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Articles 1 - 30 of 101
Full-Text Articles in Physical Sciences and Mathematics
(Teff,Log G,[Fe/H]) Classification Of Low-Resolution Stellar Spectra Using Artificial Neural Networks, Shawn Snider, Yuan Qu, Carlos Allende Prieto, Ted Von Hippel, Timothy C. Beers, Christopher Sneden, David L. Lambert, Silvia Rossi
(Teff,Log G,[Fe/H]) Classification Of Low-Resolution Stellar Spectra Using Artificial Neural Networks, Shawn Snider, Yuan Qu, Carlos Allende Prieto, Ted Von Hippel, Timothy C. Beers, Christopher Sneden, David L. Lambert, Silvia Rossi
Publications
New generation large-aperture telescopes, multi-object spectrographs, and large format detectors are making it possible to acquire very large samples of stellar spectra rapidly. In this context, traditional star-by-star spectroscopic analysis are no longer practical. New tools are required that are capable of extracting quickly and with reasonable accuracy important basic stellar parameters coded in the spectra. Recent analyses of Artificial Neural Networks (ANNs) applied to the classification of astronomical spectra have demonstrated the ability of this concept to derive estimates of temperature and luminosity. We have adapted the back-propagation ANN technique developed by von Hippel et al. (1994) to predict …
A Transiting "51 Peg-Like" Planet, Gregory W. Henry, Geoffrey W. Marcy, R. Paul Butler, Steve Vogt
A Transiting "51 Peg-Like" Planet, Gregory W. Henry, Geoffrey W. Marcy, R. Paul Butler, Steve Vogt
Information Systems and Engineering Management Research Publications
Doppler measurements from Keck exhibit a sinusoidal periodicity in the velocities of the G0 dwarf HD 209458, having a semiamplitude of 81 m s-1 and a period of 3.5239 days, which is indicative of a "51 Peg-like" planet with a minimum mass (M sin i) of 0.62 MJup and a semimajor axis of 0.046 AU. Follow-up photometry reveals a drop of 0.017 mag at the predicted time (within the errors) of transit by the companion based on the velocities. This is the first extrasolar planet observed to transit its star. The radius of the planet derived …
Fundamental Plane Distances To Early-Type Field Galaxies In The South Equatorial Strip. I. The Spectroscopic Data, K. R. Müller, G. Wegner, S. Raychaudhury, W. Freudling
Fundamental Plane Distances To Early-Type Field Galaxies In The South Equatorial Strip. I. The Spectroscopic Data, K. R. Müller, G. Wegner, S. Raychaudhury, W. Freudling
Dartmouth Scholarship
Radial velocities and central velocity dispersions are derived for 238 E/S0 galaxies from medium-resolution spectroscopy. New spectroscopic data have been obtained as part of a study of the Fundamental Plane distances and peculiar motions of early-type galaxies in three selected directions of the South Equatorial Strip, undertaken in order to investigate the reality of large-scale streaming motion; results of this study have been reported in M\"uller $et$ $al.$ (1998). The new APM South Equatorial Strip Catalog (−17.5 < δ < +2.5) was used to select the sample of field galaxies in three directions: (1) 15h10 – 16h10; (2) 20h30 – 21h50; (3) 00h10 – 01h30. The spectra obtained have a median S/N per ̊A of 23, an in- strumental resolution (FWHM) of ∼ 4 ̊A, and the spectro- graph resolution (dispersion) is ∼ 100 km s−1. The Fourier cross-correlation method was used to derive the radial ve- locities and velocity dispersions. The velocity dispersions have been corrected for the size of the aperture and for the galaxy effective radius. Comparisons of the derived radial velocities with data from the literature show that our values are accurate to 40 km s−1. A comparison with results from Jørgensen et al. (1995) shows that the derived central velocity dispersion have an rms scatter of 0.036 in log σ. There is no offset relative to the velocity dispersions of Davies et al. (1987).
