Astrophysics and Astronomy Commons^™

The Opacity Of Spiral Galaxy Disks. Iii. Automating The Synthetic Field Method., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. Van Der Kruit

Faculty and Staff Scholarship

Dust extinction in spiral disks can be estimated from the counts of background field galaxies, provided the deleterious effects of confusion introduced by structure in the image of the foreground spiral disk can be calibrated. Gonzalez et al. developed a method for this calibration, the Synthetic Field Method (SFM), and applied this concept to a Hubble Space Telescope (HST )/Wide Field Planetary Camera 2 image of NGC 4536. The SFM estimates the total extinction through the disk without requiring assumptions about the distribution of absorbers or disk light. The poor statistics, however, result in large errors in individual measurements. We …

The Opacity Of Spiral Galaxy Disks. Iv. Radial Extinction Profiles From Counts Of Distant Galaxies Seen Through Foreground Disks., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. Van Der Kruit

Faculty and Staff Scholarship

Dust extinction can be determined from the number of distant field galaxies seen through a spiral disk. To calibrate this number for the crowding and confusion introduced by the foreground image, Gonzalez et al. and Holwerda et al. developed the Synthetic Field Method (SFM ), which analyzes synthetic fields constructed by adding various deep exposures of unobstructed background fields to the candidate foreground galaxy field. The advantage of the SFM is that it gives the average opacity for the area of a galaxy disk without making assumptions about either the distribution of absorbers or of the disk starlight. However, it …

Book Review: The New Amateur Astronomer, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The New Amateur Astronomer by Martin Mobberley. Springer, 2004 229p, 1852336633 $34.95

The Use Of X-Ray Pulsars For Aiding Gps Satellite Orbit Determination, Dennis W. Woodfork Ii

Theses and Dissertations

This research proposes the use of an existing "signal of opportunity" - namely x-ray pulsars - to improve the accuracy and robustness of the GPS satellite and clock estimation algorithm. Improvement in satellite and clock accuracy results in a direct benefit to the user. A simulation has been developed to determine the effects of using x-ray pulsar measurements on the GPS Operational Control Segment. The epoch-specific position, velocity, and clock errors of all GPS satellites in the constellation were estimated using both pseudoranges and time-difference-of-arrival (TDOA) measurements from pulsars. The primary measure of accuracy is a constellation Signal-In-Space Range Error …

Optical Detection Of Ultracold Neutral Calcium Plasmas, Elizabeth Ann Cummings

Theses and Dissertations

We demonstrate an optical method to detect calcium ions in an ultracold plasma. We probe the plasma with a 397 nm laser beam tuned to a calcium ion transition. The probe laser beam is focused to a 160 µm waist allowing fine spatial resolution. Ions are detected by measuring fluorescence using a Photo-Multiplier Tube (PMT). The signal, an average of 4000 acquisitions, has a temporal resolution of 120 ns. We present the details of this method, potential improvements, and prospects of imaging the expanding plasma ions. We also present preliminary work on spatially resolved absorption measurements, as well as additional …

Long Period Variables In The Globular Cluster 47 Tuc: Radial Velocity Variations, Thomas Lebzelter, Peter R. Wood, Kenneth H. Hinkle, Richard R. Joyce, Francis C. Fekel

Information Systems and Engineering Management Research Publications

We present near infrared velocity curves for 12 long period variables (LPVs) in the globular cluster 47 Tuc (NGC 104). New light curves are also presented for these variables. Results are compared with the period-luminosity sequences occupied by the LPVs in the LMC. Sequence C variables (fundamental mode pulsators) have larger velocity amplitudes than sequence B variables (first overtone pulsators). We show that, at similar luminosities, higher mass loss rates are associated with larger pulsation amplitudes. One variable (V18) does not fit the normal period luminosity sequences and it has an unusually large amount of circumstellar dust, suggesting that it …

The Chromospheric Activity And Ages Of M Dwarf Stars In Wide Binary Systems, Nicole M. Silvesteri, T. D. Oswalt, Suzanne L. Hawley

