Measurements Of The Angular Cross-Sections Of The Decay Products Of Proton Capture By Lithium-6,
2012
Valparaiso University
Measurements Of The Angular Cross-Sections Of The Decay Products Of Proton Capture By Lithium-6, Benjamin Barber
Symposium on Research and Creative Expression (SORCE)
We have studied the nuclear reaction Li-6 + p => He-3 + He-4 using protons from the 200-keV linear accelerator located in the Manning Nuclear Physics Laboratory in the Neils Science Center. We have measured the angular distribution and energy of the resulting He-3 and He-4 nuclei. Measurements were made using a Si surface barrier detector. The incident proton energy was 125 keV, and the angular measurements were made between 150 and 120 degrees downstream of the beam. Results and highlights are presented.
The Reduction And Reporting Of Data On Proto-Planetary Nebulae From Two Observatories,
2012
Valparaiso University
The Reduction And Reporting Of Data On Proto-Planetary Nebulae From Two Observatories, Wesley Cheek
Symposium on Research and Creative Expression (SORCE)
I am documenting the light variability in a sample of proto-planetary nebulae (PPNs) observed from two observatories. PPNs are stars in the stage of evolution between the AGB and planetary nebula phases. I analyzed the digital images of the data taken on 34 nights from the SARA-South observatory located in Cerro Tololo, Chile along with data taken from the SARA-North Observatory located in Tucson, Arizona. This was done to obtain quantitative measurements of the brightness variations over time. Once I had this information for each object, I plotted light curves, which can be used to document the amplitudes and possible …
Section Abstracts: Astronomy, Mathematics And Physics With Materials Science,
2012
Old Dominion University
Section Abstracts: Astronomy, Mathematics And Physics With Materials Science
Virginia Journal of Science
Abstracts of the Astronomy, Mathematics, and Physics with Material Science Section for the 90th Annual Meeting of the Virginia Academy of Science, May 23-25, 2012, Norfolk State University, Norfolk, Virginia
1112+3548_Nir_Spex,
2012
City University of New York (CUNY)
The S4g Perspective On Circumstellar Dust Extinction Of Asymptotic Giant Branch Stars In M100.,
2012
Max-Planck-Institut für Astronomie
The S4g Perspective On Circumstellar Dust Extinction Of Asymptotic Giant Branch Stars In M100., Sharon Meidt, Eva Schinnerer, Juan Carlos Munoz-Mateos, Benne W. Holwerda, Luis C. Ho, Barry F. Madore, Johan H. Knapen, Albert Bosma, E. Athanassoula, Joannah L. Hinz, Kartik Sheth, Michael Regan, Armando Gil De Paz, Karin Menendez-Delmestre, Mark Seibert, Taehyun Kim, Trisha Mizusawa, Dimitri A. Gadotti, Eija Laurikainen, Heikki Salo, Jarkko Laine, Sebastien Comeron
Faculty and Staff Scholarship
We examine the effect of circumstellar dust extinction on the near-IR (NIR) contribution of asymptotic giant branch (AGB) stars in intermediate-age clusters throughout the disk of M100. For our sample of 17 AGB-dominated clusters we extract optical-to-mid-IR spectral energy distributions (SEDs) and find that NIR brightness is coupled to the mid-IR dust emission in such a way that a significant reduction of AGB light, of up to 1 mag in the K band, follows from extinction by the dust shell formed during this stage. Since the dust optical depth varies with AGB chemistry (C-rich or O-rich), our results suggest that …
The Relationship Between Γ Cassiopeiae’S X-Ray Emission And Its Circumstellar Environment,
2012
Catholic University of America
The Relationship Between Γ Cassiopeiae’S X-Ray Emission And Its Circumstellar Environment, Myron A. Smith, Raimundo Lopes De Oliveira, Christian Motch, Gregory W. Henry, Noel D. Richardson, Karen S. Bjorkman, Philippe Stee, Denis Mourard, John D. Monnier, Xiao Che, R. Bücke, E. Pollmann, Douglas R. Gies, Gail Schaefer, Theo A. Ten Brummelaar, Harold Mcalister, Nils H. Turner, Judit Sturmann, Laszlo Sturmann, Stephen T. Ridgway
Information Systems and Engineering Management Research Publications
