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Articles 7861 - 7890 of 9206

Full-Text Articles in Physical Sciences and Mathematics

Terminal Speeds And Ion Fractions From [Caiv] 3.207 Μm In Three Single Wn Stars., Richard Ignace Sep 2001

Terminal Speeds And Ion Fractions From [Caiv] 3.207 Μm In Three Single Wn Stars., Richard Ignace

Richard Ignace

We report on the forbidden emission lines of [CaIV] at 3.207 μm and [NeIII] at 15.56 μm based on Infrared Space Observatory observations. The data set consists of three single Wolf-Rayet stars (WR 1, WR 134, and WR 136) and three binary systems (WR 11, WR 146, and WR 147). For the single stars, only the [CaIV] line was observed. Our primary objectives are to determine the wind terminal speed from the emission-line widths, derive ion number fractions, and discuss the relation between emission profile shapes and wind flow geometry. Compared to previous determinations of the terminal speed, we find …

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Large-Scale Power Spectrum And Structures From The Enear Galaxy Peculiar Velocity Catalogue, S. Zaroubi, M. Bernardi, L. N. Da Costa, Y. Hoffman, M. V. Alonso, G. Wegner Sep 2001

Large-Scale Power Spectrum And Structures From The Enear Galaxy Peculiar Velocity Catalogue, S. Zaroubi, M. Bernardi, L. N. Da Costa, Y. Hoffman, M. V. Alonso, G. Wegner

Dartmouth Scholarship

We estimate the mass density fluctuations power spectrum (PS) on large scales by applying a maximum likelihood technique to the peculiar velocity data of the recently completed redshift—distance survey of early-type galaxies (hereafter ENEAR). Parametric cold dark matter (CDM)-like models for the PS are assumed, and the best-fitting parameters are determined by maximizing the probability of the model given the measured peculiar velocities of the galaxies, their distances and estimated errors. The method has been applied to CDM models with and without COBE normalization. The general results are in agreement with the high-amplitude power spectra found from similar analyses of …

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The First Detection Of Coherent Emission From Radio Pulsars, F. A. Jenet, S. B. Anderson, T. A. Prince Sep 2001

The First Detection Of Coherent Emission From Radio Pulsars, F. A. Jenet, S. B. Anderson, T. A. Prince

Physics and Astronomy Faculty Publications and Presentations

The statistical properties of the radio emission from the pulsars B0823+26, B0950+08, B1133+16, and B1937+21 are studied using high time resolution observations taken at the Arecibo Observatory in Puerto Rico. Temporally coherent non-Gaussian emission has been detected in three of the four observed objects. This is the first time such a phenomenon has been observed. The results have been interpreted using a generalized shot noise model, and various basic physical quantities pertaining to the magnetospheric plasma have been estimated.

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Grb 010222: A Burst Within A Starburst, D. A. Frail, F. Bertoldi, G. H. Moriarty‐Schieven, E. Berger, P. A. Price, J. S. Bloom, R. Sari, S. R. Kulkarni, C. L. Gerardy, D. E. Reichart Aug 2001

Grb 010222: A Burst Within A Starburst, D. A. Frail, F. Bertoldi, G. H. Moriarty‐Schieven, E. Berger, P. A. Price, J. S. Bloom, R. Sari, S. R. Kulkarni, C. L. Gerardy, D. E. Reichart

Dartmouth Scholarship

We present millimeter and submillimeter wavelength observations and near-infrared K -band imaging toward the bright gamma-ray burst GRB 010222. Over seven epochs the flux density of the source was constant wit h an average flux density 3.74 ± 0.53 mJy at 350 GHz and 1.05 ± 0.22 mJy at 250 GHz, giving a spectral index α = 3 . 78 ± 0.25 (where F∝ να). We rule out the possibility that this emission originated from the burst or its afterglow and we conclu de that it is due to a dusty, high redshift starburst galaxy (SMM J14522+43 01). …

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Data Conditioning For Gravitational Wave Detectors: A Kalman Filter For Regressing Suspension Violin Modes, L. S. Finn, S. Mukherjee Aug 2001

Data Conditioning For Gravitational Wave Detectors: A Kalman Filter For Regressing Suspension Violin Modes, L. S. Finn, S. Mukherjee

