Astrophysics and Astronomy Commons^™

Orbits And Pulsations Of The Classical Ζ Aurigae Binaries, Joel A. Eaton, Gregory W. Henry, Andrew P. Odell

Information Systems and Engineering Management Research Publications

We have derived new orbits for ζ Aur, 32 Cyg, and 31 Cyg with observations from the Tennessee State University (TSU) Automatic Spectroscopic Telescope, and used them to identify nonorbital velocities of the cool supergiant components of these systems. We measure periods in those deviations, identify unexpected long-period changes in the radial velocities, and place upper limits on the rotation of these stars. These radial-velocity variations are not obviously consistent with radial pulsation theory, given what we know about the masses and sizes of the components. Our concurrent photometry detected the nonradial pulsations driven by tides (ellipsoidal variation) in both …

Synthesis And Characterization Of Type Ii Znse/Cds Core/Shell Nanocrystals, Alexander Nemchinov, Maria Kirsanova, Nishshanka N. Hewa-Kasakarage, Mikhail Zamkov

Physics and Astronomy Faculty Publications

High-quality ZnSe/CdS core/shell nanocrystals, exhibiting a type II carrier localization regime, were fabricated via a traditional pyrolysis of organometallic precursors. The two-step synthesis involved fabrication of 4.5-6 nm ZnSe seeds followed by a subsequent deposition of the CdS shell. An efficient spatial separation of electrons and holes between the core and the shell was observed for heterostructures containing more than three monolayers of CdS, which was primarily evidenced by the spatially indirect emission tunable from 480 to 610 nm for a fixed core diameter. Because of a large (type II) offset of band edges at the core/shell interface, fabricated nanocrystals …

Chandra Spectroscopy Of The Hot Star Β Crucis And The Discovery Of A Pre-Main-Sequence Companion, David H. Cohen, Michael Ascher Kuhn , '07, M. Gagné, Eric L.N. Jensen, N. A. Miller

Physics & Astronomy Faculty Works

In order to test the O star wind-shock scenario for X-ray production in less luminous stars with weaker winds, we made a pointed 74-ks observation of the nearby early B giant, beta Crucis (beta Cru; B0.5 III), with the Chandra High Energy Transmission Grating Spectrometer. We find that the X-ray spectrum is quite soft, with a dominant thermal component near 3 million K, and that the emission lines are resolved but quite narrow, with half widths of 150 km s(-1). The forbidden-to-intercombination line ratios of Ne IX and Mg XI indicate that the hot plasma is distributed in the wind, …

Flow Dynamics And Plasma Heating Of Spheromaks In Ssx, Michael R. Brown, C. D. Cothran, David H. Cohen, Jason Alexander Horwitz , '07, Vernon Hampden Chaplin , '07

Physics & Astronomy Faculty Works

We report several new experimental results related to flow dynamics and heating from single dipole-trapped spheromaks and spheromak merging studies at SSX. Single spheromaks (stabilized with a pair of external coils, see Brown, Phys. Plasmas 13 102503 (2006)) and merged FRC-like configurations (see Brown, Phys. Plasmas 13, 056503 (2006)) are trapped in our prolate (R = 0.2 m, L = 0.6 m) copper flux conserver. Local spheromak flow is studied with two Mach probes (r(1) = rho(i) ) calibrated by time-of-flight with a fast set of magnetic probes at the edge of the device. Both Mach probes feature six ion …

Initial Measurements Of Black Hole Spin In Gx 339-4 From Suzaku Spectroscopy, J. M. Miller, C. S. Reynolds, A. C. Fabian, E. M. Cackett, G. Miniutti, J. Raymond, D. Steeghs, R. Reis, J. Homan

Physics and Astronomy Faculty Research Publications

We report on a deep Suzaku observation of the stellar-mass black hole GX 339-4 in outburst. A clear, strong, relativistically shaped iron emission line from the inner accretion disk is observed. The broadband disk reflection spectrum revealed is one of the most sensitive yet obtained from an accreting black hole. We fit the Suzaku spectra with a physically motivated disk reflection model, blurred by a new relativistic line function in which the black hole spin parameter is a variable. This procedure yielded a black hole spin parameter of a=0.89+/-0.04. Joint modeling of these Suzaku spectra and prior XMM-Newton spectra obtained …

Optical Emissions Generated During Ionospheric Heating, Charles Kiumo Mutiso

Master's Theses - Daytona Beach

Ionospheric heating, accomplished by transmitting a high-frequency electromagnetic wave into the atmosphere, stimulates a large number of linear and non-linear wave-plasma interactions. One outcome of these interactions is the acceleration of thermal ionospheric electrons, leading to the production of induced optical emissions. Detection of these emissions yields information regarding wave-plasma interactions, which are of fundamental importance in many physical processes, and provides an effective means of remotely sensing ionospheric constituents and dynamics.

