Martirosyan, Steven J. Frank

Physics & Astronomy Faculty Publications

Brachytherapy, a radiotherapy technique for treating prostate cancer, involves the implantation of numerous radioactive seeds into the prostate. While the implanted seeds can be easily identified on a CT image, distinguishing the prostate and surrounding soft tissues is not as straightforward. Magnetic Resonance Imaging (MRI) offers superior anatomical delineation, but the seeds appear as dark voids and are difficult to identify, thus creating a conundrum. Cobalt dichloride-N-acetylcysteine (C4) has previously been shown to be promising as an encapsulated contrast agent marker. We performed spin-lattice relaxation time (T1) and spin-spin relaxation time (T2) measurements of C4 solutions with varying cobalt dichloride …

The Catalog Of Edge-On Disk Galaxies From Sdss. I. The Catalog And The Structural Parameters Of Stellar Disks, D. V. Bizyaev, Stefan Kautsch, A. V. Mosenkov, V. P. Reshetnikov, N. Ya. Sotnikova, N. V. Yablokova

Chemistry and Physics Faculty Articles

We present a catalog of true edge-on disk galaxies automatically selected from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS). A visual inspection of the g, r, and iimages of about 15,000 galaxies allowed us to split the initial sample of edge-on galaxy candidates into 4768 (31.8% of the initial sample) genuine edge-on galaxies, 8350 (55.7%) non-edge-on galaxies, and 1865 (12.5%) edge-on galaxies not suitable for simple automatic analysis because these objects either show signs of interaction and warps, or nearby bright stars project on it. We added more candidate galaxies from RFGC, EFIGI, …

Experimental Observation Of Lasing Shutdown Via Asymmetric Gain, M. Chitsazi, S. Factor, J. Schindler, Hamidreza Ramezani, F. M. Ellis, T. Kottos

Physics & Astronomy Faculty Publications

Using a pair of coupled RLC cavities we experimentally demonstrate that amplification action can be tamed by a spatially inhomogeneous gain. Under specific conditions we observe the counterintuitive phenomenon of stabilization of the system even when the overall gain provided is increased. This behavior is directly related to lasing shutdown via asymmetric pumping, recently proposed in M. Liertzer et al. [Phys. Rev. Lett. 108, 173901 (2012)]. The analysis of other simple systems reveals the universal nature of the lasing shutdown phenomenon as having its roots in managing impedance matching.

Where Did The First Generation Of Stars Form In The Universe, Long Yan Yung, Aparna Venkatesan

Creative Activity and Research Day - CARD

The first generation of stars in the universe are expected to contain no heavy elements beyond helium, and are considered “metal-free” Population III stars (or Pop III). These metal-free stars in the early universe are predicted to have hard ionizing photon spectra and unique element yields from their supernovae, leaving signatures through the reionization of the intergalactic medium and the metal enrichment of gas in the early universe. Here, we examine the metal abundances in a variety of systems in the nearby universe, from very metal-poor Galactic halo stars to ultra-faint dwarf spheroidal galaxies, and compare them with the latest …

Psychoacoustic Effects Of High-Resolution Directivity Measurements On Room Modeling Auralizations, Nathan Eyring, Dr. Timothy Leishman

Journal of Undergraduate Research

Over the past years research has been conducted to understand how sound radiates from musical instruments. This has been done by recording a sphere of 2664 data points around a player through the process of many repetitions. This sphere is called the instrument’s directivity This data can be input into room modeling software to predict how an instrument will sound in any given location even before it is built. However there is the legitimate question of whether or not there this new data will change how room model sounds, and if someone listening would care. This research was an attempt …

Phase-Correlation And Propagation Analysis Of Near-Field Military Jet Noise, Jazz Myres, Dr. Kent Gee

Journal of Undergraduate Research

According to the Office of Naval Research (ONR), the United States Department of Veteran Affairs spent over $1 billion dollars on military hearing loss compensation in 2010 alone1. A major cause of hearing loss is exposure to high Sound Pressure Levels, which are caused by military aircraft. These severe levels and high risks are what motivate the overarching goal of all jet noise research: to attenuate the sound impact and reduce the risk of hearing loss. My research project helps this overall purpose by characterizing jet noise and innovating more complete methods of jet noise study. The purpose of this …

Development Of A Data Reduction Pipeline For The Rovor Observatory, Thayne Mccombs, Dr. Joseph Ward Moody

Journal of Undergraduate Research

The ROVOR observatory is a robotic, remotely controlled telescope in Delta, Utah. Since it is remotely controlled and semi-automated, it produces a very large amount of raw data. Unfortunately it took much longer to process and analyze the data than to acquire it, and, therefore, we had a backlog of over two years of data that was waiting to be processed. This delay in analyzing data was detrimental to monitoring projects because without the analysis of recent data it is difficult to determine the most interesting targets to observe.

Magnetic Symmetry-Mode Analysis Of La0.5 Ca0.5 Mno3, Eric Gibbs, Dr. Branton Campell

Journal of Undergraduate Research

This project focuses on solving magnetic crystal structures using symmetry-mode analysis (SMA). A crystal is an arrangement of atoms in a repeating spatial pattern with the smallest repeating unit being known as the unit cell. A magnetic crystal contains atoms with a non-zero magnetic moment. A magnetic crystal’s unit cell repeats both the atomic and magnetic structure of the crystal. Neutron diffraction is a common method for studying magnetic crystals as the diffraction pattern can be used to determine the arrangement of atoms and magnetic moments within the unit cell.