Peculiar Velocities Of Nonlinear Structure: Voids In Mcvittie Spacetime, Sakai, Nobuyuki, Haines, Paul
Peculiar Velocities Of Nonlinear Structure: Voids In Mcvittie Spacetime, Sakai, Nobuyuki, Haines, Paul
Dartmouth Scholarship
As a study of peculiar velocities of nonlinear structure, we analyze the model of a relativistic thin-shell void in the expanding universe. (1) Adopting McVittie (MV) spacetime as a background universe, we investigate the dynamics of an uncompensated void with negative MV mass. Although the motion itself is quite different from that of a compensated void, as shown by Haines & Harris (1993), the present peculiar velocities are not affected by MV mass. (2) We discuss how precisely the formula in the linear perturbation theory applies to nonlinear relativistic voids, using the results in (1) as well as the previous …
Creation Of An Ultracold Neutral Plasma, Scott D. Bergeson, T. C. Killian, S. Kulin, L. A. Orozco, C. Orzel, S. L. Rolston
Creation Of An Ultracold Neutral Plasma, Scott D. Bergeson, T. C. Killian, S. Kulin, L. A. Orozco, C. Orzel, S. L. Rolston
Faculty Publications
We report the creation of an ultracold neutral plasma by photoionization of laser-cooled xenon atoms. The charge carrier density is as high as 2×10^9 cm^-3, and the temperatures of electrons and ions are as low as 100 mK and 10 uK, respectively. Plasma behavior is evident in the trapping of electrons by the positive ion cloud when the Debye screening length becomes smaller than the size of the sample. We produce plasmas with parameters such that both electrons and ions are strongly coupled.
Wiyn Open Cluster Study. Ii. Ubvri Ccd Photometry Of The Open Cluster Ngc 188, Ata Sarajedini, Ted Von Hippel, Vera Kozhurina-Platais, Pierre Demarque
Wiyn Open Cluster Study. Ii. Ubvri Ccd Photometry Of The Open Cluster Ngc 188, Ata Sarajedini, Ted Von Hippel, Vera Kozhurina-Platais, Pierre Demarque
Publications
We present high-precision UBVRI CCD photometry of the old open cluster NGC 188. Our color-magnitude diagram extends from near the red giant branch tip to as faint as ~5 mag below the main-sequence turnoff. From an analysis of these data along with published photometry for M67, we draw the following conclusions: (1) From the UBV two-color diagram, we find a reddening of E(B ̶ V) = 0.04 ± 0.02 for M67 and E(B ̶ V) = 0.09 ± 0.02 for NGC 188. (2) Based on main-sequence fitting to solar abundance isochrones, the distance moduli …
Stellar Angular Diameters Of Late-Type Giants And Supergiants Measured With The Navy Prototype Optical Interferometer, Tyler E. Nordgren, M. E. Germain, J. A. Benson, D. Mozurkewich, Jeffrey J. Sudol, N. M. Elias Ii, Arsen R. Hajian, N. M. White, D. J. Hutter, K. J. Johnston, F. S. Gauss, J. T. Armstrong, T. A. Pauls, L. J. Rickard
Stellar Angular Diameters Of Late-Type Giants And Supergiants Measured With The Navy Prototype Optical Interferometer, Tyler E. Nordgren, M. E. Germain, J. A. Benson, D. Mozurkewich, Jeffrey J. Sudol, N. M. Elias Ii, Arsen R. Hajian, N. M. White, D. J. Hutter, K. J. Johnston, F. S. Gauss, J. T. Armstrong, T. A. Pauls, L. J. Rickard
Physics & Engineering Faculty Publications
No abstract provided.
