Astrophysics and Astronomy Commons^™

Spectroscopy And Photometry Of Cataclysmic Variable Candidates From The Catalina Real Time Survey, John R. Thorstensen, Julie N. Skinner

Dartmouth Scholarship

The Catalina Real Time Survey (CRTS) has found over 500 cataclysmic variable (CV) candidates, most of which were previously unknown. We report here on follow-up spectroscopy of 36 of the brighter objects. Nearly all of the spectra are typical of CVs at minimum light. One object appears to be a flare star, while another has a spectrum consistent with a CV but lies, intriguingly, at the center of a small nebulosity. We measured orbital periods for eight of the CVs, and estimated distances for two based on the spectra of their secondary stars. In addition to the spectra, we obtained …

The Characterization Of Virgo Data And Its Impact On Gravitational-Wave Searches, J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. D. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, P. Addesso, R. Adhikari, C. Affeldt, M. Agathos, K. Agatsuma, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, S. Ast, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert, B. E. Aylott, Tiffany Z. Summerscales

Faculty Publications

Between 2007 and 2010 Virgo collected data in coincidence with the LIGO and GEO gravitational-wave (GW) detectors. These data have been searched for GWs emitted by cataclysmic phenomena in the universe, by non-axisymmetric rotating neutron stars or from a stochastic background in the frequency band of the detectors. The sensitivity of GW searches is limited by noise produced by the detector or its environment. It is therefore crucial to characterize the various noise sources in a GW detector. This paper reviews the Virgo detector noise sources, noise propagation, and conversion mechanisms which were identified in the three first Virgo observing …

Spectro-Interferometric Observations Of Classical Nova V458 Vul 2007, Samira Rajabi, Matthew W. Muterspaugh, Benjamin F. Lane, Martin M. Sirk, Stanley Browne, Askari Ghasempour, Samuel P. Halverson, John G. Kelly, Michael Williamson

Information Systems and Engineering Management Research Publications

We used the Palomar Testbed Interferometer (PTI) to resolve 2.2 μm emission from the classical nova V458 Vul 2007 over the course of several days following its discovery on 2007 August 8.54 UT. We also obtained K-band photometric data and spectra of the nova during the early days of the outburst. We also used photometric measurements from the AAVSO database. This is a unique data set offering a three-technique approach: high-resolution imaging, spectroscopy, and photometry. Our analysis shows that the nova ejecta can be modeled as an inclined disk at low inclination, i.e., low ellipticity which is consistent with the …

Quantum Dynamics Using Lie Algebras, With Explorations In The Chaotic Behavior Of Oscillators, Ryan Thomas Sayer

Theses and Dissertations

We study the time evolution of driven quantum systems using analytic, algebraic, and numerical methods. First, we obtain analytic solutions for driven free and oscillator systems by shifting the coordinate and phase of the undriven wave function. We also factorize the quantum evolution operator using the generators of the Lie algebra comprising the Hamiltonian. We obtain coupled ODE's for the time evolution of the Lie algebra parameters. These parameters allow us to find physical properties of oscillator dynamics. In particular we find phase-space trajectories and transition probabilities. We then search for chaotic behavior in the Lie algebra parameters as a …

Further Evidence For Large Central Mass-To-Light Ratios In Early-Type Galaxies: The Case Of Ellipticals And Lenticulars In The A262 Cluster, G. A. Wegner, E. M. Corsini, J. Thomas, R. P. Saglia

Dartmouth Scholarship

We present new radially resolved spectroscopy of eight early-type galaxies in the A262 cluster. The measurements include stellar rotation, velocity dispersion, H ₃ and H ₄ coefficients of the line-of-sight velocity distribution along the major and minor axes and an intermediate axis as well as line-strength index profiles of Mg, Fe, and Hβ. The ionized-gas velocity and velocity dispersion is measured for six sample galaxies along different axes. We derive dynamical mass-to-light ratios and dark matter densities from orbit-based dynamical models, complemented by the galaxies' ages, metallicities, and α-element abundances from single stellar-population models. The ionized-gas kinematics give a valuable …

The Reaction Of Methane With Platinum Oxide Nanoclusters: A Computational Study, Dane Stewart

Symposium on Research and Creative Expression (SORCE)

Previous studies have shown that small clusters of transition metals like Pt, when reacted with oxygen, have useful catalytic properties compared to thin-film or bulk catalysts. These clusters have the potential for use in developing cheaper methods for converting propane to propene, which is a high-value compound used in making plastics. Understanding the structure and formation of these clusters is essential to gauging how reactive each catalyst is. Computational studies of Pt4O2 are being done using Gaussian 03 to understand their formation, and determine the stability of different spin states. The effectiveness of these clusters is then being tested using …

