Physical Sciences and Mathematics Commons^™

Co Emission In The Radio-Loud Quasar 3c 48, N Z. Scivukke, S Padin, D B. Sanders, B T. Soifer, Min S. Yun

Min S. Yun

We have used the Owens Valley Millimeter Array to conduct a sensitive search for CO (1 - 0) emission in the radio-loud quasar 3C 48. An emission feature is detected (4σ) at the redshift of the narrow optical emission lines (z = 0.3695). The width of this feature is ~250 km s^-1^(FWHM) similar to that expected for a galactic disk, and the integrated CO line flux implies an H_2_ mass of 7 x 10^10^ M_sun_ (assuming the same CO to H_2_ conversion factor found for giant molecular clouds in the Milky Way). This H_2_ mass is ~30 times that for …

Spot On Rs Cvn From Spectroscopy And Photometry, Joel A. Eaton, Gregory W. Henry, Coretta Bell, Albert Okorogu

Information Systems and Engineering Management Research Publications

We have used contemporaneous spectra and V light curves to form spot models for RS CVn in 1991 and 1992. More than two spots are needed to fit all the properties of the observations. In fact, moderately small spots (22 x 28 deg in latitude and longitude) having only a slight effect on the rotational light curve were eclipsed in both years, and we find that a collection of 6-8 such moderate spots is required to fit the line profiles in each year. These groups of spots also account naturally for a difference in level of light between the two …

The Spectroscopic Orbit Of Gamma Geminorum And A Search For Its Secondary, Francis C. Fekel, Jocelyn Tomkin

Information Systems and Engineering Management Research Publications

New spectroscopic observations of Gamma Geminorum, a bright, 'normal' A1 IV star have resulted in an improved spectroscopic orbit. The orbital period is 12.632 +/- 0.002 yr, the eccentricity is 0.893 +/-0.002, and the orbital parallax is 0.0291 +/-0.0024 arcsec, or a distance of 34 pc. We determine a v sin i of 8 +/-1 km/s for the A star, which confirms that it is a slow rotator. Near-infrared spectroscopic observations at 8806 A, obtained through the brief nodal passage, have resulted in the probable detection of the secondary. The masses are 2.8 and 1.07 solar mass and the Delta …

Radial-Velocity And Light Variations Of Ir Cephei, Laurence A. Marschall, Michael A. Seeds, Robert J. Davis

Physics and Astronomy Faculty Publications

Radical-velocity observations of the short-period Cepheid, IR Cephei, have been used to derive a complete radial-velocity versus phase curve for the variable, to investigate the presence of a possible binary companion, and to address the question of its membership in the Cepheus OB2 association. The observations are consistent with the absence of a close binary companion and shed doubt on its membership in the association. Photoelectric observations made with the Phoenix 10 Automated Photometric Telescope confirm the single nature of the star. We present simulations to show the effects of an equiluminous companion on the light curve of a Cepheid, …

A Masing [Fe Xi] Line, Gary J. Ferland

Physics and Astronomy Faculty Publications

I draw attention to a maser which occurs within the ground term of Fe¹⁰⁺. In many photoionized environments, infrared fine-structure lines and the [O I] λ6300 line become optically thick but maser amplification of ionic fine-structure lines is unusual. During the course of development of a code designed to simulate gas under radiative-collisional equilibrium, the radiative transfer of roughly 500 ionic/atomic emission lines was treated using escape probabilities. Nearly all forbidden lines can become optically thick under extreme conditions, but the ³Pj = 1, 0 [Fe XI] 6.08 μm transition is the only line …

On The Escape Of Oxygen And Hydrogen From Mars, Jane L. Fox

Physics Faculty Publications

Escape rates of oxygen atoms from dissociative recombination of O₂⁺ above the Martian exobase are computed in light of new information from ab initio calculations of the dissociative recombination process, and our recently revised understanding of the Martian dayside ionosphere. Only about 60% of the dissociative recombinations occur in channels in which the O atoms are released with energies in excess of the escape velocity. Futhermore, we find that the computed escape fluxes for O depend greatly on the nature of the ion loss process that has been found necessary to reproduce the topside ion density profiles measured …

Upper Limits To The Nightside Ionosphere Of Mars, Jane L. Fox

Physics Faculty Publications

The nightside ionosphere of Mars could be produced by electron precipitation or by plasma transport from the dayside, by analogy to the Venus, but few measurements are available. We report here model calculations of upper limits to the nightside ion densities on Mars that would be produced by both mechanisms. For the auroral model, we have adopted the downward traveling portions of the electron spectra measured by the HARP instrument on the Soviet Phobos spacecraft in the Martian plasma sheet and in the magnetotail lobes. For the plasma transport case, we have imposed on a model of the nightside thermosphere, …