Publications

We investigate the relationship between age and chromospheric activity for 139 M dwarf stars in wide binary systems with white dwarf companions. The age of each system is determined from the cooling age of its white dwarf component. The current limit for activity-age relations found for M dwarfs in open clusters is 4 Gyr. Our unique approach to finding ages for M stars allows for the exploration of this relationship at ages older than 4 Gyr. The general trend of stars remaining active for a longer time at later spectral type is confirmed. However, our larger sample and greater age …

The N2k Consortium. I. A Hot Saturn Planet Orbiting Hd 88133, Debra A. Fischer, Gregory Laughlin, Paul Butler, Geoff W. Marcy, John Johnson, Greg Henry, Jeff Valenti, Steve Vogt, Mark Ammons, Sarah Robinson, Greg Spear, Jay Strader, Peter Driscoll, Abby Fuller, Teresa Johnson, Elizabeth Manrao, Chris Mccarthy, Melesio Muñoz, Kok Leong Tah, Jason Wright, Shigeru Ida, Bun'ei Sato, Eri Toyota, Dante Minniti

Information Systems and Engineering Management Research Publications

The N2K ("next 2000") consortium is carrying out a distributed observing campaign with the Keck, Magellan, and Subaru telescopes, as well as the automatic photometric telescopes of Fairborn Observatory, in order to search for short-period gas giant planets around metal-rich stars. We have established a reservoir of more than 14,000 main-sequence and subgiant stars closer than 110 pc, brighter than V = 10.5, and with 0.4 < B - V < 1.2. Because the fraction of stars with planets is a sensitive function of stellar metallicity, a broadband photometric calibration has been developed to identify a subset of 2000 stars with [Fe/H] > 0.1 dex for this survey. We outline the strategy and report the detection of a planet orbiting the metal-rich G5 IV star HD 88133 with a period of 3.41 days, semivelocity amplitude K = …

A Study Of Bright Southern Long Period Variables, Thomas Lebzelter, Kenneth H. Hinkle, Peter R. Wood, Richard R. Joyce, Francis C. Fekel

Information Systems and Engineering Management Research Publications

In this paper we present radial velocity curves of AGB variables that exhibit various kinds of anomalies: semiregular variables (SRVs) with typical mira periods, SRVs exceeding the mira 2.5 mag amplitude limit, miras with secondary maxima in their light curves, and a SRV with a long secondary period. The stars with reliable Hipparcos parallaxes from this and from previous studies are plotted in a -diagram. Our objects nicely follow the -relations determined for the LMC. This allows the pulsation mode to be identified. While all miras fall on the fundamental mode sequence, the SRVs fall on both the first overtone …

Hd 166181 = V815 Herculis, A Single-Lined Spectroscopic Multiple System, Francis C. Fekel, David J. Barlow, Colin D. Scarfe, Sylvie Jancart, Dimitri Pourbaix

Information Systems and Engineering Management Research Publications

We have obtained extensive spectroscopic and velocity spectrometer observations of HD 166181, a previously known single-lined spectroscopic binary. Our improved orbit for the G6 V primary has a period of 1.8098343 days and is circular. Although the lines of additional components have not been detected, radial velocity measurements confirm that the system has additional velocity variations with a period of 2092 days, or 5.73 yr. This long-period orbit has an eccentricity of 0.76. An analysis of the Hipparcos observations produces a well-determined astrometric orbit for the long-period system that has an inclination of 78°. Mass estimates of the components in …

X-Ray Variability During The Quiescent State Of The Neutron Star X-Ray Transient In The Globular Cluster Ngc 6440, Edward M. Cackett, Rudy Wijnands, Craig O. Heinke, Peter D. Edmonds, Walter H. G. Lewin, David Pooley, Jonathan E. Grindlay, Peter G. Jonker, Jon M. Miller