Physics and Astronomy Faculty Publications and Presentations

Interferometric gravitational wave detectors operate by sensing the differential light travel time between free test masses. Correspondingly, they are sensitive to anything that changes the physical distance between the test masses, including physical motion of the masses themselves. In ground-based detectors the test masses are suspended as pendula, in order that they be approximately \"free\" above the pendulumn frequency. Still, thermal or other excitations of the suspension wires' violin modes do impart a force on the masses that appears as a strong, albeit narrow-band, \"signal\" in the detectors waveband. Gravitational waves, on the other hand, change the distance between the …

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Redshifts For 2410 Galaxies In The Century Survey Region, Gary Wegner, John R. Thorstensen, Michael J. Kurtz, Warren R. Brown, Daniel G. Fabricant, Margaret J. Geller, John P. Huchra, Ronald O. Marzke, Shoko Sakai Aug 2001

Redshifts For 2410 Galaxies In The Century Survey Region, Gary Wegner, John R. Thorstensen, Michael J. Kurtz, Warren R. Brown, Daniel G. Fabricant, Margaret J. Geller, John P. Huchra, Ronald O. Marzke, Shoko Sakai

Dartmouth Scholarship

The Century Survey strip covers 102 deg2 within the limits 85 ≤ α ≤ 165, 290 ≤ δ ≤ 300, equinox B1950.0. The strip passes through the Corona Borealis supercluster and the outer region of the Coma cluster. Within the Century Survey region, we have measured 2410 redshifts that constitute four overlapping complete redshift surveys: (1) 1728 galaxies with Kron-Cousins Rph ≤ 16.13 covering the entire strip, (2) 507 galaxies with Rph ≤ 16.4 in right ascension range 8h32m ≤ α ≤ 10 h45m, equinox B1950.0, (3) 1251 galaxies with absorption- …

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The Nature Of [Ar Iii]-Bright Knots In The Crab Nebula, Emily L. Schaller, Robert A. Fesen Aug 2001

The Nature Of [Ar Iii]-Bright Knots In The Crab Nebula, Emily L. Schaller, Robert A. Fesen

Dartmouth Scholarship

The kinematic and morphological properties of a string of [Ar III] bright knots in the CrabNebula are examined using 1994 – 1999 HST WFPC-2 images of the remnant. We find that five southern [Ar III] bright knots exhibit ordinary radial motions away from the nebula’s center of expansion with magnitudes consistent with their projected radial displacements. This result does not support the suggestion by MacAlpine et al. (1994) that these knots might be moving rapidly away from the Crab pulsar due to a collimated wind. The HST images also do not show that the [Ar III] knots have unusual morphologies …

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Statistics And Supermetallicity: The Metallicity Of Ngc 6791, B. J. Taylor Aug 2001

Statistics And Supermetallicity: The Metallicity Of Ngc 6791, B. J. Taylor

Faculty Publications

For the old galactic cluster NGC 6791, Peterson & Green (1998a) and Chaboyer et al. (1999) have found that [Fe/H] approximately + 0.4 dex. A second look at that conclusion is taken in this paper. Zero-point problems are reviewed for a high-dispersion analysis done by Peterson & Green, and it is found that accidental errors have not been determined rigorously for the results of that analysis. It is also noted that in a color-magnitude analysis performed by Chaboyer et al., the important metallicity range between 0.0 and + 0.3 dex is not explored and hence is not ruled out. Moreover, …

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Heavy‐Element Diffusion In Metal‐Poor Stars, Brian Chaboyer, W. H. Fenton, Jenica E. Nelan, D. J. Patnaude, Francesca E. Simon Aug 2001

Heavy‐Element Diffusion In Metal‐Poor Stars, Brian Chaboyer, W. H. Fenton, Jenica E. Nelan, D. J. Patnaude, Francesca E. Simon

Dartmouth Scholarship

Stellar evolution models that include the effect of helium and heavy-element diffusion have been calculated for initial iron abundances of [Fe/H] = -2.3, -2.1, -1.9, and -1.7. These models were calculated for a large variety of masses and three separate mixing lengths, α = 1.50, 1.75, and 2.00 (with α = 1.75 being the solar calibrated mixing length). The change in the surface iron abundance for stars of different masses was determined for the ages of 11, 13, and 15 Gyr. Iron settles out of the surface convection zone on the main sequence ; this iron is dredged back up …

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Chromospherically Active Stars. Xix. A Reexamination Of The Variability Of Hd 10909=Uv Fornacis, Francis C. Fekel, Gregory W. Henry, Keinon Brooks, Douglas S. Hall Aug 2001

Chromospherically Active Stars. Xix. A Reexamination Of The Variability Of Hd 10909=Uv Fornacis, Francis C. Fekel, Gregory W. Henry, Keinon Brooks, Douglas S. Hall