H I Streamers Around M82 - Tidally Disrupted Outer Gas Disk, Min S. Yun, Paul T P Ho, K Y. Lo

Min S. Yun

Our new VLA observations of M82 reveals a triangular central concentration of neutral atomic gas and several more than about 10 kpc long tidal streamers originating from M82 itself. The coincidence of the beginning of the tidal streamer with the flaring of the optical disk as well as the smooth continuation of the disk velocity field into the H I streamer strongly suggest the tidal disruption of the disk of M82, contrary to the widely proposed scenario of tidal stripping and gas accretion from its neighbor M81. The velocity characteristics of H I within M82 are that of disk rotation …

Ccd Photometry Of The Old Open Cluster M67, Kent A. Montgomery, Laurence A. Marschall, Kenneth A. Janes

Physics and Astronomy Faculty Publications

We present a CCD photometric survey of the central one-half degree of the old open cluster, M67, in U, B, V, and I colors to magnitude V=20. Extensive comparison of our photometry with other published datasets shows excellent agreement, indicating that CCD photometry is capable of producing a uniform set of measurements consistent with the photometric system defined primarily by the Landolt standard sequence. The color-magnitude diagram of the cluster shows a well-defined main sequence extending at least to the limit of the photometry at Mv=10.55 and a substantial binary sequence. At least 38% of cluster stars are …

The Narrow-Line Region Of High-Luminosity Active Galactic Nuclei, Beverley J. Wills, H. Netzer, M. S. Brotherton, Mingsheng Han, D. Wills, J. A. Baldwin, Gary J. Ferland, I. W. A. Browne

Physics and Astronomy Faculty Publications

We have made high signal-to-noise spectroscopic observations of seven radio-loud quasars with the Faint Object Spectrograph on the Hubble Space Telescope and from the ground at McDonald Observatory and at Kitt Peak National Observatory. The resolution is 300-400 km s^-1 over the wavelength range 1000-8500 Å, enabling us to separate the broad and narrow components of the emission lines. This is the first study of the optical and UV narrow lines in such high-luminosity active galactic nuclei (AGNs).

The most important and striking observational result is the relative weakness of the narrow ultraviolet lines, assuming that they have …

The Dynamics Of Stellar Outflows Dominated By Interaction Of Dust And Radiation, Nathan Netzer, Moshe Elitzur

Physics and Astronomy Faculty Publications

Wind outflow around a late-type star driven by radiation pressure on dust grains is investigated in detail. The equation of motion for the outflow coupled with the equation of radiative transfer is solved treating the circumstellar envelope, which consists of gas and dust, as a two-component fluid. Because of the drift of the dust particles through the gas, the dust-to-gas ratio varies with distance even if grain formation is a prompt process. The coupling between dust and gas weakens as the mass-loss rate decreases until finally the rate of momentum transfer to the gas is insufficient to overcome gravity when …

Photometric And Spectroscopic Observations Of Sn 1990e In Ngc 1035: Observational Constraints For Models Of Type Ii Supernovae, Brian P. Schmidt, Robert P. Kirshner, Rudolph Schild, Bruno Leibundgut, David Jeffery, S. P. Willner, Reynier Peletier, Ann I. Zabludoff, Mark M. Phillips, Nicholas B. Suntzeff, Mario Hamuy, Lisa A. Wells, Chris Smith, Jack A. Baldwin, W. G. Weller, M. Navarette, L. Gonzalez, Alexei V. Filippenko, Joseph C. Shields, Charles C. Steidel, Saul Perlmutter, Carlton R. Pennypacker, Craig K. Smith, Alain C. Porter, Todd A. Boroson, Raylee Stathakis, Russell Cannon, J. Peters, E. Horine, Kenneth C. Freeman, Donna S. Womble, Remington P.S. Stone, Laurence A. Marschall, Andrew C. Phillips, A. Saha, Howard E. Bond

Physics and Astronomy Faculty Publications

We present 126 photometric and 30 spectral observation of SN 1990E spanning from 12 days before B maximum to 600 days past discovery. These observations show that SN 1990E was of type II-P, displaying hydrogen in its spectrum, and the characteristic plateau in its light curve. SN 1990E is one of the few SNe II which has been well observed before maximum light, and we present evidence that this SN was discovered very soon after its explosion. In the earliest spectra we identify, for the first time, several N II lines. We present a new technique for measuring extinction to …