Physics and Astronomy Faculty Research Publications

The globular cluster NGC 6440 is known to harbor a bright neutron star X-ray transient. We observed the globular cluster with Chandra on two occasions when the bright transient was in its quiescent state, in 2000 July and 2003 June (both observations were made nearly 2 yr after the end of their preceding outbursts). The quiescent spectrum during the first observation is well represented by a two-component model (a neutron star atmosphere model plus a power-law component that dominates at energies above 2 keV). During the second observation (which was roughly of equal duration to the first observation) we found …

Art Of The Astrolabe, Heather Suzanne Campbell

Archived Theses and Dissertations

The astrolabe is a well known scientific instrument, commonly found in Islamic art collections. Despite its placement in art museums, it does not receive the same examination or discussion as other metalwork. This leads to errors in dating and place of origin when an instrument that lacks a dedication inscription or a signature.

This study places the astrolabe in an art historical context and not a scientific one.

Much literature has been written on this instrument concentrating on the scientific nature of the instrument or as part of a collection of scientific instruments. Its history, function, place in society and …

Five New Extrasolar Planets, Geoffrey W. Marcy, R. Paul Butler, Steve Vogt, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, Jason T. Wright, John A. Johnson

Information Systems and Engineering Management Research Publications

We report multiple Doppler measurements of five nearby FGK main-sequence stars and subgiants obtained during the past 4-6 yr at the Keck Observatory. These stars, namely, HD 183263, HD 117207, HD 188015, HD 45350, and HD 99492, all exhibit coherent variations in their Doppler shifts consistent with a planet in Keplerian motion. The five new planets occupy known realms of planetary parameter space, including a wide range of orbital eccentricities, e = 0-0.78, and semimajor axes, 0.1-3.8 AU, that provide further statistical information about the true distributions of various properties of planetary systems. One of the planets, HD 99492b, has …

Optical Spectroscopy Of The Surface Population Of The Ρ Ophiuchi Molecular Cloud: The First Wave Of Star Formation, Bruce Wilking, Michael Meyer, John Robinson, Thomas Greene

Physics Faculty Works

We present the results of optical spectroscopy of 139 stars obtained with the Hydra multiobject spectrograph. The objects extend over a 1.3 deg2 area surrounding the main cloud of the ρ Oph complex. The objects were selected from narrowband images to have Hα in emission. Using the presence of strong Hα emission, lithium absorption, location in the Hertzsprung-Russell diagram, or previously reported X-ray emission, we were able to identify 88 objects as young stars associated with the cloud. Strong Hα emission was confirmed in 39 objects with line widths consistent with their origin in magnetospheric accretion columns. Two of the …

Ultrarelativistic Plasma Shell Collisions In Γ‐Ray Burst Sources: Dimensional Effects On The Final Steady State Magnetic Field, C. H. Jaroschek, H. Lesch, R. A. Treumann

Dartmouth Scholarship

Ultrarelativistic electron-positron plasma shell collisions as an integral part of generic γ-ray burst (GRB) fireball models are studied in the framework of self-consistent three-dimensional particle-in-cell simulations. We compare scenarios at moderately relativistic (γ₀ 10) and ultrarelativistic (γ₀ 100) energies that directly correspond to the regimes of internal and external shell collisions, respectively, in GRB synchrotron emission models. Simulated systems comprise 5 × 10⁸ particles, applying a relativistic, fully electromagnetic, massively parallelized code. It is found that Weibel-generated, steady state magnetic equipartition ratios in external collisions reach up to _B ~ 12%, exceeding the respective internal ratios by …

Mass-To-Light Ratio Gradients In Early-Type Galaxy Haloes, N. R. Napolitano, M. Capaccioli, Aaron J. Romanowsky, N. G. Douglas, M. R. Merrifield, K. Kuijken, M. Arnaboldi, O. Gerhard, K. C. Freeman

Faculty Publications

Owing to the fact that the near future should see a rapidly expanding set of probes of the halo masses of individual early-type galaxies, we introduce a convenient parameter for characterizing the halo masses from both observational and theoretical results: ∇ℓϒ, the logarithmic radial gradient of the mass-to-light ratio. Using halo density profiles from Λ-cold dark matter (CDM) simulations, we derive predictions for this gradient for various galaxy luminosities and star formation efficiencies εSF. As a pilot study, we assemble the available ∇ℓϒ data from kinematics in early-type galaxies – representing the first unbiased study of halo masses in a …