During an ionospheric heating experiment performed at the High Power Auroral Stimulation facility in Alaska (64.9° N, 146.8° W), a modified Czerny-Turner grating spectrometer acquired high resolution optical …

Book Review: Guide To Observing Deep-Sky Objects: A Complete Global Resource For Astronomers, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Guide to Observing Deep-Sky Objects : a Complete Global Resource for Astronomers by Jeff A. Farinacci. Springer, 2007 189p, 9780387728506 $29.95

Agn Dusty Tori. Ii. Observational Implications Of Clumpiness, Maia Nenkova, Matthew M. Sirocky, Robert Nikutta, Željko Ivezić, Moshe Elitzur

Physics and Astronomy Faculty Publications

Clumpy torus models with N₀ ~ 5–15 dusty clouds along radial equatorial rays successfully explain AGN infrared observations. The dust has standard Galactic composition, with individual cloud optical depth τ_V ~ 30–100 at visual. The models naturally explain the observed behavior of the 10 μm silicate feature, in particular the lack of deep absorption features in AGNs of any type, and can reproduce the weak emission feature tentatively detected in type 2 QSOs. The clouds' angular distribution must have a soft edge, e.g., Gaussian, and the radial distribution should decrease as 1/r or 1/r^{2 …}

Ages And Metallicities Of Early-Type Void Galaxies From Line Strength Measurements, Gary Wegner, Norman A. Grogin

Dartmouth Scholarship

We present spectroscopic observations of 26 galaxies of type E and S0, based on their blue morphologies, located in voids by the study of Grogin & Geller in 1999. Measurements of redshift, velocity dispersion, and four Lick line indices, Mg _b , Fe5270, Fe5335, and Hβ with their errors are given for all of these galaxies, along with Hβ, [O III], Hα, and [N II] emission line strengths for a subset of these objects. These sources are brighter than M* for low-density regions and tend to be bluer than their counterpart early-type objects in high-density regions. Using the models …

Observation Of Gamma-Ray Emission From The Galaxy M87 Above 250 Gev With Veritas, P. T. Reynolds, Et. Al.

Physical Sciences Publications

The multiwavelength observation of the nearby radio galaxy M87 provides a unique opportunity to study in detail processes occurring in active galactic nuclei from radio waves to TeV γ-rays. Here we report the detection of γ-ray emission above 250 GeV from M87 in spring 2007 with the VERITAS atmospheric Cerenkov telescope array and discuss its correlation with the X-ray emission. The γ-ray emission is measured to be pointlike with an intrinsic source radius less than 4.5'. The differential energy spectrum is fitted well by a power-law function: dΦ/dE = (7.4 ± 1.3stat ± 1.5sys)(E/TeV)(− 2.31 ± 0.17stat ± 0.2sys) 10−9 …

The Enigmatic Young Object: Walker 90/V590 Monocerotis, M. D. Joner, M. R. Perez, B. Mccollum, M. E. Van Dend Ancker

Faculty Publications

Aims. We assess the evolutionary status of the intriguing object Walker 90/V590 Mon, which is located about 20 arcmin northwest of the Cone Nebula near the center of the open cluster NGC 2264. This object, according to its most recent optical spectral type determination (B7), which we confirmed, is at least 3 mag too faint in V for the cluster distance, but it shows the classical signs of a young pre-main sequence object, such as highly variable H emission, Mg II emission, IR excess, UV continuum, and optical variability. Methods. We analyzed a collection of archival and original data on …

Large Scale Structure As A Probe Of Gravitational Slip, Scott F. Daniel, Robert R. Caldwell, Asantha Cooray, Alessandro Melchiorri

Dartmouth Scholarship

A new time-dependent, scale-independent parameter, ϖ, is employed in a phenomenological model of the deviation from general relativity in which the Newtonian and longitudinal gravitational potentials slip apart on cosmological scales as dark energy, assumed to be arising from a new theory of gravitation, appears to dominate the Universe. A comparison is presented between ϖ and other parametrized post-Friedmannian models in the literature. The effect of ϖ on the cosmic microwave background anisotropy spectrum, the growth of large-scale structure, the galaxy weak-lensing correlation function, and cross correlations of cosmic microwave background anisotropy with galaxy clustering are illustrated. Cosmological models with …