Chromospherically Active Stars. X. Spectroscopy And Photometry Of Hd 212280, Francis C. Fekel, Jared C. Browning, Gregory W. Henry, Mary D. Morton, Douglas S. Hall

Information Systems and Engineering Management Research Publications

The system HD 212280 is a chromospherically active double lined spectroscopic binary with an orbital period of 45.284 days and an eccentricity of 0.50. The spectrum is composite with spectral types of G8 IV and F5-8 V for the components. An estimated inclination of 78 +/- 8 deg results in masses of 1.7 and 1.4 solar mass for the G subgiant and mid-F star, respectively. The distance to the system is estimated to be 112 pc. Photometric observations obtained between 1987 November and 1992 June reveal that HD 212280 is a newly identified variable star with a V amplitude of …

Instrument Description And Performance Of The Imaging Gamma-Ray Telescope Comptel Aboard The Compton Gamma-Ray Observatory, V. Schonfelder, H. Aarts, K Bennett, H Deboer, J. Clear, W Collmar, A Connors, A. Deerenberg, R Diehl, A. Von Dordrecht, J W. Den Herder, W Hermsen, R M. Kippen, L Kuiper, G G. Lichti, J Lockwood, John R. Macri, Mark L. Mcconnell, D Morris, R Much, James M. Ryan, G. Simpson, M. Snelling, G Stacy, H Steinle, A W. Strong, B Swanenburg, B G. Taylor, C De Vries, C Winkler

Space Science Center

The COMPTEL instrument aboard the COMPTEL Gamma-Ray Observatory and its performance capabilities are described. Calibration data are used to determine the angular and energy response, and the effective detection area. The imaging properties of COMPTEL are demonstrated, and the sensitivity of Comptel to celestial gamma-ray sources are estimated from flight data.

Digital Imaging In The Introductory Astronomy Course, Laurence A. Marschall, Michael B. Hayden

Physics and Astronomy Faculty Publications

The availability of small, inexpensive CCD cameras is making it possible to offer non-science students in introductory astronomy courses hands-on experience in astronomical imaging. For the past three years at Gettysburg College we have been developing laboratory exercises using ST-4, ST-6, and Lynxx CCD cameras attached to 8-inch telescopes. We discuss the hardware and the procedures involved in these exercises, pointing out the benefits and limitations of digital observations with introductory students. We also offer tips for making successful observations with students, and describe plans for further development.

Large Amplitude L=1 Coherent Structures In Non-Neutral Plasmas Confined In A Cylindrical Trap, Ross L. Spencer, Grant W. Mason

Faculty Publications

The computation of l= 1 coherent structures in non-neutral plasmas with arbitrary density profiles and for large displacements of the plasma from the symmetry axis of a confining cylindrical trap is described. As the structures are displaced from the axis, they revolve about the symmetry axis with a frequency that typically increases with displacement. The plasma also is distorted into an approximately elliptical shape. The frequency shifts and the eccentricities as a function of displacement, plasma size, and the shape of the density profile are both computed numerically and calculated analytically. The results are shown to be consistent with data …

Photoluminescence And Absorption Studies Of Defects In Cdte And Znxcd1-Xte Crystals, Cheryl Barnett Davis, David D. Allred, A. Reyes-Mena, Jesus González-Hernández, Ovidio González, Bret C. Hess, Worth P. Allred

Faculty Publications

We have studied at cryogenic temperatures photoluminescence features which lie more than 0.15 eV below the band edge in ZnxCd1-xTe (0≤x≤0.09) crystals. The same features, namely a defect band which lies at about 0.13-0.20 eV below the band-gap energy and a peak at 1.1 eV, that are observed in pure CdTe samples are observed in these alloy materials. In annealed samples we observe that the 1.1 eV feature, which has been attributed to tellurium vacancies, increases with fast cooling. Increased concentrations of tellurium vacancies can be understood in terms of the phase diagram of CdTe which indicates that higher concentrations …

Photoelectric And Ccd Photometry Of E And S0 Galaxies, M. Colless, D. Burstein, G. Wegner, R. P. Saglia