γ Cas is the prototypical classical Be star and is recently best known for its variable hard X-ray emission. To elucidate the reasons for this emission, we mounted a multiwavelength campaign in 2010 centered around four XMM-Newton observations. The observational techniques included long baseline optical interferometry (LBOI) from two instruments at CHARA, photometry carried out by an automated photometric telescope and Hα observations. Because γ Cas is also known to be in a binary, we measured radial velocities from the Hα line and redetermined its period as 203.55 ± 0.20 days and its eccentricity as near zero. The LBOI observations …
The Creation And Propagation Of Radiation: Fields Inside And Outside Of Sources,
2012
University of Texas at Brownsville
The Creation And Propagation Of Radiation: Fields Inside And Outside Of Sources, Stanislaw Olbert, John Belcher, Richard H. Price
Physics & Astronomy Faculty Publications
We present an algorithm for computing the electromagnetic fields due to currents inside and outside of finite sources with a high degree of spatial symmetry for arbitrary time-dependent currents. The solutions for these fields do not involve the time derivatives of the currents but involve only the currents and their time integrals. We give solutions for moving planar sheets of charge, and a rotating spherical shell carrying a uniform charge density. We show that the general solutions reduce to the standard expressions for magnetic dipole radiation for slow time variations of the currents. If the currents are turned on very …
The Curious Conundrum Regarding Sulfur Abundances In Planetary Nebulae,
2012
University of Oklahoma
The Curious Conundrum Regarding Sulfur Abundances In Planetary Nebulae, R. B. C. Henry, Angela Speck, Amanda I. Karakas, Gary J. Ferland, Mason Maguire
Physics and Astronomy Faculty Publications
Sulfur abundances derived from optical emission line measurements and ionization correction factors (ICFs) in planetary nebulae are systematically lower than expected for the objects' metallicities. We have carefully considered a large range of explanations for this "sulfur anomaly," including: (1) correlations between the size of the sulfur deficit and numerous nebular and central star properties, (2) ICFs which undercorrect for unobserved ions, (3) effects of dielectronic recombination on the sulfur ionization balance, (4) sequestering of S into dust and/or molecules, and (5) excessive destruction of S or production of O by asymptotic giant branch stars. It appears that all but …
Ensemble Forecasting Of Coronal Mass Ejections Using The Wsa-Enlil With Coned Model,
2012
Air Force Institute of Technology
Ensemble Forecasting Of Coronal Mass Ejections Using The Wsa-Enlil With Coned Model, Daniel J. Emmons Ii
Theses and Dissertations
The combination of the Wang-Sheeley-Arge (WSA) coronal model, ENLIL heliospherical model version 2.7, and Coned Model version 1.3 (WSA-ENLIL with Coned Model) was employed to form ensemble forecasts for 15 halo coronal mass ejections (CME's). The input parameter distributions were formed from 100 sets of CME cone parameters derived from the Coned Model. The Coned Model employed image processing along with the bootstrap approach to automatically calculate cone parameter distributions from SOHO-LASCO imagery based on techniques described by Pulkkinen et al. [2010]. The input parameter distributions were used as input to WSA-ENLIL to calculate the temporal evolution of the …
A Quantitative Analysis Of Solar Flare Characteristics As Observed In The Solar Observing Optical Network And The Global Oscillation Network Group,
2012
Air Force Institute of Technology
A Quantitative Analysis Of Solar Flare Characteristics As Observed In The Solar Observing Optical Network And The Global Oscillation Network Group, Thomas M. Wittman
Theses and Dissertations
This study consists of a quantitative comparison of H-alpha solar flare area and brightness as recorded by the Solar Observing Optical Network (SOON) and the Global Oscillation Network Group (GONG) from March 11 through November 30, 2011. The Air Force utilizes the three-site SOON network for H-alpha flare monitoring, while the six-site GONG network, managed by the National Solar Observatory, provides backup H alpha flare monitoring for SOON. A total of 1000 flares were observed and 100 of these were rated larger or brighter than the 0-F category. In the SOON network, 8% of flares observed by two sites had …