Recent Laboratory Tests Of A Hard X-Ray Solar Flare Polarimeter, Mark L. Mcconnell, John R. Macri, M Mcclish, Jack Ryalls
Recent Laboratory Tests Of A Hard X-Ray Solar Flare Polarimeter, Mark L. Mcconnell, John R. Macri, M Mcclish, Jack Ryalls
Space Science Center
We report on the development of a Compton scatter polarimeter for measuring the linear polarization of hard X-rays (50 - 300 keV) from solar flares. Such measurements would be useful for studying the directivity (or beaming) of the electrons that are accelerated in solar flares. We initially used a simple prototype polarimeter to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. We have recently fabricated a science model based on a modular design concept that places a self-contained polarimeter module on the front-end of …
Dual Function Euv Multilayer Mirrors For The Image Mission, David D. Allred, R. Steven Turley, Matthew B. Squires
Dual Function Euv Multilayer Mirrors For The Image Mission, David D. Allred, R. Steven Turley, Matthew B. Squires
Faculty Publications
We have developed a new family of EUV multilayer mirror coatings using uranium. Using this approach we have coated a set of six mirrors for the EUV Imager, a component of the IMAGE mission. This mission is a Medium Explorer (MIDEX) program, which is scheduled for launch early in 2000. The EUV Imager will study the distribution of He+ in the Earth's plasmasphere by detecting its resonantly scattered emission at 30.4 nm (41 eV) and will produce images of the structure and dynamics of the cold plasma on a global scale. There is, however, a bright at 58.4 nm (21 …
Selective Excitation And Thermal Quenching Of The Yellow Luminescence Of Gan, John S. Colton, P. Y. Yu, K. L. Teo, E. R. Weber, P. Perlin, I. Grzegory, K. Uchida
Selective Excitation And Thermal Quenching Of The Yellow Luminescence Of Gan, John S. Colton, P. Y. Yu, K. L. Teo, E. R. Weber, P. Perlin, I. Grzegory, K. Uchida
Faculty Publications
We report the observation of narrower structures in the yellow luminescence of bulk and thin-film n-type GaN, using the technique of selective excitation. These fine structures exhibit thermal quenching associated with an activated behavior. We attribute these fine structures to phonons and electronic excitations of a shallow donor-deep acceptor complex, and determine its activation energy for delocalization. Our results suggest that in addition to distant donor-acceptor pairs, the yellow luminescence can also involve emission complexes of shallow donors and deep acceptors.
The Type Ia Supernova 1998bu In M96 And The Hubble Constant, Saurabh Jha, Peter M. Garnavich, Robert P. Kirshner, Peter Challis, Alicia M. Soderberg, Lucas M. Macri, John P. Huchra, Pauline Barmby, Elizabeth J. Barton, Perry Berlind, Warren R. Brown, Nelson Caldwell, Michael L. Calkins, Sheila J. Kannappan, Daniel M. Koranyi, Michael A. Pahre, Kenneth J. Rines, Krzysztof Z. Stanek, Robert P. Stefanik, Andrew H. Szentgyorgyi, Petri Vaisanen, Zhong Wang, Joseph M. Zajac, Adam G. Riess, Alexei V. Filippenko, Weidong Li, Maryam Modjaz, Richard R. Treffers, Carl W. Hergenrother, Eva K. Grebel, Patrick Seitzer, George H. Jacoby, Priscilla J. Benson, Akbar H. Rizvi '99, Laurence A. Marschall, Jeffrey D. Goldader, Matthew Beasley, William D. Vacca, Bruno Leibundgut, Jason Spyromilio, Brian P. Schmidt, Peter R. Wood
The Type Ia Supernova 1998bu In M96 And The Hubble Constant, Saurabh Jha, Peter M. Garnavich, Robert P. Kirshner, Peter Challis, Alicia M. Soderberg, Lucas M. Macri, John P. Huchra, Pauline Barmby, Elizabeth J. Barton, Perry Berlind, Warren R. Brown, Nelson Caldwell, Michael L. Calkins, Sheila J. Kannappan, Daniel M. Koranyi, Michael A. Pahre, Kenneth J. Rines, Krzysztof Z. Stanek, Robert P. Stefanik, Andrew H. Szentgyorgyi, Petri Vaisanen, Zhong Wang, Joseph M. Zajac, Adam G. Riess, Alexei V. Filippenko, Weidong Li, Maryam Modjaz, Richard R. Treffers, Carl W. Hergenrother, Eva K. Grebel, Patrick Seitzer, George H. Jacoby, Priscilla J. Benson, Akbar H. Rizvi '99, Laurence A. Marschall, Jeffrey D. Goldader, Matthew Beasley, William D. Vacca, Bruno Leibundgut, Jason Spyromilio, Brian P. Schmidt, Peter R. Wood