Dartmouth Scholarship

We present BR photoelectric photometry for 352 E and S0 galaxies that are part of a large survey of the properties and peculiar motions of galaxies in distant clusters. Repeat measurements show our internal errors to be 2 – 3 per cent in B and R and 1 – 2 per cent in B– R. Comparisons of BR and BVR reductions for 10 galaxies also observed in V show small systematic errors due to differences between the spectral energy distributions of stars and galaxies. External comparisons with B– V colours in the literature confirm that these colours are …

Observations Of The Ca Ii Infrared Triplet In Chromospherically Active Single And Binary Stars, Robert C. Dempsey, Bernard W. Bopp, Gregory W. Henry, Douglas S. Hall

Information Systems and Engineering Management Research Publications

Spectroscopic observations of the Ca II infrared triplet (8498, 8542, 8662 A) have been obtained for 45 stars which are known or suspected to be chromospherically active. The sample includes both single and binary stars of spectral types from F2 to M5 spanning luminosity classes III, IV, and V. Several different types of activity diagnostics were measured, and their relative merits are discussed. Dependence of chromospheric emission upon rotation period, luminosity, temperature, and duplicity are analyzed. Synchronous binaries show a slight trend of increased emission with decreasing period while the asynchronous binaries show abnormally high activity levels for their rotation …

Distinguishing A Charged Higgs Signal From A Heavy Wr Signal, David I. Kaiser

Dartmouth Scholarship

It is shown that non-Standard Model bosons should obey an observable asymmetry in their decays to taus. This asymmetry enables a distinction to be made between charged Higgsboson signalsand heavy right-handed Wboson signals,by reconstructing the orientation of the z with respect to the beam axis.

Microjansky Source Counts And Spectral Indices At 8.44 Ghz, Rogier A. Windhorst, Edward B. Fomalont, R. Bruce Partridge, James D. Lowenthal

Astronomy: Faculty Publications

We used the VLA to make deep images of two 7′ × 7′ fields at 8.44 GHz with 10″ resolution. With an rms noise of 3.2 and 5.1 μJy, respectively, in the two fields, we compiled a catalog of 82 sources. From the complete sample of 20 sources with S ≥ 14.5 μJy, the differential 8.44 GHz source count is dN(S)/ dS = (-4.6 ± 0.7) × S-2.3 ± 0.2 Jy-1 sr-1 in the range 14.5-1000 mJy. Analysis of statistical image fluctuations from weak sources (Fomalont et al. 1993) suggests that this slope remains unchanged at γ = 2.3 ± …

The Triple Symbiotic System Ch Cygni, Kenneth H. Hinkle, Francis C. Fekel, Diana S. Johnson, Werner W.G. Scharlach

Information Systems and Engineering Management Research Publications

Analysis of high-resolution IR spectra of CH Cygni shows that the star is a triple system with a short period orbit of just over 2 yrs. The period ratio of seven for CH Cyg is the smallest known for a triple system. The symbiotic pair is the short-period system. An eccentric and a circular orbit solution are determined for the short-period pair, and the circular orbit solution is found to be more appropriate. The observed eccentricity appears to be due to phase-dependent line asymmetries resulting from the irradiation of the M giant by the white dwarf. The system does not …

The Measurement Of Astronomical Parallaxes With Ccd Imaging Cameras On Small Telescopes, Stephen J. Ratcliff, Thomas J. Balonek, Laurence A. Marschall, David L. Dupuy, Carlton R. Pennypacker, Ritu Verma, Anastasia Alexov, Vivian Bonney

Physics and Astronomy Faculty Publications

Small telescopes equipped with charge-coupled device (CCD) imaging cameras are well suited to introductory laboratory exercises in positional astronomy (astrometry). An elegant example is the determination of the parallax of extraterrestrial objects, such as asteroids. For laboratory exercises suitable for introductory students, the astronomical hardware needs are relatively modest, and under the best circumstances, the analysis requires little more than arithmetic and a microcomputer with image display capabilities. Results from the first such coordinated parallax observations of asteroids ever made are presented. In addition, procedures for several related experiments, involving single-site observations and/or parallaxes of earth-orbiting artificial satellites, are outlined.

Low-Frequency Feature In The First-Order Raman Spectrum Of Amorphous Carbon, David D. Allred, Qi Wang, Jesus González-Hernández

Faculty Publications

In the first-order Raman spectrum of amorphous carbon (a-C) there is a low-frequency feature in the 200-900-cm-1 region. This feature is characteristic of the highly disordered amorphous-carbon materials. We note that the intensity of this feature is very sensitive to the thermal history of samples, thus suggesting that it is an important measure of the degree of disorder of the a-C materials. We also discuss the relationship between this feature and the phonon density of states of graphite.