Hadamard Renormalisation Of The Stress Energy Tensor On The Horizons Of A Spherically Symmetric Black Hole Space-Time,
2012
Technological University Dublin
Hadamard Renormalisation Of The Stress Energy Tensor On The Horizons Of A Spherically Symmetric Black Hole Space-Time, Cormac Breen, Adrian Ottewill
Articles
We consider a quantum field which is in a Hartle-Hawking state propagating in a general spherically symmetric black hole space-time. We make use of uniform approximations to the radial equation to calculate the components of the stress tensor, renormalized using the Hadamard form of the Green's function, on the horizons of this space-time. We then specialize these results to the case of the `lukewarm' Reissner-Nordstrom-de Sitter black hole and derive some conditions on the stress tensor for the regularity of the Hartle-Hawking state
Third Component Search And Abundances Of The Very Dusty Short-Period Binary Bd +20°307,
2012
Tennessee State University
Third Component Search And Abundances Of The Very Dusty Short-Period Binary Bd +20°307, Francis C. Fekel, Maria J. Cordero, Raphael Galicher, Benjamin Zuckerman, Carl Melis, Alycia J. Weinberger
Information Systems and Engineering Management Research Publications
We have obtained near-infrared adaptive optics imaging and collected additional radial velocity observations to search for a third component in the extremely dusty short-period binary system BD +20°307. Our image shows no evidence for a third component at separations greater than 19 AU. Our four seasons of radial velocities have a constant center-of-mass velocity and are consistent with the systemic velocities determined at two earlier epochs. Thus, the radial velocities also provide no support for a third component. Unfortunately, the separation domains covered by our imaging and radial velocity results do not overlap. Thus, we examined the parameters for possible …
Non-Equilibrium Landauer Transport Model For Hawking Radiation From A Black Hole,
2012
University of Michigan
Non-Equilibrium Landauer Transport Model For Hawking Radiation From A Black Hole, P. D. Nation, M. P. Blencowe, Franco Nori
Dartmouth Scholarship
We propose that the Hawking radiation energy and entropy flow rates from a black hole can be viewed as a one-dimensional (1D), non-equilibrium Landauer transport process. Support for this viewpoint comes from previous calculations invoking conformal symmetry in the near-horizon region, which give radiation rates that are identical to those of a single 1D quantum channel connected to a thermal reservoir at the Hawking temperature. The Landauer approach shows in a direct way the particle statistics independence of the energy and entropy fluxes of a black hole radiating into vacuum, as well as one near thermal equilibrium with its environment. …
Ionized Reflection Spectra From Accretion Disks Illuminated By X-Ray Pulsars,
2012
Georgia Institute of Technology
Ionized Reflection Spectra From Accretion Disks Illuminated By X-Ray Pulsars, D. R. Ballantyne, J. D. Purvis, R. G. Strausbaugh, R. C. Hickox
Dartmouth Scholarship
X-ray reflection signatures are observed around multiple classes of accreting compact objects. Modelling these features yield important constraints on the physics of accretion disks, motivating the development of X-ray reflection models appropriate for a variety of systems and illumination conditions. Here, constant density ionized X-ray reflection models are presented for a disk irradiated with a very hard power-law X-ray spectrum (\Gamma < 1) and a variable high-energy cutoff. These models are then applied to the Suzaku data of the accreting X-ray pulsar LMC X-4, where very good fits are obtained with a highly ionized reflector responsible for both the broad Fe K line and the soft excess. The ionized reflector shows strong evidence for significant Doppler broadening and is redshifted by ~10^4 km/s. These features indicate that the reflecting material is associated with the complex dynamics occurring at the inner region of the magnetically-truncated accretion disk. Thus, reflection studies of X-ray pulsar spectra may give important insights into the accretion physics at the magnetospheric radius.