Abundances And Energy Spectra Of Corotating Interaction Region Heavy Ions Observed During Solar Cycle 23, Glenn M. Mason, Richard A. Leske, Mihir I. Desai, Christina M.S. Cohen, Joseph R. Dwyer, Joseph E. Mazur, Richard A. Mewaldt, Robert E. Gold, Stamatios M. Krimigis

Aerospace, Physics, and Space Science Faculty Publications

Using instruments on the ACE spacecraft, we surveyed the heavy-ion spectra and composition over the range He– Fe for 41 corotating interaction regions (CIRs) during 1998–2007. Below~ 1 MeV nucleon^-1 the spectra are power laws in kinetic energy nucleon^-1 with an average spectral index of 2:51 ± 0:10, rolling over above ~ 1 MeV nucleon^-1 to power-law spectra with an average index of 4:47 ± 0:17. The spectral shapes for different species are similar, leading to relative abundances that are constant over our energy range, even though the intensities cover up to 8 orders of magnitude. Relative to oxygen, the …

Silicates In Ultraluminous Infrared Galaxies, M. M. Sirocky, N. A. Levenson, Moshe Elitzur, H. W. W. Spoon, L. Armus

Physics and Astronomy Faculty Publications

We analyze the mid-infrared (MIR) spectra of ultraluminous infrared galaxies (ULIRGs) observed with the Spitzer Space Telescope's Infrared Spectrograph. Dust emission dominates the MIR spectra of ULIRGs, and the reprocessed radiation that emerges is independent of the underlying heating spectrum. Instead, the resulting emission depends sensitively on the geometric distribution of the dust, which we diagnose with comparisons of numerical simulations of radiative transfer. Quantifying the silicate emission and absorption features that appear near 10 and 18 μm requires a reliable determination of the continuum, and we demonstrate that including …

The First Mid-Infrared Spectra Of Cool White Dwarfs, Mukremin Kilic, Ted Von Hippel, Et Al.

Publications

We present the first mid-infrared spectra of two cool white dwarfs obtained with the Spitzer Space Telescope. We also present 3.5–8 μ m photometry for 19 cool white dwarfs with 5000 K ≤T_eff ≤ 9000 K. We perform a detailed model atmosphere analysis of these white dwarfs by fitting their UBVRIJHK and Spitzer photometry with state-of-the-art model atmospheres, and demonstrate that the optical and infrared spectral energy distributions of cool white dwarfs are well reproduced by our grid of models. Our mid-infrared photometry and 7.5-14.5 μm spectrum of WD 0018–267 are consistent with a T_eff = 5720 …

Geoeffectiveness Of Cir And Cme Events: Factors Contributing To Their Differences, L Laughlin, Niescja E. Turner

Physics and Astronomy Faculty Research

Recent work has shown that solar wind-magnetosphere coupling is more efficient for CIR-driven events than for CME-driven events. The study herein looks into the individual physical parameters of Corotating Interaction Regions (CIRs) and Coronal Mass Ejections (CMEs) and looks to isolate particular characteristics that leads to greater coupling of energy from the solar wind into the magnetosphere for certain classes of magnetic storms. While it is clear that these two types of events are distinct in their outcome, it is not known what in the nature of the events leads to these different results. The variation level in the z-component …

H I Line Profiles Of Galaxies: Tilted Ring Models, Erica Nelson

Pomona Senior Theses

Two-dimensional information on the kinematics and spatial distribution of gas in spiral galaxies is encoded in radio observations of their one-dimensional 21-cm neutral hydrogen (HI) line profiles. More than ten thousand HI profiles have been published and are publicly available. In order to explore the parameter space mapped out by the 21-cm neutral hydrogen line pro file, we have modified and run a FORTRAN-based computer simulation code. We have identified 7 control parameters that define the morphology of the modelled galaxy: they describe the neutral hydrogen gas distribution (density and spatial location of the gas), characteristics of its rotation curve, …

A Study Of Interacanding And Companion Galaxies: Implications For Cosmology, Kristen Petrillo