Physics and Astronomy Faculty Publications
We present optical and near-infrared photometry and spectroscopy of the Type Ia SN 1998bu in the Leo I Group galaxy M96 (NGC 3368). The data set consists of 356 photometric measurements and 29 spectra of SN 1998bu between UT 1998 May 11 and July 15. The well-sampled light curve indicates the supernova reached maximum light in B on UT 1998 May 19.3 (JD 2450952.8^0.8) with B\12.22^0.03 and V \11.88^0.02. Application of a revised version of the Multicolor Light Curve Shape (MLCS) method yields an extinction toward the supernova of AV\0.94^0.15 mag, and indicates the supernova was of average luminosity compared …
The Pulsation Properties Of Procyon A, Brian Chaboyer, P. Demarque, D. B. Guenther
The Pulsation Properties Of Procyon A, Brian Chaboyer, P. Demarque, D. B. Guenther
Dartmouth Scholarship
A grid of stellar evolution models for Procyon A has been calculated. These models include the best physics available to us (including the latest opacities and equation of state) and are based on the revised astrometric mass of Girard et al. Models were calculated with helium diffusion and with the combined effects of helium and heavy-element diffusion. Oscillation frequencies for l = 0, 1, 2, and 3 p-modes and the characteristic period spacing for the g-modes were calculated for these models. We find that g-modes are sensitive to model parameters that effect the structure of the core, …
Coded-Aperture X-Ray/Gamma-Ray Telescope For Arc-Minute Localization Of Gamma-Ray Bursts, M L. Cherry, P P. Altice, D L. Band, J Buckley, T G. Guzik, P L. Hink, S C. Kappadath, John R. Macri, J L. Matteson, Mark L. Mcconnell, Terence J. O'Neill, James M. Ryan, K R. Slavis, J G. Stacy, Allen Zych
Coded-Aperture X-Ray/Gamma-Ray Telescope For Arc-Minute Localization Of Gamma-Ray Bursts, M L. Cherry, P P. Altice, D L. Band, J Buckley, T G. Guzik, P L. Hink, S C. Kappadath, John R. Macri, J L. Matteson, Mark L. Mcconnell, Terence J. O'Neill, James M. Ryan, K R. Slavis, J G. Stacy, Allen Zych
Space Science Center
MARGIE will be a large-area, wide field-of-view, hard x- ray/gamma-ray imaging telescope capable of providing accurate positions for faint gamma-ray bursts in near-real- time and of performing a sensitive survey of both steady and transient cosmic sources. The instrument is designed to image faint bursts at the low-intensity end of the log N - log S distribution. MARGIE was recently selected by NASA for a mission-concept study for an Ultra Long Duration Balloon flight. We describe a program to develop an instrument based on the new detector technology of either cadmium zinc telluride room-temperature semiconductors or pixelated cesium iodide scintillators …
Fiberglast: A Scintillating Fiber Approach To The Glast Mission, Geoffrey N. Pendleton, W Robert Binns, Martin W. Israel, P L. Hink, M L. Cherry, W Paciesas, R M. Kippen, Robert S. Mallozzi, Thomas A. Parnell, Gerald J. Fishman, O T. Tumer, Mark J. Christl, Robert B. Wilson, J Buckley, Georgia A. Richardson, Surasak Phengchamnan, Keith R. Rielage, Gerald Karr, Donald B. Wallace, James M. Ryan, Mark L. Mcconnell, John R. Macri
Fiberglast: A Scintillating Fiber Approach To The Glast Mission, Geoffrey N. Pendleton, W Robert Binns, Martin W. Israel, P L. Hink, M L. Cherry, W Paciesas, R M. Kippen, Robert S. Mallozzi, Thomas A. Parnell, Gerald J. Fishman, O T. Tumer, Mark J. Christl, Robert B. Wilson, J Buckley, Georgia A. Richardson, Surasak Phengchamnan, Keith R. Rielage, Gerald Karr, Donald B. Wallace, James M. Ryan, Mark L. Mcconnell, John R. Macri
Space Science Center
FiberGLAST is a scintillating fiber gamma-ray detector designed for the GLAST mission. The system described below provides superior effective area and field of view for modest cost and risk. An overview of the FiberGLAST instrument is presented, as well as a more detailed description of the principle elements of the primary detector volume. The triggering and readout electronics are described, and Monte Carlo Simulations of the instrument performance are presented.
