Astrophysics and Astronomy Commons^™

H Ii Region Abundances: Model Oxygen Line Ratios, Stacy S. Mcgaugh

Faculty Scholarship

We present an extensive, homogeneous grid of H II region models. We find that the behavior of the strong oxygen lines can be modeled by taking proper account of the softening of the ionizing spectra pro duced by stars of increasing metallicity. This provides a calibration of the abundance indicating line ratio ([O II] λ3727 + [O III] λλ4959, 5007)/Hβ which is comparable in accuracy to that obtainable by direct methods when a temperature-sensitive line ratio is available. No metallicity dependence of the IMF is required to explain the systematic softening of stellar spectra with increasing metallicity. It results naturally …

Ua11/1 On Campus, Vol. 1, No. 13, Wku University Relations

WKU Administration Documents

On Campus newsletter featuring articles about faculty, staff and events at Western Kentucky University. Regular features are:

• College News
• Sponsored Programs
• Hot off the Press
• Personnel File

This issue includes articles:

• Fifth Women's Studies Conference Opens
• Hardin Planetarium Show Features Sun's Children
• President Thomas Meredith Appointed to Constitutional Improvement Policy Council
• WKU to Begin Reaccreditation Process
• Students Raise $48,715 First Week of Alumni Fund Student Phonathon
• Phillips, Hugh. Russia's Coup; A Historical Perspective
• Esion, Sheila. Jim Wayne Miller's Writing Takes New Shape
• Threads of Compassion: Fabric Art Exhibit by Penny Sisto Opens Tomorrow
• Shuttle May Have Foiled, but Summer Eclipse …

Asteroseismology Of The Dov Star Pg 1159-035 With The Whole Earth Telescope, Donald E. Winget, R. Edward Nather, J. Christopher Clemens, Judith Provencal, Scot J. Kleinman, Paul A. Bradley, Matt A. Wood, Charles F. Claver, Marian L. Frueh, Albert D. Grauer, Butler P. Hine, Carl J. Hansen, Gilles Fontaine, Nicholas Achilleos, Dayal T. Wickramasinghe, T.M.K. Marar, S. Seetha, B. N. Ashoka, Darragh O'Donoghue, Brian Warner, Donald W. Kurtz, David A. Buckley, J. Brickhill, Gerard Vauclair, Noël Dolez, Michel Chevreton, Martin A. Barstow, Jan-Erik Solheim, Antonio Kanaan, Kepler De Souza Oliveira Filho, Gregory W. Henry, Steven D. Kawaler

Information Systems and Engineering Management Research Publications

We report the results from 264.1 hr of nearly continuous time-series photometry on the pulsating pre-white dwarf star (DOV) PG 1159-035. The high-resolution power spectrum of this data set is dominated by power in the range from roughly 1000 to 2600 μHz (1000 s to 385 s periods). This power is completely resolved into 125 individual frequencies; we have identified 101 of them with specific, quantized pulsation modes, and the rest are completely consistent with such modal assignment. The luminosity variations are therefore certainly the result of g-mode pulsations. Although the amplitudes of some of the peaks exhibit significant variations …

Discovery Of A Lyα Galaxy Near A Damped Lyα Absorber At Z = 2.3, James D. Lowenthal, Craig J. Hogan, Richard F. Green, Adeline Caulet, Bruce E. Woodgate, Larry Brown, Craig B. Foltz

Astronomy: Faculty Publications

We report the detection of a galaxy associated with the damped Lyα absorbing cloud seen at z = 2.309 toward the QSO PHL 957 (zem = 2.681). The galaxy was discovered in deep Fabry-Perot narrow-band CCD frames and was subsequently imaged spectroscopically. In addition to a strong but narrow Lyα emission line (FLyα = 5.6 × 10-16 ergs s-1 cm-2, FWHM ∼ 700 km s-1) and weaker C IV and He II lines, the object shows continuum at V ∼ 24, with a slope (in Fν) rising slightly toward the red, similar to what is seen in high-redshift radio galaxies; …

Simultaneous Light And Radial Velocity Curve Solutions For U Cephei, James Bruce Rafert, N L. Markworth