Planetary Transits Of The Trans-Atlantic Exoplanet Survey- Candidate Tres-1b, Aaron Price, Ron Bissinger, Gregory P. Laughlin, Bruce L. Gary, Tonny Vanmunster, Arne A. Henden, Donn Ray Starkey, Daniel H. Kaiser, Jon A. Holtzman, Laurence A. Marschall, Thomas Michalik, T. Wellington, Pertti Paakkonen, Zsolt Kereszty, Russ Durkee, Kent Richardson, Robin Leadbeater, Timothy P. Castellano

Physics and Astronomy Faculty Publications

The AAVSO compiled 10,560 CCD observations of the suspected exoplanet transit object TrES-1b covering seven complete transit windows, three windows of partial coverage, and coverage of baseline non-transit periods. Visual inspection of the light curves reveals the presence of slight humps at the egress points of some transits. A boot strap Monte Carlo simulation was applied to the data to confirm that the humps exist to a statistically significant degree. However, it does not rule out systemic effects which will be tested with campaigns in the 2005 observing season.

Thermal And Mechanical Properties Of Bawo4 Crystal, W. W. Ge, H. J. Wang, J. Y. Wang, J. H. Liu, X. G. Xu, X. B. Hu, M. H. Jiang, D. G. Ran, S. Q. Sun, H. R. Xia, Robert I. Boughton

Physics and Astronomy Faculty Publications

A large single crystal of barium tungstate BaWO4 with dimensions of 22- mm diameter 80-mm length was grown by the Czochralski method using an iridium crucible. The melting point, molar enthalpy of fusion, and molar entropy of fusion of the crystal were determined to be 1775.10 K, 96 913.80 J mol−1, and 54.60 J K−1 mol−1, respectively. The average linear thermal-expansion coefficients are a=10.9526 10−6/K, b=10.8069 10−6 /K, and c =35.1063 10−6 /K in the temperature range from 303.15 to 1423.15 K along the three respective crystallographic axes. The density of the crystal follows an almost linear decrease from 6.393 …

Semi-Relativistic Approximation To Gravitational Radiation From Encounters With Non-Spinning Black Holes, Jonathan R. Gair, Daniel J. Kennefick, Shane L. Larson

All Physics Faculty Publications

The capture of compact bodies by black holes in galactic nuclei is an important prospective source for low frequency gravitational wave detectors, such as the planned Laser Interferometer Space Antenna. This paper calculates, using a semirelativistic approximation, the total energy and angular momentum lost to gravitational radiation by compact bodies on very high eccentricity orbits passing close to a supermassive, nonspinning black hole; these quantities determine the characteristics of the orbital evolution necessary to estimate the capture rate. The semirelativistic approximation improves upon treatments which use orbits at Newtonian order and quadrupolar radiation emission, and matches well onto accurate Teukolsky …

A Hard X-Ray Polarimeter Designed For Transient Astrophysical Sources, Mark L. Mcconnell, Peter F. Bloser, Jason S. Legere, John R. Macri, T Narita

Space Science Center

— This paper discusses the latest progress in the development of GRAPE (Gamma-Ray Polarimeter Experiment), a hard X-ray Compton Polarimeter. The purpose of GRAPE is to measure the polarization of hard X-rays in the 50-300 keV energy range. We are particularly interested in X-rays that are emitted from solar flares and gamma-ray bursts (GRBs). Accurately measuring the polarization of the emitted radiation from these sources will lead, to a better understating of both the emission mechanisms and source geometries. The GRAPE design consists of an array of plastic scintillators surrounding a central high-Z crystal scintillator. We can monitor individual Compton …

Atmospheric Neutron Measurements With The Sontrac Science Model, U Bravar, E O. Fluckiger, Kevin Godin, Zachary C. Hansen, John R. Macri, Mark L. Mcconnell, R S. Miller, M R. Moser, James M. Ryan