Information Systems and Engineering Management Research Publications

We have obtained new spectroscopy and photometry of the K0 IV, chromospherically active, single-lined spectroscopic binary HD 10909. Those observations show that the previously reported orbital and light variability periods are incorrect. HD 10909 has an orbital period of 30.1067 days and an eccentricity of 0.499. Its rotation period of 64.1 days is more than twice as long as its orbital period. The primary is situated near the base of the first-ascent red giant branch. Thus, its asynchronous rotation is likely the result of its recent evolution through the Hertzsprung gap, combined with its relatively long orbital period and high …

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Measurement And Interpretation Of Deuterium-Line Emission In The Orion Nebula, C. R. O'Dell, Gary J. Ferland, W. J. Henney Jul 2001

Measurement And Interpretation Of Deuterium-Line Emission In The Orion Nebula, C. R. O'Dell, Gary J. Ferland, W. J. Henney

Physics and Astronomy Faculty Publications

We present new observations of the deuterium and hydrogen Balmer lines in the Orion Nebula. There is a real variation in the deuterium-to-hydrogen line ratios across the nebula, being greatest in the emission from the largest proplyd (Orion 244-440). We also present the results of a detailed model for the emission of these lines, the hydrogen lines being the result of photoionization and recombination while the deuterium lines are produced by fluorescent excitation of the upper energy states by the far-UV radiation from θ1 Ori C. Comparison of the observations and predictions of the line intensities shows good agreement, …

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Three-Dimensional Spectral Classification Of Low-Metallicity Stars Using Artificial Neural Networks, Shawn Snider, Ted Von Hippel, Carlos Allende Prieto, Timothy C. Beers, Christopher Sneden, Et Al. Jul 2001

Three-Dimensional Spectral Classification Of Low-Metallicity Stars Using Artificial Neural Networks, Shawn Snider, Ted Von Hippel, Carlos Allende Prieto, Timothy C. Beers, Christopher Sneden, Et Al.

Publications

We explore the application of artificial neural networks (ANNs) for the estimation of atmospheric parameters (Teff, log g, and [Fe/H]) for Galactic F- and G-type stars. The ANNs are fed with medium-resolution (Δλ ~ 1-2 Å) non-flux-calibrated spectroscopic observations. From a sample of 279 stars with previous high-resolution determinations of metallicity and a set of (external) estimates of temperature and surface gravity, our ANNs are able to predict Teff with an accuracy of σ(Teff) = 135-150 K over the range 4250 ≤ Teff ≤ 6500 K, log g with an accuracy of σ(log …

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X‐Ray–Emitting Groups In The Infall Region Of Abell 2199, K. Rines, A. Mahdavi, M. J. Geller, A. Diaferio, J. J. Mohr, G. Wegner Jul 2001

X‐Ray–Emitting Groups In The Infall Region Of Abell 2199, K. Rines, A. Mahdavi, M. J. Geller, A. Diaferio, J. J. Mohr, G. Wegner

Dartmouth Scholarship

Using a large redshift survey covering 95 deg2, we demonstrate that the infall region of Abell 2199 contains Abell 2197, one or two X-ray-emitting groups, and up to five additional groups identified in redshift surveys. Our survey shows that the X-ray-emitting systems, located at projected radii of 14, 19, and 51 (2.2, 3.1, and 8.0 h-1 Mpc), are connected kinematically to A2199. A2197 is itself an optically rich cluster; its weak X-ray emission suggests that it is much less massive than A2199. The absence of a sharp peak in the infall pattern at the position of A2197 supports this …

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Stellar Pollution In The Solar Neighborhood, N. Murray, B. Chaboyer, P. Arras, B. Hansen, R. W. Noyes Jul 2001

Stellar Pollution In The Solar Neighborhood, N. Murray, B. Chaboyer, P. Arras, B. Hansen, R. W. Noyes

Dartmouth Scholarship

We study spectroscopically determined iron abundances of 640 solar-type stars to search for the signature of accreted iron-rich material. We find that the metallicity [Fe/H] of a subset of 466 main-sequence stars, when plotted as a function of stellar mass, mimics the pattern seen in lithium abundances in open clusters. Using Monte Carlo models, we find that, on average, these stars appear to have accreted ~0.5 M⊕ of iron while on the main-sequence. A consistency check is provided by a much smaller sample of 19 stars in the Hertzsprung gap, which are slightly evolved and the convection zones of …