Beam Test Results For The Fiberglast Instrument, Robert S. Mallozzi, R M. Kippen, Geoffrey N. Pendleton, W Paciesas, Georgia A. Richardson, Surasak Phengchamnan, Gerald Karr, Donald B. Wallace, Gerald J. Fishman, Thomas A. Parnell, Robert B. Wilson, Mark J. Christl, W Robert Binns, P L. Hink, Martin W. Israel, Keith R. Rielage, John W. Epstein, Paul F. Dowkontt, J Buckley, James M. Ryan, John R. Macri, Mark L. Mcconnell, O T. Tumer, M L. Cherry, T G. Guzik, J G. Stacy, S C. Kappadath, Muzaffer Atac, Katsushi Arisaka, David B. Cline, Yuriy Pischalnikov
Beam Test Results For The Fiberglast Instrument, Robert S. Mallozzi, R M. Kippen, Geoffrey N. Pendleton, W Paciesas, Georgia A. Richardson, Surasak Phengchamnan, Gerald Karr, Donald B. Wallace, Gerald J. Fishman, Thomas A. Parnell, Robert B. Wilson, Mark J. Christl, W Robert Binns, P L. Hink, Martin W. Israel, Keith R. Rielage, John W. Epstein, Paul F. Dowkontt, J Buckley, James M. Ryan, John R. Macri, Mark L. Mcconnell, O T. Tumer, M L. Cherry, T G. Guzik, J G. Stacy, S C. Kappadath, Muzaffer Atac, Katsushi Arisaka, David B. Cline, Yuriy Pischalnikov
Space Science Center
The FiberGLAST scintillating fiber telescope is a large-area instrument concept for NASA's GLAST program. The detector is designed for high-energy gamma-ray astronomy, and uses plastic scintillating fibers to combine a photon pair tracking telescope and a calorimeter into a single instrument. A small prototype detector has been tested with high energy photons at the Thomas Jefferson National Accelerator Facility. We report on the result of this beam test, including scintillating fiber performance, photon track reconstruction, angular resolution, and detector efficiency.
Recent Progress In The Development Of A Solar Neutron Tracking Device (Sontrac), James M. Ryan, Wenhui Li, John R. Macri, Mark L. Mcconnell, Carlos Castaneda, Juan L. Romero
Recent Progress In The Development Of A Solar Neutron Tracking Device (Sontrac), James M. Ryan, Wenhui Li, John R. Macri, Mark L. Mcconnell, Carlos Castaneda, Juan L. Romero
Space Science Center
We report the results of recent calibration data analysis of a prototype scintillating fiber tracking detector system designed to perform imaging, spectroscopy and particle identification on 20 to 250 MeV neutrons and protons. We present the neutron imaging concept and briefly review the detection principle and the prototype description. The prototype detector system records ionization track data on an event-by-event basis allowing event selection criteria to be used in the off-line analysis. Images of acrylic phantoms from the analysis of recent proton beam calibrations are presented as demonstrations of the particle identification, imaging and energy measurement capabilities. The measured position …
Development And Testing Of A Fiber/Multianode Photomultiplier System For Use On Fiberglast, Keith R. Rielage, Katsushi Arisaka, Muzaffer Atac, W Robert Binns, J Buckley, M L. Cherry, Mark J. Christl, David B. Cline, Paul F. Dowkontt, John W. Epstein, Gerald J. Fishman, T G. Guzik, P L. Hink, Martin H. Israel, S C. Kappadath, Gerald Karr, R M. Kippen, Daniel Leopold, Mark L. Mcconnell, John R. Macri, Robert S. Mallozzi, W Paciesas, Thomas A. Parnell, Geoffrey N. Pendleton, Surasak Phengchamnan, Yuriy Pischalnikov, Georgia A. Richardson, James M. Ryan, J G. Stacy, O T. Tumer, Gerald J. Vissor, Donald B. Wallace, Robert B. Wilson
Development And Testing Of A Fiber/Multianode Photomultiplier System For Use On Fiberglast, Keith R. Rielage, Katsushi Arisaka, Muzaffer Atac, W Robert Binns, J Buckley, M L. Cherry, Mark J. Christl, David B. Cline, Paul F. Dowkontt, John W. Epstein, Gerald J. Fishman, T G. Guzik, P L. Hink, Martin H. Israel, S C. Kappadath, Gerald Karr, R M. Kippen, Daniel Leopold, Mark L. Mcconnell, John R. Macri, Robert S. Mallozzi, W Paciesas, Thomas A. Parnell, Geoffrey N. Pendleton, Surasak Phengchamnan, Yuriy Pischalnikov, Georgia A. Richardson, James M. Ryan, J G. Stacy, O T. Tumer, Gerald J. Vissor, Donald B. Wallace, Robert B. Wilson
Space Science Center