Studying The Variability Of Dying Stars, Austin Bain, Hannah Rotter, Aaron Seider

Symposium on Research and Creative Expression (SORCE)

In this project, we are observing and analyzing the light variability in a class of dying stars. This involves observing then on clear nights, primarily at the Valparaiso University Observatory but also including a few nights at the SARA Telescope at Kitt Peak National Observatory in Arizona. Thus far this summer we have observed for 25 nights and we observed 31 stars. Some of them we observed on every clear night and others we observed once or twice a week. We are analyzing a subset of 18 of these. We find that they have varied in light by 12 to …

Performance Studies Of The Forward Gem Tracker, Malorie Stowe

Symposium on Research and Creative Expression (SORCE)

The spin of the proton is thought to be produced by several constituents including quarks, antiquarks, and gluons. It has been the goal of STAR (Solenoidal Tracker at RHIC) to measure the contribution of gluons and various sea quarks to the proton spin. The Forward GEM Tracker (FGT) is a detector in STAR, which is located at the RHIC (Relativistic Heavy Ion Collider) collider at Brookhaven National Laboratory. The FGT serves to track the position of forward-going charged particles, and it will be instrumental in observing the decay leptons from W bosons created by the interaction of the quark of …

Finding Variable Stars In Planetary Nebulae Using The Isis Image Subtraction Software, Jake Long, Kevin Nault

Symposium on Research and Creative Expression (SORCE)

Planetary nebulae are a brief and often spectacular stage in the life of stars like the sun during which the star expels its outer layers into space. In order to explain the great variety of observed shapes among planetary nebulae, we are examining the theory that binary central stars of planetary nebulae are a significant factor in their shaping. We determine if the central star of planetary nebulae is binary by looking for photometric periodic variability, a common feature of close binary systems. Using existing data we evaluate the variability using a computer program called ISIS. We have seen the …

Neutral Pion Background Analysis At Star, Adam Clark

Symposium on Research and Creative Expression (SORCE)

The STAR detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory takes measurements of cross section and spin observables of polarized proton collisions. The Endcap Electromagnetic Calorimeter (EEMC) allows measurements of electromagnetic particles in the forward direction, 1 < η < 2. The EEMC detector will be used to measure the neutral pion (π⁰) double longitudinal spin asymmetry which gives us information about the gluon contribution to the proton's spin. The π⁰ cross section is an important measurement to verify our signal reconstruction and the background characterization. In order to measure the π⁰ cross section and asymmetry, the backgrounds must be identified (such as those from photon conversions and …

Neutron Electric Dipole Moment: Research And Development, Benjamin Barber

Symposium on Research and Creative Expression (SORCE)

The neutron's electric dipole moment (nEDM) serves as an important test of the Standard Model of particle physics and it's various alternatives. Various models of fundamental physics allow for different magnitudes for the nEDM, and recent experiments have begun to exclude some models. Valparaiso University is part of a collaboration of institutions working on an improved experiment to measure the nEDM, to be conducted at Oak Ridge National Laboratory in the next few years. The experiment will be performed at 0.4 Kelvin, and will involve the use of magnetic fields and very large electric fields. Research at Los Alamos National …

Confronting A Solar Irradiance Reconstruction With Solar And Stellar Data, Philip G. Judge, G. Wesley Lockwood, Richard R. Radick, Gregory W. Henry, Alexander I. Shapiro, Werner Schmutz, Charles Lindsey

Information Systems and Engineering Management Research Publications

Context. A recent paper by Shapiro and colleagues (2011, A&A, 529, A67) reconstructs spectral and total irradiance variations of the Sun during the holocene.

Aims. In this note, we comment on why their methodology leads to large (0.5%) variations in the solar TSI on century-long time scales, in stark contrast to other reconstructions which have ≲ 0.1% variations.

Methods. We examine the amplitude of the irradiance variations from the point of view of both solar and stellar data.

Results. Shapiro et al.’s large amplitudes arise from differences between the irradiances computed from models A and C of Fontenla and colleagues, …

The Implementation Of The Shear Correlation Function And The Matter Power Spectrum In R, Allison A. Scheppelmann, Deborah J. Bard

STAR Program Research Presentations

Weak gravitational lensing is an important tool in understanding the large-scale structure of the universe. One component in understanding the effect of weak gravitational lensing is the shear correlation function and matter power spectrum. The calculation of these values is often complicated and time consuming. In order to decrease the cost of these calculations they were implemented in R using parallelization. This resulted in the calculations completing faster and the process to be easily changed in order to fit the need of each researcher using the algorithms created in R.