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Shortcuts In The Fifth Dimension, Robert Caldwell, David Langlois Jul 2001

Shortcuts In The Fifth Dimension, Robert Caldwell, David Langlois

Dartmouth Scholarship

If our Universe is a three-brane embedded in a five-dimensional anti-de Sitter spacetime, in which matter is confined to the brane and gravity inhabits an infinite bulk space, then the causal propagation of luminous and gravitational signals is in general different. A gravitational signal traveling between two points on the brane can take a “shortcut” through the bulk, and appear quicker than a photon traveling between the same two points along a geodesic on the brane. Similarly, in a given time interval, a gravitational signal can propagate farther than a luminous signal. We quantify this effect, and analyze the impact …

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The Expansion Center And Dynamical Age Of The Galactic Supernova Remnant Cassiopeia A, John R. Thorstensen, Robert A. Fesen, Sidney Van Den Bergh Jul 2001

The Expansion Center And Dynamical Age Of The Galactic Supernova Remnant Cassiopeia A, John R. Thorstensen, Robert A. Fesen, Sidney Van Den Bergh

Dartmouth Scholarship

We present proper motions for 21 bright main shell and 17 faint, higher velocity, outer ejecta knots in the Cas A supernova remnant and use them to derive new estimates for the remnant's expansion center and age. Our study included 1951–1976 Palomar 5 m prime focus plates, 1988–1999 CCD images from the KPNO 4 m and MDM 2.4 m telescopes, and 1999 HST WFPC2 images. Measurable positions covered a 23 to 41 yr time span for most knots, with a few outer knots followed for almost 48 yr. We derive an expansion center of α(J2000) = 23h23m …

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Modelling X-Ray Variability In The Structured Atmospheres Of Hot Stars., L. M. Oskinova, R. Ignace, J. C. Brown, J. P. Cassinelli Jun 2001

Modelling X-Ray Variability In The Structured Atmospheres Of Hot Stars., L. M. Oskinova, R. Ignace, J. C. Brown, J. P. Cassinelli

Richard Ignace

We describe X-ray production in the atmospheres of hot, early-type stars in the framework of a "stochastic shock model". The extended envelope of a star is assumed to possess numerous X-ray emitting "hot" zones that are produced by shocks and embedded in the ambient "cold" medium in dynamical equilibrium. It is shown that the apparent lack of X-ray variability on short (similar to hours) timescales do not contradict a shock model for X-ray production. The character of the X-ray variability is found to depend on the frequency with which hot zones are generated, the cool wind opacity to X-rays, and …

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The Peculiar Motions Of Early-Type Galaxies In Two Distant Regions - Vi. The Maximum-Likelihood Gaussian Algorithm, M. Colless, R. P. Saglia, D. Burstein, R. L. Davies, R. K. Mcmahan, G. Wegner Jun 2001

The Peculiar Motions Of Early-Type Galaxies In Two Distant Regions - Vi. The Maximum-Likelihood Gaussian Algorithm, M. Colless, R. P. Saglia, D. Burstein, R. L. Davies, R. K. Mcmahan, G. Wegner

Dartmouth Scholarship

The EFAR project is designed to measure the properties and peculiar motions of early-type galaxies in two distant regions. Here we describe the maximum-likelihood algorithm we developed to investigate the correlations between the parameters of the EFAR data base. One-, two- and three-dimensional Gaussian models are constructed to determine the mean value and intrinsic spread of the parameters, and the slopes and intrinsic parallel and orthogonal spread of the Mg2–Mgb′,Mg2–σ,Mgb′–σ relations, and the Fundamental Plane. In the latter case, the cluster peculiar velocities are also determined. We show that this method is superior to …

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Chandra Detection Of Doppler-Shifted X-Ray Line Profiles From The Wind Of Zeta Puppis (O4f), J. P. Cassinelli, N. A. Miller, W. L. Waldron, J. J. Macfarlane, David H. Cohen Jun 2001

Chandra Detection Of Doppler-Shifted X-Ray Line Profiles From The Wind Of Zeta Puppis (O4f), J. P. Cassinelli, N. A. Miller, W. L. Waldron, J. J. Macfarlane, David H. Cohen

Physics & Astronomy Faculty Works

We report on a 67 ks High-Energy Transmission Grating observation of the optically brightest early O star zeta Puppis (O4 f). Many resolved X-ray lines are seen in the spectra over a wavelength range of 5-25 Angstrom. Chnndra has sufficient spectral resolution to study the velocity structure of isolated X-ray line profiles and to distinguish the individual forbidden, intercombination, and resonance (fir) emission lines in several He-like ions, even where the individual components are strongly Doppler-broadened. In contrast to X-ray line profiles in other hot stars, zeta Pup shows blueshifted and skewed line profiles, providing the dearest and most direct …