High-Resolution X-Ray Spectroscopy Reveals The Special Nature Of The Wolf-Rayet Star Winds.,
2012
University Potsdam
High-Resolution X-Ray Spectroscopy Reveals The Special Nature Of The Wolf-Rayet Star Winds., L. Oskinova, K. Gayley, W.-R. Hamann, D. Huenemoerder, Richard Ignace, A. Pollock
ETSU Faculty Works
We present the first high-resolution X-ray spectrum of a putatively single Wolf–Rayet (WR) star. 400 ks observations of WR 6 by the XMM-Newton telescope resulted in a superb quality high-resolution X-ray spectrum. Spectral analysis reveals that the X-rays originate far out in the stellar wind, more than 30 stellar radii from the photosphere, and thus outside the wind acceleration zone where the line-driving instability (LDI) could create shocks. The X-ray emitting plasma reaches temperatures up to 50 MK and is embedded within the unshocked, “cool” stellar wind as revealed by characteristic spectral signatures. We detect a fluorescent Fe line at …
The Kepler Light Curves Of V1504 Cygni And V344 Lyrae: A Study Of The Outburst Properties,
2012
University of Maryland - Baltimore County
The Kepler Light Curves Of V1504 Cygni And V344 Lyrae: A Study Of The Outburst Properties, John K. Cannizzo, Alan P. Smale, Matt A. Wood, Martin D. Still, Steve B. Howell
Aerospace, Physics, and Space Science Faculty Publications
We examine the Kepler light curves of V1504 Cyg and V344 Lyr, encompassing ~736 days at one-minute cadence. During this span each system exhibited ~64–65 outbursts, including 6 superoutbursts. We find that, in both systems, the normal outbursts lying between two superoutbursts increase in duration over time by a factor ~1.2–1.9, and then reset to a small value after the following superoutburst. In both systems the trend of quiescent intervals between normal outbursts is to increase to a local maximum about halfway through the supercycle—the interval from one superoutburst to the next—and then to decrease back to a small value …
Observed And Modeled Solar Cycle Variation In Geocoronal Hydrogen Using Nrlmsise-00 Thermosphere Conditions And The Bishop Analytic Exosphere Model,
2012
University of Wisconsin - Madison
Observed And Modeled Solar Cycle Variation In Geocoronal Hydrogen Using Nrlmsise-00 Thermosphere Conditions And The Bishop Analytic Exosphere Model, S. M. Nossal, E. J. Mierkiewicz, F. L. Roesler
Publications
High precision observations during Solar Cycle 23 using the Wisconsin H‐alpha Mapper (WHAM) Fabry‐Perot quantify a factor of 1.5 ± 0.15 higher Balmer α column emission intensity during near‐solar‐maximum than during solar minimum conditions. An unresolved question is how does the observed solar cycle variation in the hydrogen column emission compare with that calculated from the hydrogen distribution in atmospheric models? We have compared WHAM solar minimum and near‐solar‐maximum column intensity observations with calculations using the thermospheric hydrogen density profile and background thermospheric conditions from the Mass Spectrometer Incoherent Scatter (NRLMSISE‐00) empirical model extended to exospheric altitudes using the analytic …
Energetic Feedback And 26al From Massive Stars And Their Supernovae In The Carina Region,
2012
Department of Astrophysics/IMAPP, Radboud University Nijmegen
Energetic Feedback And 26al From Massive Stars And Their Supernovae In The Carina Region, R. Voss, P. Martin, R. Diehl, J. S. Vink, Dieter H. Hartmann, T. Preibisch
Publications
We study the populations of massive stars in the Carina region and their energetic feedback and ejection of 26Al. Methods. We did a census of the stellar populations in young stellar clusters within a few degrees of the Carina nebula. For each star we estimated the mass, based on the spectral type and the host cluster age. We used population synthesis to calculate the energetic feedback and ejection of 26Al from the winds of the massive stars and their supernova explosions. We used 7 years of INTEGRAL observations to measure the 26Al signal from the region. Results. The INTEGRAL 26Al …
Ion-By-Ion Cooling Efficiencies,
2012
California Institute of Technology
Ion-By-Ion Cooling Efficiencies, Orly Gnat, Gary J. Ferland
Physics and Astronomy Faculty Publications
We present ion-by-ion cooling efficiencies for low-density gas. We use Cloudy (version 10.00) to estimate the cooling efficiencies for each ion of the first 30 elements (H-Zn) individually. We present results for gas temperatures between 104 and 108 K, assuming low densities and optically thin conditions. When nonequilibrium ionization plays a significant role the ionization states deviate from those that obtain in collisional ionization equilibrium (CIE), and the local cooling efficiency at any given temperature depends on specific nonequilibrium ion fractions. The results presented here allow for an efficient estimate of the total cooling efficiency for any ionic …
Electron Microscopy Characterization Of Vanadium Dioxide Thin Films And Nanoparticles,
2012
Brigham Young University - Provo
Electron Microscopy Characterization Of Vanadium Dioxide Thin Films And Nanoparticles, Felipe Rivera
Theses and Dissertations
Vanadium dioxide (VO_2) is a material of particular interest due to its exhibited metal to insulator phase transition at 68°C that is accompanied by an abrupt and significant change in its electronic and optical properties. Since this material can exhibit a reversible drop in resistivity of up to five orders of magnitude and a reversible drop in infrared optical transmission of up to 80%, this material holds promise in several technological applications. Solid phase crystallization of VO_2 thin films was obtained by a post-deposition annealing process of a VO_{x,x approx 2} amorphous film sputtered on an amorphous silicon dioxide (SiO_2) …