Electric Currents Due To Stress-Activated Positive Hole Charge Carriers In Ice, Cary T. Keller P.E., Friedemann T. Freund, Dale P. Cruikshank

STAR Program Research Presentations

Jupiter’s satellite Europa, whose surface is composed of ice with a possible water ocean beneath, could conceivably serve as an abode for extraterrestrial life. This and other icy celestial bodies may contain organic macromolecular solid material that is produced when surface ices are exposed to ultraviolet radiation and/or electrical energy. Tidal and tectonic stresses or meteorite impacts in icy crusts may produce electrical discharges, which would provide the energy for in-situ synthesis of the organic solids. This electrical energy can be provided by positive hole charge carrier activation. Positive holes exhibit properties such as the ability to flow out of …

Telescope Assembly Alignment Simulator Performance Optimization, Joshua G. Thompson, Brian Eney, Zaheer Ali, Bob Thompson

STAR Program Research Presentations

The Telescope Assembly Alignment Simulator (TAAS) calibrates scientific instruments (SI’s) that are installed on the Stratospheric Observatory For Infrared Astronomy (SOFIA). An SI’s accuracy is directly dependent on the consistent performance of the TAAS, which has never been fully characterized. After designing various thermal and optical experiments to identify the current unknowns of TAAS, we now have a far better grasp on how the equipment behaves.

A Comparison Of Broad Iron Emission Lines In Archival Data Of Neutron Star Low-Mass X-Ray Binaries, Edward M. Cackett, Jon M. Miller, Rubens C. Reis, Andrew C. Fabian, Didier Barret

Physics and Astronomy Faculty Research Publications

Relativistic X-ray disklines have been found in multiple neutron star low-mass X-ray binaries, in close analogy with black holes across the mass scale. These lines have tremendous diagnostic power and have been used to constrain stellar radii and magnetic fields, often finding values that are consistent with independent timing techniques. Here, we compare CCD-based data from Suzaku with Fe K line profiles from archival data taken with gas-based spectrometers. In general, we find good consistency between the gas-based line profiles from EXOSAT, BeppoSAX, and RXTE and the CCD data from Suzaku, demonstrating that the broad profiles seen are intrinsic to …

Nasa Flight Opportunities Program (Fop) Platform Tradeoffs Analysis, Stephanie Kugler, Dougal Maclise

STAR Program Research Presentations

The Flight Opportunities Program (FOP) exemplifies NASA’s shift in policy from a public driven space industry towards an emphasis on public-private partnerships. The Payloads team, as part of FOP, is responsible for soliciting, selecting and shepherding payloads that require flight testing in order to mature technologies, not only to reduce risk in a deep space or manned space missions, but also to develop critical technologies with multiple applications in space. Several companies have been awarded contracts to provide these flight opportunities and each have unique capabilities to fly payloads in environments that closely imitate the environment of space missions. As …

Leds And Astronomy, Britny N. Delp, Stephen M. Pompea

STAR Program Research Presentations

Using a Czerny-Turner spectrometer, 45 different types of outdoor lights were categorized. These spectra were used to determine how useful the light is to human eyes and how dark skies friendly these lights are. Dark skies friendly lighting means that little to no light shines above a right angle to the light, and should emit as little as possible below 500nm (green) wavelengths. The short wavelengths present a problem to astronomers in the form of Rayleigh scattering. The following criterion were used in selecting the best source for urban and rural lighting: color rendition measured by color rendering index (CRI), …

Effect Of Particle Statistics In Strongly Correlated Two-Dimensional Hubbard Models, Ehsan Khatami, Marcos Rigol

Faculty Publications

We study the onset of particle statistics effects as the temperature is lowered in strongly correlated two-dimensional Hubbard models. We utilize numerical linked-cluster expansions and focus on the properties of interacting lattice fermions and two-component hard-core bosons. In the weak-coupling regime, where the ground state of the bosonic system is a superfluid, the thermodynamic properties of the two systems at half filling exhibit very large differences even at high temperatures. In the strong-coupling regime, where the low-temperature behavior is governed by a Mott insulator for either particle statistics, the agreement between the thermodynamic properties of both systems extends to regions …

Student-Teacher Interactions For Bringing Out Student Ideas About Energy, Benedikt W. Harrer, Michael Wittmann, Rachel Scherr

Faculty Publications

Modern middle school science curricula use group activities to help students express their thinking and enable them to work together like scientists. We are studying rural 8th grade science classrooms using materials on energy. Even after spending several months with the same curriculum on other physics topics, students' engagement in group activities seems to be restricted to creating lists of words that are associated with energy. Though research suggests that children have rich and potentially valuable ideas about energy, our students don't seem to spontaneously use and express their ideas in the classroom. Only within or after certain interactions with …