Space Science Center

–The SOlar Neutron TRACking (SONTRAC) telescope was originally developed to measure the energy spectrum and incident direction of neutrons produced in solar flares, in the energy range 20 - 250 MeV. While developed primarily for solar physics, the SONTRAC detector may be employed in virtually any application requiring both energy measurement and imaging capabilities. The SONTRAC Science Model (SM) is presently being operated at the University of New Hampshire (UNH) as a ground-based instrument to investigate the energy spectrum, zenith and azimuth angle dependence of the cosmic-ray induced sea-level atmospheric neutron flux. SONTRAC measurements are based on the non-relativistic double …

Continued Studies Of Single-Sided Charge-Sharing Czt Strip Detectors, B Donmez, John R. Macri, Mark L. Mcconnell, James M. Ryan, Mark Widholm, L A. Hamel, T Narita

Space Science Center

In this paper, we report progress in the study of thick single-sided charge-sharing cadmium zinc telluride (CZT) strip detector modules designed to perform gammaray spectroscopy and 3-D imaging. We report on continuing laboratory and simulation measurements of prototype detectors with 11×11 unit cells (15×15×7.5mm3 ). We report preliminary measurements of the 3-D spatial resolution. Our studies are aimed at developing compact, efficient, detector modules for 0.05 to 1 MeV gamma measurements while minimizing the number and complexity of the electronic readout channels. This is particularly important in space-based coded aperture and Compton telescope instruments that require large area, large volume …

Development Of The Fast Neutron Imaging Telescope, U Bravar, P J. Bruillard, E O. Fluckiger, John R. Macri, A L. Mackinnon, Mark L. Mcconnell, M R. Moser, James M. Ryan, R S. Woolf

Space Science Center

We report on the development of a next generation neutron telescope, with imaging and energy measurement capabilities, sensitive to neutrons in the 2-20 MeV energy range. The Fast Neutron Imaging Telescope (FNIT) was initially conceived to study solar neutrons as a candidate instrument for the Inner Heliosphere Sentinels (IHS) program under formulation at NASA. This detector is now being adapted to locate Special Nuclear Material (SNM) for homeland security purposes by detecting fission neutrons and reconstructing the image of their source. In either case, the detection principle is based on multiple elastic neutron-proton scatterings in organic scintillator. By reconstructing the …

Ion Cyclotron Waves In The Saturnian Magnetosphere Associated With Cassini's Engine Exhaust, C. T. Russell, J. S. Leisner, K. K. Khurana, M. K. Dougherty, X. Blanco-Cano, Jane L. Fox

Physics Faculty Publications

Five hours after the orbit insertion maneuver that placed Cassini into orbit about Saturn, a long (90 minute) burst of ion cyclotron waves were seen, very different than any waves on the inbound leg of the orbit or on succeeding orbits. The ion cyclotron waves were left-hand elliptically polarized and propagating at a moderately large angle to the local magnetic field. The waves had a noticeable compressional component consistent with their off angle propagation. The frequency band of the signals was moderately broad and consistent with the singly ionized components of the engine exhaust gases: CO₂, N_{2 …}

Diagnostics Of Disks Around Hot Stars, David H. Cohen, M. H. Hanson, R. H.D. Townsend, K. S. Bjorkman, M. Gagné

Physics & Astronomy Faculty Works

We discuss three different observational diagnostics related to disks around hot stars: absorption line determinations of rotational velocities of Be stars; polarization diagnostics of circumstellar disks; and X-ray line diagnostics of one specific magnetized hot star, theta(1) Ori C. Some common themes that emerge from these studies include (a) the benefits of having a specific physical model as a framework for interpreting diagnostic data; (b) the importance of combining several different types of observational diagnostics of the same objects; and (c) that while there is often the need to reinterpret traditional diagnostics in light of new theoretical advances, there are …

Thorium-Based Thin Films As Highly Reflective Mirrors In The Euv, David D. Allred, William R. Evans, Jed E. Johnson, Richard L. Sandberg, R. Steven Turley