A scintillating fiber detector is currently being studied for the NASA Gamma-Ray Large Area Space Telescope (GLAST) mission. This detector utilizes modules composed of a thin converter sheet followed by an x, y plane of scintillating fibers to examine the shower of particles created by high energy gamma-rays interacting in the converter material. The detector is composed of a tracker with 90 such modular planes and a calorimeter with 36 planes. The two major component of this detector are the scintillating fibers and their associated photodetectors. Here we present current status of development and test result of both of these. …
Energy And Position Resolution Of A Cdznte Gamma-Ray Detector With Orthogonal Coplanar Anodes, O Tousignant, L A. Hamel, Pierre C. Dufour, F Joly, John R. Macri, Mark L. Mcconnell, James M. Ryan, V T. Jordanov
Energy And Position Resolution Of A Cdznte Gamma-Ray Detector With Orthogonal Coplanar Anodes, O Tousignant, L A. Hamel, Pierre C. Dufour, F Joly, John R. Macri, Mark L. Mcconnell, James M. Ryan, V T. Jordanov
Space Science Center
We report on the simulation, construction and performance of prototype CZT imaging detectors employing orthogonal coplanar anodes. These detectors employ a novel electrode geometry with non-collecting anode strips in 1D and collecting anode pixels, interconnected in rows, in the orthogonal dimensions. These detectors retain the spectroscopic and detection efficiency advantages of single carried charge sensing devices as well as the principal advantage of conventional strip detectors with orthogonal anode and cathode strips, i.e. an N X N array of imagin pixels are realized with only 2N electronic channels. Charge signals induced on the various electrodes of a prototype detector with …
Phonon And Elastic Instabilities In Moc And Mon, Gus L. W. Hart, Barry M. Klein
Phonon And Elastic Instabilities In Moc And Mon, Gus L. W. Hart, Barry M. Klein
Faculty Publications
We present several results related to the instability of MoC and MoN in the B1 (sodium chloride) structure. These compounds were proposed as potential superconductors with moderately high transition temperatures. We show that the elastic instability in B1-structure MoN, demonstrated several years ago, persists at elevated pressures, thus offering little hope of stabilizing this material without chemical doping. For MoC, another material for which stoichiometric fabrication in the B1 structure has not proven possible, we find that all of the cubic elastic constants are positive, indicating elastic stability. Instead, we find X-point phonon instabilities in MoC (and in MoN as …
Cross Sections Fall 1999, Department Of Physics And Astronomy
Cross Sections Fall 1999, Department Of Physics And Astronomy
Cross Sections
No abstract provided.
Simultaneous Photometry And Spectroscopy Of The Newly Discovered Γ Doradus Variable Hr 8330=Hd 207223, Anthony B. Kaye, Gregory W. Henry, Francis C. Fekel, Douglas S. Hall
Simultaneous Photometry And Spectroscopy Of The Newly Discovered Γ Doradus Variable Hr 8330=Hd 207223, Anthony B. Kaye, Gregory W. Henry, Francis C. Fekel, Douglas S. Hall
Information Systems and Engineering Management Research Publications
We present BV photometry and simultaneous high-resolution, high signal-to-noise ratio spectroscopy of the newly-discovered γ Doradus variable HR 8330 taken during the 1997 and 1998 observing seasons. We calculate power spectra for the B- and V-band data sets and for the time series defined throughout the observing season at each point across the Fe iiλ4508.289 and the Ti iiλ4501.278 line profiles to search for periodic variability. Period analysis reveals a single, 2.6-d period in both the photometric and the spectroscopic data, with a 237° phase lag between them. Based on the location of HR 8330 in the HR diagram and …
A Scintillating Plastic Fiber Tracking Detector For Neutron And Proton Imaging And Spectroscopy, James M. Ryan, John R. Macri, Mark L. Mcconnell, Richard A. Messner, Wenhui Li, Hansford H. Cutlip, Quihua Zheng, Carlos Castaneda, Juan L. Romero
A Scintillating Plastic Fiber Tracking Detector For Neutron And Proton Imaging And Spectroscopy, James M. Ryan, John R. Macri, Mark L. Mcconnell, Richard A. Messner, Wenhui Li, Hansford H. Cutlip, Quihua Zheng, Carlos Castaneda, Juan L. Romero