Aerospace, Physics, and Space Science Faculty Publications

The light-curve synthesis approach of Wilson & Devinney has been used to solve simultaneously light and radial velocity curves of the Algol-type eclipsing binary star U Cephei. We have performed eight new differential corrections solutions using the photometric data of Markworth and the radial velocity data of Batten to obtain a consistent set of orbital and astrophysical parameters for the light and velocity curves of this famous system. We find U Cephei to be best modeled using the semidetached (mode 5) system geometry of the Wilson & Devinney program, with a primary rotating at about 5.2 times its synchronous rate, …

Photometry Of The Chromospherically Active Binary Hd 197010, Laurence A. Marschall, Harold L. Nations, B. W. Taylor, T. L. Huard

Physics and Astronomy Faculty Publications

For the past several years we have been conducting a study of the spectroscopic and photometric characteristics of a sample X-ray emitting stars from the Einstein Observatory Medium Sensitivity Survey identified as probable binary systems by Fleming (1988) and Fleming, et al.(1989). One of these stars, HD 197010 ( = 1E2038.3-0046 = SAO 144692 = BD -1degree 4025) was discovered to be a short period eclipsing binary by Robb, et al.(1990). The ephemeris he presented was based on observations in 1989 and 1990, but only the 1990 observations included points at eclipse minimum. We report here on first results of …

Emission From The Z = 2 Damped Lyα Absorber Toward Q1215 + 333, Richard Elston, Jill Bechtold, James Lowenthal, Marcia Rieke

Astronomy: Faculty Publications

We have detected narrow emission lines at 1.118 μm and 1.456 μm in the spectrum of the z = 2.606 quasar Q1215 + 333, corresponding to [O II] λ3727 and Hβ at z = 1.9984, the redshift of a damped Lyα absorber toward this quasar. The intensity of the Hβ line is 7.6 ± 2 × 10-16 ergs cm-2 s-1, which corresponds to a line luminosity of 5 × 1042 ergs s-1 h-2100 (q0 = 0.5). If we assume that the photoionization producing the emission is due purely to massive star formation with a Salpeter initial mass function, we find …

The Extraordinary 1989 December 14/15 Optical Flare Events On V711 Tauri, Gregory W. Henry, Douglas S. Hall

Information Systems and Engineering Management Research Publications

Photometry in B and V taken with the Vanderbilt Tennessee State 16 inch (41 cm) robotic telescope confirms the intense broad-band optical continuum flare activity reported by Chinese observers on the active chromosphere binary V711 Tau on December 14/15, 1989. Twelve hours after the flare reported from China, there occurred a separate and more intense flare with B and V amplitudes of 0.69 and 0.42 mag, respectively. These amplitudes correspond to peak flare luminosities of approximately 2 x 10 to the 33rd ergs/s in B and 1 x 10 to the 33rd ergs/s in V. The observed color of its …

Chromospherically Active Stars. Viii. Hd 155683 = V972 Herculis: Observational Constraints On Evolutionary Theory, Francis C. Fekel

Information Systems and Engineering Management Research Publications

V792 Her is an eclipsing RS CVn binary with an orbital period of 27.54 days whose components have spectral types of K0 III and F2 IV. New spectroscopic observations combined with existing photometry have resulted in masses of 1.47 + or - 0.003 solar mass and 1.41 + or - 0.003 solar mass for the K giant and F star, respectively. Additional fundamental parameters are derived. Standard evolutionary models were specifically computed by VandenBerg (1990) for the two stars. The best fit occurs if the components are somewhat metal poor with Fe/H/ = - 0.46. Ages of about 2.3 x …

The Physical Properties Of Double Degenerate Common Proper Motion Binaries, Edward M. Sion, Terry D. Oswalt, James Liebert, Paul Hintsen

Aerospace, Physics, and Space Science Faculty Publications

We present spectral types and spectrophotometry for 21 double degenerate (DD) common proper motion binaries and provide estimates of their colors, absolute visual and bolometric magnitudes, and cooling ages. The most typical double degenerate pair contains stars of similar color and spectral type, with an average Mv = 14.20, and average cooling age of ≈3×10⁹ yr, thus typically belonging to the extremely old disk population subcomponent. The oldest pairs in the sample are 9 × 10⁹ yr. The differential cooling ages, Δ log τc, range between 0.01 and 0.84, with the most typical pair having Δ log τc = 0.30, …

Fluctuations In Astronomical Masers, Moshe Elitzur

Physics and Astronomy Faculty Publications

The radiation of astronomical masers fluctuates on the time scale 1/Gamma, where Gamma is the levels' loss rate. These intensity fluctuations reflect fluctuations of the level poulations around their mean, steady state values over the length scale λ_c = c/Γ. In saturated masers, the intensity fluctuations are dominated by passage through the unsaturated core. The effects of the saturated zones and of the seed radiation that the masers amplify can be neglected.