Pomona Senior Theses

This paper examined a few different types of interacting galaxies and the implications the data has on cosmological theories. An analysis of the Holmberg Effect, Holmberg (1969)’s observation that companion galaxies tend to be near the poles of edge-on galaxies rather than in the planes, was done by reexamining the spirals viewed by Holmberg. Only using radial velocity confirmed companions to test for this effect showed that if anything, the opposite of the Holmberg effect is true. However, due to small number statistics, more edge-on spirals and their companions would have to be viewed in order to determine if this …

The Rapidly Flaring Afterglow Of The Very Bright And Energetic Grb 070125, Adria C. Updike, Josh B. Haislip, Melissa C. Nysewander, Andrew S. Fruchter, D. Alexander Kann, Sylvio Klose, Peter A. Milne, G. Grant Williams, Weikang Zheng, Carl W. Hergenrother, Jason X. Prochaska, Jules P. Halpern, Nestor Mirabal, John R. Thorstensen

Dartmouth Scholarship

We report on multiwavelength observations, ranging from X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implying a likely redshift of z = 1.547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of ~7.0°, and implying an intrinsic GRB energy in the 1-10,000 keV band of around E_γ = (6.3–6.9) × 10⁵¹ ergs (based on the fluences measured by …

Shaping Graphene: An Alternative Approach, Ian W. Frank

Pomona Senior Theses

With experimentation on graphene (an atomic layer of graphite) becoming more and more common it is imperative that we have the capability to shape the material beyond the random manner in which it is deposited by mechanical exfoliation. This capability would be invaluable not only for the interesting electronic and optical properties that can be obtained, but also potentially for characterizing the mechanical resonators that we have been able to fabricate here at Pomona College by suspending few-layer graphene sheets over trenches in SiO2. We propose novel methods for etching graphene that should allow us to shape the material when …

Deep Advanced Camera For Surveys Imaging In The Globular Cluster Ngc 6397: The Cluster Color-Magnitude Diagram And Luminosity Function, Harvey B. Richer, Aaron Dotter, Jarrod Hurley, Jay Anderson

Dartmouth Scholarship

We present the color-magnitude diagram (CMD) from deep Hubble Space Telescope imaging in the globular cluster NGC 6397. The Advanced Camera for Surveys (ACS) was used for 126 orbits to image a single field in two colors (F814W, F606W) 5' SE of the cluster center. The field observed overlaps that of archival WFPC2 data from 1994 and 1997 which were used to proper motion (PM) clean the data. Applying the PM corrections produces a remarkably clean CMD which reveals a number of features never seen before in a globular cluster CMD. In our field, the main-sequence stars appeared to terminate …

A Joint Search For Gravitational Wave Bursts With Auriga And Ligo, L. Baggio, M. Bignotto, M. Bonaldi, M. Cerdonio, M. De Rosa, P. Falferi, S. Fattori, P. Fortini, G. Giusfredi, M. Inguscio, N. Liguori, S. Longo, F. Marin, R. Mezzena, A. Mion, A. Ortolan, S. Poggi, G. A. Prodi, V. Re, F. Salemi, G. Soranzo, L. Taffarello, G. Vedovato, A. Vinante, S. Vitale, J. P. Zendri, B. Abbott, R. Abbott, R. Adhikari, J. Agresti, P. Ajith, Tiffany Z. Summerscales

Faculty Publications

The first simultaneous operation of the AURIGA detector and the LIGO observatory was an opportunity to explore real data, joint analysis methods between two very different types of gravitational wave detectors: resonant bars and interferometers. This paper describes a coincident gravitational wave burst search, where data from the LIGO interferometers are cross-correlated at the time of AURIGA candidate events to identify coincident transients. The analysis pipeline is tuned with two thresholds, on the signal-to-noise ratio of AURIGA candidate events and on the significance of the cross-correlation test in LIGO. The false alarm rate is estimated by introducing time shifts between …

The Chromospherically Active, Triple, Ellipsoidal, And Eclipsing Binary Hd 6286 = Be Piscium: A Laboratory For Binary Evolution, Klaus G. Strassmeier, János Bartus, Francis C. Fekel, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Aims. We present a detailed analysis of the star HD 6286 = BE Psc from 16 years of spectroscopic observations and 18 seasons of photometric ones. The star is an evolved, chromospherically active, eclipsing binary, consisting of a K1 giant plus an F6 dwarf/subgiant in a circular orbit with a period of 35.671 days. A faint, close visual companion of spectral type ≈G0 makes the system triple. The orbital inclination of the eclipsing pair is 818.