Space Science Center
We report the results of recent calibration data analysis of a prototype scintillating fiber tracking detector system designed to perform imaging, spectroscopy and particle identification on 20 to 250 MeV neutrons and protons. We present the neutron imaging concept and briefly review the detection principle and the prototype description. The prototype detector system records ionization track data on an event-by-event basis allowing event selection criteria to be used in the off-line analysis. Images of acrylic phantoms from the analysis of recent proton beam calibrations (14 to 65 MeV range) are presented as demonstrations of the particle identification, imaging and energy …
Hubble Space Telescope/Faint Object Spectrograph Spectroscopy Of Spatially Resolved Narrow-Line Regions In The Seyfert 2 Galaxies Ngc 2110 And Ngc 5929, Pierre Ferruit, Andrew S. Wilson, Mark Whittle, Chris Simpson, John S. Mulchaey, Gary J. Ferland
Hubble Space Telescope/Faint Object Spectrograph Spectroscopy Of Spatially Resolved Narrow-Line Regions In The Seyfert 2 Galaxies Ngc 2110 And Ngc 5929, Pierre Ferruit, Andrew S. Wilson, Mark Whittle, Chris Simpson, John S. Mulchaey, Gary J. Ferland
Physics and Astronomy Faculty Publications
We present the results of UV and optical Hubble Space Telescope/Faint Object Spectrograph spectroscopy of bright, extranuclear regions of line emission in the Seyfert galaxies NGC 2110 and NGC 5929. We have obtained spectra of the brightest region of the ``nuclear jet'' of NGC 2110 (75 pc from the nucleus) and of the southwest emission-line cloud of NGC 5929 (90 pc from the nucleus), in the G130H (1090-1605 Å), G190H (1570-2310 Å), G400H (3235-4780 Å), and G570H (4570-6820 Å) configurations. The observed line ratios are compared with the predictions of the two component (matter- and ionization-bounded, MB-IB), central source …
Stellar Masses, Kinematics, And White Dwarf Composition For Three Close Da+Dme Binaries, Stephane Vennes, John R. Thorstensen, Elisha F. Polomski
Stellar Masses, Kinematics, And White Dwarf Composition For Three Close Da+Dme Binaries, Stephane Vennes, John R. Thorstensen, Elisha F. Polomski
Dartmouth Scholarship
We determine the mass functions and mass ratios for three close white dwarf plus red dwarf binaries (EUVE J0720-317, 1016-053, and 2013+400). Hubble Space Telescope Goddard High-Resolution Spectrograph spectra of the He II λ1640 and C IV λ1550 spectral lines trace the white dwarf orbital motion, and Hamilton Spectrograph echelle spectra (Lick Observatory) and lower dispersion spectra trace the red dwarf orbital motion. The data sets allow us to measure orbital periods and velocities, as well as the white dwarf gravitational redshifts. The red dwarf and white dwarf mass estimates obtained from a combination of independent mass measurements for the …
Large‐Scale Power Spectrum And Cosmological Parameters From Sfi Peculiar Velocities, Wolfram Freudling, Idit Zehavi, Luiz N. Da Costa, Avishai Dekel, Amiram Eldar, Riccardo Giovanelli, Martha P. Haynes, John J. Salzer, Gary Wegner, Saleem Zaroubi
Large‐Scale Power Spectrum And Cosmological Parameters From Sfi Peculiar Velocities, Wolfram Freudling, Idit Zehavi, Luiz N. Da Costa, Avishai Dekel, Amiram Eldar, Riccardo Giovanelli, Martha P. Haynes, John J. Salzer, Gary Wegner, Saleem Zaroubi
Dartmouth Scholarship
We estimate the power spectrum of mass density fluctuations from peculiar velocities of galaxies by applying an improved maximum likelihood technique to the new all-sky SFI catalog. Parametric models are used for the power spectrum and the errors, and the free parameters are determined by assuming Gaussian velocity fields and errors and maximizing the probability of the data given the model. It has been applied to generalized cold dark matter (CDM) models with and without COBE normalization. The method has been carefully tested using artificial SFI catalogs. The most likely distance errors are found to be similar to the original …
Tracing Interactions In Hickson Compact Groups Through The Hi, L Verdes-Montenegro, Min S. Yun, B A. Williams, W K. Huchtmeier, A Del Olmo, J Perea