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The Peculiar Motions Of Early-Type Galaxies In Two Distant Regions -- Vii. Peculiar Velocities And Bulk Motions, Matthew Colless, R. P. Saglia, David Burstein, Roger L. Davies, Robert K. Mcmahan Jr, Gary Wegner May 2001

The Peculiar Motions Of Early-Type Galaxies In Two Distant Regions -- Vii. Peculiar Velocities And Bulk Motions, Matthew Colless, R. P. Saglia, David Burstein, Roger L. Davies, Robert K. Mcmahan Jr, Gary Wegner

Dartmouth Scholarship

We present peculiar velocities for 85 clusters of galaxies in two large volumes at distances between 6000 and 15 000 km s−1 in the directions of Hercules-Corona Borealis and Perseus-Pisces-Cetus (the EFAR sample). These velocities are based on Fundamental Plane (FP) distance estimates for early-type galaxies in each cluster. We fit the FP using a maximum likelihood algorithm which accounts for both selection effects and measurement errors, and yields FP parameters with smaller bias and variance than other fitting procedures. We obtain a best-fitting FP with coefficients consistent with the best existing determinations. We measure the bulk motions of …

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Acceleration Of ³He Nuclei At Interplanetary Shocks, Mihir I. Desai, Glenn M. Mason, Joseph R. Dwyer, Joseph E. Mazur, Charles W. Smith, Ruth M. Skoug May 2001

Acceleration Of ³He Nuclei At Interplanetary Shocks, Mihir I. Desai, Glenn M. Mason, Joseph R. Dwyer, Joseph E. Mazur, Charles W. Smith, Ruth M. Skoug

Aerospace, Physics, and Space Science Faculty Publications

We have surveyed the 0.5-2.0 MeV nucleonˉ¹ ion composition of 56 interplanetary (IP) shocks observed with the Ultra - Low-Energy Isotope Spectrometer on board the Advanced Composition Explorer from 1997 October 1 through 2000 November 30. Our results show the first ever measurement (25 cases) of ³He ions being accelerated at IP shocks. The ³He/⁴He ratio at the 25 shocks exhibited a wide range of values between 0.0014 and 0.24; the ratios were enhanced between factors of ∼3 and 600 over the solar wind value. During the survey period, the occurrence probability of ³He-rich shocks increased with rising solar activity …

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Formation Of Rydberg Atoms In An Expanding Ultracold Neutral Plasma, Scott D. Bergeson, T. C. Killian, M. J. Lim, S. Kulin, R. Dumke, S. L. Rolston Apr 2001

Formation Of Rydberg Atoms In An Expanding Ultracold Neutral Plasma, Scott D. Bergeson, T. C. Killian, M. J. Lim, S. Kulin, R. Dumke, S. L. Rolston

Faculty Publications

We study the formation of Rydberg atoms in expanding plasmas at temperatures of 1–1000 K and densities from 10^5–10^10 cm^-3. Up to 20% of the initially free charges recombine in about 100 us, and the binding energy of the Rydberg atoms approximately equals the increase in the kinetic energy of the remaining free electrons. Three-body recombination is expected to dominate in this regime, yet most of our results are inconsistent with this mechanism.

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What Determines The Emission Peak Energy Of The Blue Luminescence In Highly Mg-Doped P-Gan?, John S. Colton, P. Y. Yu Apr 2001

What Determines The Emission Peak Energy Of The Blue Luminescence In Highly Mg-Doped P-Gan?, John S. Colton, P. Y. Yu

Faculty Publications

We report a study of the 2.8 eV blue luminescence (BL) in heaviliy Mg-doped p-GaN via resonant excitation with a tunable blue dye laser. The dependence of the BL on the excitation photon energy (Eex) is unlike that of the yellow luminescence found in n-type GaN. An Urbach-type band tail, with Urbach parameter of 33 meV is observed in the vicinity of the BL energy. We propose that the peak energy of the BL marks the transition from localized states to delocalized states within this band tail.