Exponential Growth Of An Unstable L=1 Diocotron Mode For A Hollow Electron Column In A Warm-Fluid Model, S. Neil Rasband, Ross L. Spencer, Richard R. Vanfleet

Faculty Publications

Numerical investigations of a warm-fluid model with an isothermal equation of state for the perpendicular dynamics of an axisymmetric, magnetically confined pure electron plasma predict an exponentially unstable, l=1, diocotron mode for hollow density profiles. The unstable mode can be identified with a stable, nonsmooth mode that exists in cold drift models but which is destabilized by finite temperature effects. The unstable mode has many properties similar to the experimental results reported by Driscoll [Phys. Rev. Lett. 64, 645 (1990)].

Limits To Cosmic Background Radiation Fluctuations At 8.44 Ghz Between Angular Scales 10″ And 200″, Edward B. Fomalont, R. Bruce Partridge, James D. Lowenthal, Rogier A. Windhorst

Astronomy: Faculty Publications

We have used the VLA at 8.44 GHz to measure fluctuations in the cosmic background radiation (CBR) from two deep images, each 7′ x 7′ in size. No fluctuations between the angular scales 10″ and 200″ were detected. The most accurate limit (95% confidence) is ΔT/TCBR < 1.9 x 10-5 for 80″ resolution. For random Gaussian fluctuations with coherence angle θc, the limits are ΔT/TCBR < 30 x 10-5 for 22″ < θc < 60″. Outside this range the limits increase to ΔT/TCBR < 5 x 10-5 at θc = 12″ or 100″ and ΔT/TCBR < 10 x 10-5 at θc = 5″ or 120″. Similar limits have been obtained for the circularly and linearly polarized components of the CBR fluctuations. These limits were derived from the residual fluctuations in the images after (1) removing brighter foreground sources (> 14.5 μJy) which covered about 10% of each image; (2) estimating fluctuations of weaker sources by extrapolating the count of dN/dS = 4.6S-2.3 Jy-1 sr-1 to 4 μJy; and (3) determining fluctuations from receiver noise and instrumental errors by comparing the image variances from two independent halves of the data set. All analysis was …

Lithium And Rapid Rotation In Chromospherically Active Single Giants, Francis C. Fekel, Suchitra C. Balachandran

Information Systems and Engineering Management Research Publications

The rotational velocities presently obtained via spectroscopic observations of a group of moderately rapidly rotating, chomospherically active single giants indicate that Gray's (1989) rotostat hypothesis requires modification. Their rapid rotation appears to be due to high Li abundances, and results in increased chromospheric activity. A scenario is projected in which the surface convection zone reaches the rapidly rotating core just as a star begins its first ascent of the giant branch, and dredges both high angular momentum material and freshly synthesized Li to the surface.

The Soliton Transform And A Possible Application To Nonlinear Alfvén Waves In Space, T Hada, Robert L. Hamilton, C F. Kennel

Faculty Publications - Department of Mathematics

We apply the inverse scattering transform (1ST) based upon the Derivative Nonlinear Schrödinger (DNLS) equation to a complex time series of nonlinear Alfvén wave data generated by numerical simulation. The IST describes the long-time evolution of quasi-parallel Alfvén waves more efficiently than the Fourier transform, which is adapted to linear, not nonlinear, problems. When we add dissipation, so the conditions for the validity of the DNLS are not strictly satisfied, the IST continues to provide a compact description of the wavefield in terms of a small number of decaying envelope solitons. Since large amplitude Alfven waves and other nonlinear waves …

Alfvén Solitons And The Dnls Equation, Robert L. Hamilton, C F. Kennel, E Mjølhus

Faculty Publications - Department of Mathematics

No abstract provided.

Comptel Gamma Ray And Neutron Measurements Of Solar Flares, James M. Ryan, D J. Forrest, J Lockwood, M Loomis, Mark L. Mcconnell, D Morris, W Webber, G Rank, V Schonfelder, B Swanenburg, K Bennett, L O. Hanlon, C Winkler, H Debrunner

Space Science Center

COMPTEL on the Compton Gamma Ray Observatory has measured the flux of x‐rays and neutrons from several solar flares. These data have also been used to image the Sun in both forms of radiation. Unusually intense flares occurred during June 1991 yielding data sets that offer some new insight into of how energetic protons and electrons are accelerated and behave in the solar environment. We summarize here some of the essential features in the solar flare data as obtained by COMPTEL during June 1991.