These fluctuations may have been detected in recent observations by Clegg and Cordes (1991) of Galactic H II/OH masers, providing a possible direct determination of the …

Polarization Of Astronomical Maser Radiation, Moshe Elitzur

Physics and Astronomy Faculty Publications

The polarization of maser radiation when the source is permeated by an aligned magnetic field is derived for arbitrary angular momenta of the transition states. This generalization is made possible by an analysis of the structure of the propagating waves in a frame aligned with the magnetic axis. The key elements in determining the polarization properties are the assumption of independent and incoherent pump and loss processes for all magnetic sublevels, and the beaming of maser radiation. The radiation propagating in the direction of maximal intensity growth is polarized according to the solutions derived by Goldreich, Keeley, and Kwan for …

Theory Of An Atomic Beam Splitter Based On Velocity-Tuned Resonances, Scott Glasgow, P. Meystre, M. Wilkens, E. M. Wright

Faculty Publications

We develop the theory of an atomic beam splitter in which a monoenergetic beam of two-level atoms is incident normally to a classical standing-wave light field. The incident atomic wave function can be split into two coherent components with transverse momenta ±(2n + 1)fzk using velocity-tuned resonances, where n is the order of the resonance. We discuss the cases of zero- and first-order resonances in detail, and show that the velocity-tuned resonances are renormalized due to a high-frequency Stark shift. Numerical results that display the effects of a finite momentum spread in the incident atomic beam are presented.

Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a: Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, James W. Liebert, Gary Wegner, Detlev Koester, Pamela M. Marcum

Aerospace, Physics, and Space Science Faculty Publications

We present a high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W₂₄₇₉ = 2.35 ± 0.06 Å from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 ± 0.2). The presence of carbon in a Herich atmosphere lends credence to the notion that LDS 678A is a transitional case between the DB …

Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner

Dartmouth Scholarship

A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 + or - 0.06 A from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 + or- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case …

Radiative Transfer In Astronomical Masers. Iii. Filamentary Masers, Moshe Elitzur, Christopher F. Mckee, David J. Hollenbach

Physics and Astronomy Faculty Publications

This paper, the last in a series, presents the complete solution of a filamentary maser. The contribution of rays emanating from the filament sidewall is essential for the solution self-consistency during saturation. We develop an integral equation to calculate this contribution, devise an iteration scheme to solve it, and perform the first two iterations. The solution provides complete expressions for the distributions of intensity and flux across the source as functions of position and direction with regard to the axis. One consequence of radiation beaming, somewhat surprising at first, is that the filament appears smaller when viewed off-axis, at angles …

A Search For Embedded Young Stellar Objects In And Near The Ic 1396 Complex, Richard Schwartz, Bruce Wilking, Armen Giulbudagian

Physics Faculty Works

The IRAS data base is used to locate young stellar object candidates in and near the IC 1396 complex located in the Cepheus OB2 association. Co-added survey data are used to identify all sources with a flux density Snu(100) greater than 10 Jy and with Snu(100) greater than Snu(60). The 15 sources located at the positions of globules and dark clouds are further analyzed using the in-scan slices to assess the source profiles

A Space-Based Solar Screen Against Climatic Warming, Michael Noah Mautner

Chemistry Publications

The expected global warming may be reversed by space-based screen that would intercept a fraction of the solar radiation incident on Earth. Warming by 2-5^oC could be prevented by intercepting 3-7%, respectively, of the incident solar radiation. The screen may be constructed for example of a thin film, a grid of film supported by a mesh or fine-grained dust deployed in orbit about the Earth. For an average film thickness or particle radius of 0.001 cm, the required mass is 10¹⁴ - 10¹⁵ g, equivalent to a medium sized lunar mountain or asteroid. The material may …

Simultaneous Light And Radial Velocity Curve Solutions For U Cephei, J. B. Rafert, N. L. Markworth