Tracing Interactions In Hickson Compact Groups Through The Hi, L Verdes-Montenegro, Min S. Yun, B A. Williams, W K. Huchtmeier, A Del Olmo, J Perea
Min S. Yun
We present a global study of HI spectral line mapping for 16 Hickson Compact Groups (HCGs) combining new and unpublished VLA data, plus the analysis of the HI content of individual galaxies. Sixty percent of the groups show morphological and kinematical signs of perturbations (from multiple tidal features to concentration of the HI in a single enveloping cloud) and sixty five of the resolved galaxies are found to be HI deficient with respect to a sample of isolated galaxies. In total, 77% of the groups suffer interactions among all its members which provides strong evidence of their reality. We find …
A Review Of Automated Stellar Spectral Classification And Surveys, Ted Von Hippel, Coryn A.L. Bailer-Jones
A Review Of Automated Stellar Spectral Classification And Surveys, Ted Von Hippel, Coryn A.L. Bailer-Jones
Publications
Modern spectroscopic surveys and automated classifiers are becoming so inextricably linked that it is difficult even to summarize one without discussing the other. Some of the automated classifiers are being built because of current analysis needs, though with a clear anticipation of future, larger surveys. Other automated classifiers are being designed specifically for future surveys. Automated classifiers may be applied to databases already in hand, to real-time analysis at the telescope, or one day to on-board satellite analysis where the raw data are too bulky to save and transmit. In addition, many current spectroscopic surveys target galaxies. These surveys may …
The Galactic Center Isolated Nonthermal Filaments As Analogs Of Cometary Plasma Tails, Steven N. Shore, Ted La Rosa
The Galactic Center Isolated Nonthermal Filaments As Analogs Of Cometary Plasma Tails, Steven N. Shore, Ted La Rosa
Faculty and Research Publications
We propose a model for the origin of the isolated nonthermal filaments observed at the Galactic center based on an analogy to cometary plasma tails. We invoke the interaction between a large-scale magnetized galactic wind and embedded molecular clouds. As the advected wind magnetic field encounters a dense molecular cloud, it is impeded and drapes around the cloud, ultimately forming a current sheet in the wake. This draped held is further stretched by the wind flow into a long, thin filament the aspect ratio of which is determined by the balance between the dynamical wind and amplified magnetic field pressures. …
Luminosity Profiles Of Merger Remnants, J E. Hibbard, Min S. Yun
Luminosity Profiles Of Merger Remnants, J E. Hibbard, Min S. Yun
Min S. Yun
Using published luminosity and molecular gas profiles of the late-stage mergers NGC 3921, NGC 7252, and Arp 220, we examine the expected luminosity profiles of the evolved merger remnants, especially in light of the massive CO complexes that are observed in their nuclei. For NGC 3921 and NGC 7252, we predict that the resulting luminosity profiles will be characterized by an r1/4 law. In view of previous optical work on these systems, it seems likely that they will evolve into normal elliptical galaxies as regards their optical properties. Due to a much higher central molecular gas column density, Arp 220 …
Detection Of Co (2-1) And Radio Continuum Emission From The Z = 4.4 Qso Bri 1335–0417, C L. Carilli, Karl M. Menten, Min S. Yun
Detection Of Co (2-1) And Radio Continuum Emission From The Z = 4.4 Qso Bri 1335–0417, C L. Carilli, Karl M. Menten, Min S. Yun
Min S. Yun
We have detected redshifted CO (2-1) emission at 43 GHz and radio continuum emission at 1.47 and 4.86 GHz from the z = 4.4 QSO BRI 1335-0417 using the Very Large Array. The CO data imply optically thick emission from warm (>30 K) molecular gas with a total mass, M(H2), of (1.5 ± 0.3) × 1011 Msun, using the standard Galactic gas mass-to-CO luminosity conversion factor. We set an upper limit to the CO source size of 1farcs1 and a lower limit of 0farcs23(Tex/50 K)-1/2, where Tex is the gas excitation temperature. We derive an upper limit to the …