Methods. We have obtained simultaneous solutions with our extensive set of radial velocities and light curves that include the star spot variability of …

Foundations And Interpretations Of Quantum Mechanics, Cory Johnson

Honors Theses

The first famous thought experiment of Einstein gives rise to his theories of relativity, the bedrock of modern astrophysics and cosmology. His second famous thought experiment begins the investigation into the foundations of quantum mechanics. It leads to a paradox, inspiring various 'no-go' theorems proven by Bell, Kochen, and Specker. Physicists and philosophers worldwide become increasingly dissatisfied with the probabilistic complementarity interpretation (Born-Bohr) and eventually offer their own accounts of the theory. By the end of the 20th century two alternative approaches stand out as the best candidates: Both the hidden variables interpretation (de Broglie-Bohm) and the many worlds interpretation …

Effects Of Context Of Natural And Artifactual Objects On Categorization, Linsey Walker

Honors Theses

Categorization of animals and vehicles in different contexts was investigated in three experiments using event related potentials (ERPs). The presence of a background and congruency of the background in relation to the object were both manipulated in order to determine the effects of context on visual processing. In Experiment 1, adults were presented with images of animals and vehicles in two conditions: situated in a congruent context (e.g. an animal in a field) and in the absence of a context (an animal in a white homogeneous background). In experiment 2, adults were presented with images of animals and vehicles in …

A Timer Module For An 8051 Microcontroller, Troy England

Electrical Engineering Undergraduate Honors Theses

A timer module for an 8051 Microcontroller is designed from the ground up. It could potentially be integrated into a larger 8051 for use in lunar and Martian missions. It follows through a synchronous digital design flow from HDL code through layout verification. The timer shows functionality at 100MHz with some minor glitches.

The Transport Of Cosmic Rays In Self‐Excited Magnetic Turbulence, Brian Reville, Stephen O'Sullivan, Peter Duffy, John Kirk

Articles

The process of diffusive shock acceleration relies on the efficacy with which hydromagnetic waves can scatter charged particles in the precursor of a shock. The growth of self-generated waves is driven by both resonant and non-resonant processes. We perform high-resolution magnetohydrodynamic simulations of the non-resonant cosmic ray driven instability, in which the unstable waves are excited beyond the linear regime. In a snapshot of the resultant field, particle transport simulations are carried out. The use of a static snapshot of the field is reasonable given that the Larmor period for particles is typically very short relative to the instability growth …

On The Steering Of Sound Energy Through A Supercritical Plate By A Near-Field Transducer Array, Brian E. Anderson, Stephen A. Hambric, Jack W. Hughes

Faculty Publications

The ability to direct sound energy through the flexural vibrations of a submerged plate at various angles of incidence using a near-field transducer array is investigated. An alumina bar is placed in front of a one-dimensional, eight-element transducer array, between the array and the water. Operating in a receive mode, data were taken as a function of angle of incidence and compared to data taken without the presence of the alumina bar. The array was also operated in transmit mode and results were compared to corresponding receive mode data, showing that reciprocity holds. Results show that in fact sound energy …

Host Galaxy Extinction Of Type Ia Supernovae : Co-Evolution Of Interstellar Medium Structure And The Extinction Law With Star Formation., Benne W. Holwerda

Faculty and Staff Scholarship

This paper presents a mechanism that may modify the extinction law for Type Ia supernovae (SNeIa) observed at higher redshift. Starting from the observations that (i) SNeIa occur predominantly in spiral galaxies, (ii) star formation ejects interstellar medium (ISM) out of the plane of spirals, (iii) star formation alters the extinction properties of the dust in the ISM, and (iv) there is substantially more star formation at higher redshift, I propose that spiral galaxies have a dustier halo in the past than they do now. The ejected material’s lower value of RV will lead to a lower average value (R¯ …

Determining The Temperature Of Exoplanet Hat-P-1b, Kamen O. Todorov

Physics, Astronomy and Geophysics Honors Papers

Exoplanets, or planets orbiting stars other than our Sun, are difficult to detect. It is even more difficult to determine their properties. In this thesis I focus on HAT-P-1b, which is a ¨Dhot Jupiter¡¬ ¨C a gas giant, extremely close to its parent star. It is important for this thesis that HAT-P-1b is also a transiting exoplanet, i.e., it periodically passes directly in front of, or behind, its parent star, which gives scientists unique opportunities to determine its physical properties, to measure its temperature and to study its atmosphere¡¯s chemical properties. The purpose of this thesis is to measure the …