Faculty Publications

The light-curve synthesis approach of Wilson & Devinney has been used to solve simultaneously light and radial velocity curves of the Algol-type eclipsing binary star U Cephei. We have performed eight new differential corrections solutions using the photometric data of Markworth and the radial velocity data of Batten to obtain a consistent set of orbital and astrophysical parameters for the light and velocity curves of this famous system. We find U Cephei to be best modeled using the semidetached (mode 5) system geometry of the Wilson & Devinney program, with a primary rotating at about 5.2 times its synchronous rate, …

Nonequilibrium Processes In Polymers Undergoing Interchange Reactions. Part 2: Reaction-Diffusion Processes, Alejandro Garcia, J. Pojman, D. Kondepudi, C. Van De Broeck

Faculty Publications

A reactiodffusion system of polymers undergoing interchange reactions is studied. The equation that describes the dynamics of the system is similar to the Boltzmann equation for a gas of hard spheres. We consider a one-dimensionsl system in which the average length and the concentrations at the boundaries are fixed. The resulting steady states are obtained analytically and with numerical integration of equations obtained by using a local equilibrium approximation. Monte Carlo simulations of experimentally realizable conditions were performed and compared. The results reveal a nonlinear distribution of molecular concentration and mass. The entropy of the polymer distributions is calculated as …

Determination Of Rate Distributions From Kinetic Experiments, Todd B. Sauke, P. J. Steinback, K. Chu, H. Frauenfelder, J. B. Johnson, D. C. Lamb, G. U. Nienhaus, R. D. Young

Faculty Publications

Rate processes in proteins are often not adequately described by simple exponential kinetics. Instead of modeling the kinetics in the time domain, it can be advantageous to perform a numerical inversion leading to a rate distribution function f(lambda). The features observed in f(lambda) (number, positions, and shapes of peaks) can then be interpreted. We discuss different numerical techniques for obtaining rate distribution functions, with special emphasis on the maximum entropy method. Examples are given for the application of these techniques to flash photolysis data of heme proteins.

Comptel Images Locations Of Gamma‐Ray Bursts, M Varendorff, K Bennett, H Deboer, M Busetta, H Bloemen, W Collmar, A Connors, R Diehl, J W. Den Herder, W Hermsen, R M. Kippen, L Kuiper, G G. Lichti, J Lockwood, Mark L. Mcconnell, D Morris, R Much, James M. Ryan, V Schonfelder, G Stacy, H Steinle, A W. Strong, B Swanenburg, C De Vries, C Winkler

Space Science Center

The γ‐ray telescope COMPTEL onboard GRO has so far located 6 gamma‐ray bursts which occurred in its ∼1 sr field of view. The positions of the sources were derived by the maximum‐entropy method. Systematic and statistical uncertainties for the four strongest bursts are approximately 1° to 2° and can be reduced in future analysis.

Comptel Observations Of Cosmic Gamma‐Ray Bursts, C Winkler, K Bennett, H Bloemen, H Deboer, W Collmar, A Connors, R Diehl, L O. Hanlon, J W. Den Herder, W Hermsen, L Kuiper, R M. Kippen, G G. Lichti, J Lockwood, Mark L. Mcconnell, D Morris, James M. Ryan, V Schonfelder, G Stacy, H Steinle, A W. Strong, B Swanenburg, B G. Taylor, M Varendorff, C De Vries, O R. Williams, M Busetta

Space Science Center

The imaging γ‐ray telescope COMPTEL on board NASA’s Compton Gamma‐Ray Observatory (GRO) has observed many cosmic gamma‐ray bursts during the early mission phase of GRO. COMPTEL records time‐resolved burst spectra over 0.1 MeV to 10 MeV energies, and, for the first time, produces direct single‐telescope gamma‐ray images (0.8–30 MeV) of cosmic gamma‐ray bursts occurring in its 1 sr field of field.