Faculty Publications

As applications for extreme ultraviolet (EUV) radiation have been identified, the demand for better optics has also increased. Thorium and thorium oxide thin films (19 to 61 nm thick) were RF-sputtered and characterized using atomic force microscopy (AFM), spectroscopic ellipsometry, low-angle x-ray diffraction (LAXRD), x-ray photoelectron spectroscopy (XPS), and x-ray absorption near edge structure (XANES) in order to assess their capability as EUV reflectors. Their reflectance and absorption at different energies were also measured and analyzed at the Advanced Light Source in Berkeley. The reflectance of oxidized thorium is reported between 2 and 32 nm at 5, 10, and 15 …

Higher Twist Analysis Of The Proton G₁ Structure Function, M. Osipenko, W. Melnitchouk, S. Simula, P. Bosted, V. Burkert, M. E. Christy, K. Griffioen, C. Keppel, S. E. Kuhn

Physics Faculty Publications

We perform a global analysis of all available spin-dependent proton structure function data, covering a large range of Q², 1 ⩽ Q² ⩽ 30 GeV², and calculate the lowest moment of the g₁ structure function as a function of Q². From the Q² dependence of the lowest moment we extract matrix elements of twist-4 operators, and determine the color electric and magnetic polarizabilities of the proton to be X_E= 0.026 ± 0.015(stat) ± ^0.021_0.024 (sys) and X_B= -0.013 ∓ 0.007(stat) ∓ ^0.010 _0.012(sys), respectively.

The Vlt-Uves Survey For Molecular Hydrogen In High-Redshift Damped Lyman Α Systems: Physical Conditions In The Neutral Gas, Raghunathan Srianand, Patrick Petitjean, Cédric Ledoux, Gary J. Ferland, Gargi Shaw

Physics and Astronomy Faculty Publications

We study the physical conditions in damped Lyman α systems (DLAs), using a sample of 33 systems towards 26 quasi-stellar objects (QSOs) acquired for a recently completed survey of H₂ by Ledoux, Petitjean & Srianand. We use the column densities of H₂ in different rotational levels, together with those of C I, C I*, C I**, C II* and singly ionized atomic species to discuss the kinetic temperature, the density of hydrogen and the electronic density in the gas together with the ambient ultraviolet (UV) radiation field. Detailed comparisons are made between the observed properties in DLAs, the …

Today's Take On Einstein’S Relativity: Proceedings Of The Conference Of 18 Feb 2005, Florentin Smarandache, Homer B. Tilton

Branch Mathematics and Statistics Faculty and Staff Publications

Non Sequiturs in Relativity Four in number at this point Dr. Smith of "Lost in Space" had a knack of easing out of binds that he'd gotten himself into. Dr. Einstein was a little like that. Einstein originally declared that the distortions of special relativity reflect real changes to the objects being remotely observed, then reconsidered. The first non sequitur is quoted here from Sachs:[1] In a lecture that Einstein gave to the Prussian Academy of Sciences in 1921, he said the following: "Geometry predicates nothing about relations of real things, but only geometry together with the purport of physical …

Anisotropic Thermal Expansion Of Monoclinic Potassium Lutetium Tungstate Single Crystals, Kunpeng Wang, Jianxiu Zhang, Jiyang Wang, Huaijin Zhang, Zhengping Wang, Wentao Yu, Xuping Wang, Qingming Lu, Mingfang Ba, Robert I. Boughton

Physics and Astronomy Faculty Publications

The anisotropic thermal expansion of a single crystal of KLu WO4 2 KLuW , obtained by the top-seeded solution growth method, has been investigated over a wide temperature range 50– 600 °C . The linear thermal-expansion tensor has been determined and its principal X, Y, and Z axes are in the 705 , 010 , and 107 crystallographic directions, respectively. The principal thermal-expansion coefficients I, II, and III are 12.8 10−6, 7.8 10−6, and 22.2 10−6 K−1, respectively. The principal axis with maximum thermal expansion Z with III=22.2 10−6 is located at 10.37° from the c axis. In comparison with …