Shadow Casting Phenomena At Newgrange, Frank Prendergast

Articles

A digital model of the Newgrange passage tomb and surrounding ring of monoliths known as the Great Circle is used to investigate sunrise shadow casting phenomena at the monument. Diurnal variation in shadow directions and lengths are analysed for their potential use in the Bronze Age to indicate the passage of seasonal time. Computer-aided simulations are developed from a photogrammetric survey to accurately show how three of the largest monoliths, located closest to the tomb entrance and archaeologically coded GC1, GC-1 and GC-2, cast their shadows onto the vertical face of the entrance kerbstone, coded K1. The phenomena occur at …

Diffuse Band Profiles In The Spectrum Of Hd 29647: Evidence For A Molecular Origin?, Theodore P. Snow, C G. Seab

Physics Faculty Publications

High signal-to-noise ratio spectra have been obtained of the diffuse interstellar bands at 5780 and 5797 Å in the spectrum of HD 29647, a heavily reddened star within or behind a portion of the Taurus dark cloud complex. The observations were made using the coudé spectrograph on the Canada-France-Hawaii Telescope. The Reticon detector combined with the coudé spectrograph and excellent observing conditions allowed S/N ratios as high as 200 for this star, which was V=8.37 and E(B–V)=1.03. In two separate exposures both bands were found to be narrower and weaker than normal values for …

The Transmittances Of Thin Polymer Films And Their Suitability As A Supportive Substrate For A Soft X-Ray Solar Filter, Memorie Williams, Evan Hansen, A. Reyes-Mena, David D. Allred

Faculty Publications

This paper discusses soft x-ray filter designs for the Brigham Young University "Goldhelox Project". Three polymers intended for use as a supportive substrate for a soft x-ray solar filter, having a passband centered at 171 angstroms are examined. The use of polymer substrates is examined because of vibrational and mechanical stresses associated with the shuttle launch, preventing the use of a free standing filter, and because of Goldhelox's special need to locate the filter near the imaging plane. The uniform consistency of a polymer support will prevent any imaging of the filter support structure, as would occur if a traditional …

Structure And Optical Characterization Of Znxcd1-Xte Thin Films Prepared By The Close Spaced Vapor Transport Method, David D. Allred, Jesus González-Hernández, O. Zelaya, J. G. Mendoza-Alverez, E. López-Cruz, D. A. Pawlik

Faculty Publications

Zinc cadmium telluride (ZnxCd1-xTe) solid solution films with 0≤x≤0.12 were deposited by the close spaced vapor transport method and characterized using photoluminescence, x-ray diffraction, and scanning electron microscopy. The two former techniques indicate that films with high crystalline quality can be prepared with moderate substrate temperatures and low argon pressures. Under these conditions deposition rates of up to 1000 Å/s are achieved and Zn concentration in the film is the same as that of the source. The electron micrographs show grain sizes comparable to the film thickness.

Forbidden Lines Of Np^Q Ions. Ii. Line Intensities, J. P. Lynch, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

Ground state forbidden transitions of np^q ions of C, N, 0, Ne, Mg, Si, S, and Fe can provide important information on the state of cosmic ionized gases. Wavelengths of these lines are in the far- and near-UV visible and near- and far-IR regions of the spectrum. The line intensity ratios of particular transitions in q = 2, 4 ions can provide information on the temperature of the gas and in q = 3 ions information on the density of the gas. In the present work we have tabulated the line intensities of 95 transitions of these ions, which include …

Ultraviolet And Optical Spectroscopy Of The R Aquarii Symmetrical Jet, J. M. Hollis, R. J. Oliverson, Menas Kafatos, A. G. Michalitsianos, R. M. Wagner

Mathematics, Physics, and Computer Science Faculty Articles and Research

The first ultraviolet spectrum of the southwest (SW) component of the symmetrical jet in the R Aquarii binary system has been obtained in the range 1200-2000 A with the International Ultraviolet Explorer (IUE). These results are compared to more encompassing spectra (1200-3200 A) of the central H II region taken at the same time and also similar spectra of the northeast (NE) jet component obtained 6 months earlier. Moreover, optical spectra of both the NE and SW jet components in the range 3400-9800 A were obtained within ~ 6 months and ~ 1 month, respectively, of the ultraviolet spectra. These …

Realistic Orbits About The Martian Moons, Samuel R. Bryant

Theses and Dissertations

Orbits about the Martian moons, Phobos and Deimos, previously found to be stable by the Poincare surface of section technique in a restricted three- body system, were investigated with non-zero eccentricity of the moons added to the dynamics of the planar four-body system (Mars, moon sun, artificial satellite). Although not strictly applicable to this case, the surface of section technique was used to verify whether or not the previously found stable orbits were realistic when a real world perturbation was added to the system dynamics. The surface of section technique involves the numerical integration of several orbits with the same …