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Helium Emission From Classical T Tauri Stars: Dual Origin In Magnetospheric Infall And Hot Wind, Georgina Beristain, Suzan Edwards, John Kwan Apr 2001

Helium Emission From Classical T Tauri Stars: Dual Origin In Magnetospheric Infall And Hot Wind, Georgina Beristain, Suzan Edwards, John Kwan

Astronomy: Faculty Publications

High-resolution emission-line profiles of He I and He II in 31 classical T Tauri stars are analyzed with the aim of probing the environs of the star-disk interface in accreting low-mass young stars. The diagnostic power of the helium lines lies in their high-excitation potentials, which restrict their formation to a region either of high temperature or close proximity to a source of ionizing radiation. The He I profiles are decomposed into kinematic components that support the paradigm of magnetically controlled accretion from the disk onto the stellar surface but also require a significant contribution from a hot wind. A …

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Affinity For Scalar Fields To Dissipate, Arjun Berera, Rudnei O. Ramos Apr 2001

Affinity For Scalar Fields To Dissipate, Arjun Berera, Rudnei O. Ramos

Dartmouth Scholarship

The zero-temperature effective equation of motion is derived for a scalar field interacting with other fields. For a broad range of cases, involving interaction with as few as one or two fields, dissipative regimes are found for the scalar field system. The zero-temperature limit constitutes a baseline effect that will be prevalent in any general statistical state. Thus, the results found here provide strong evidence that dissipation is the norm not the exception for an interacting scalar field system. For application to inflationary cosmology, this provides convincing evidence that warm inflation could be a natural dynamics once proper treatment of …

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First Results From The Anglo-Australian Planet Search: A Brown Dwarf Candidate And A 51 Peg-Like Planet, Chris G. Tinney, R. Paul Butler, Geoffrey W. Marcy, Hugh R. A. Jones, Alan J. Penny, Steve S. Vogt, Kevin Apps, Gregory W. Henry Apr 2001

First Results From The Anglo-Australian Planet Search: A Brown Dwarf Candidate And A 51 Peg-Like Planet, Chris G. Tinney, R. Paul Butler, Geoffrey W. Marcy, Hugh R. A. Jones, Alan J. Penny, Steve S. Vogt, Kevin Apps, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We report results from the Anglo-Australian Planet Search, a survey for planets around 200 solar-type stars in the southern hemisphere that is being carried out on the 3.9 m Anglo-Australian Telescope. Limiting Doppler precisions of 3 m s-1 have been demonstrated from the first 2.5 years of operation, making this the highest-precision planet search in the southern hemisphere. From these data we report results for two new substellar detections. The first is a 51 Peg-like planet around the star HD 179949 with M sin i = 0.84 MJUP. Photometric study reveals this is not a transiting system. The second is …

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A Search For Previously Unrecognized Metal-Poor Subdwarfs In The Hipparcos Astrometric Catalogue, I. N. Reid, F. Van Wyk, F. Marang, G. Roberts, D. Kilkenny, S. Mahoney Apr 2001

A Search For Previously Unrecognized Metal-Poor Subdwarfs In The Hipparcos Astrometric Catalogue, I. N. Reid, F. Van Wyk, F. Marang, G. Roberts, D. Kilkenny, S. Mahoney

Dartmouth Scholarship

We have identified 317 stars included in the Hipparcos astrometric catalogue that have parallaxes measured to a precision of better than 15 per cent, and the location of which in the (MV,(B−V)T) diagram implies a metallicity comparable to or less than that of the intermediate‐abundance globular cluster M5. We have undertaken an extensive literature search to locate Strömgren, Johnson/Cousins and Walraven photometry for over 120 stars. In addition, we present new UBV(RI)C photometry of 201 of these candidate halo stars, together with similar data for a further 14 known metal‐poor subdwarfs. These …

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Infrared Spectroscopy Of Symbiotic Stars. Iii. First Orbits For Three S-Type Systems, Francis C. Fekel, Kenneth H. Hinkle, Richard Joyce, Michael F. Skrutskie Apr 2001

Infrared Spectroscopy Of Symbiotic Stars. Iii. First Orbits For Three S-Type Systems, Francis C. Fekel, Kenneth H. Hinkle, Richard Joyce, Michael F. Skrutskie

Information Systems and Engineering Management Research Publications

Infrared radial velocities have been used to derive the first well-determined orbital elements for the cool giants of three symbiotic systems, BF Cyg, V1329 Cyg, and V343 Ser=AS 289. Periods found for BF Cyg and V1329 Cyg from the radial velocity data are in good agreement with periods previously determined for their light variations, and the orbits are circular. Masses for the components of BF Cyg and V1329 Cyg were determined by combining our orbital elements for the cool giants with elements for their hot stars. BF Cyg and V1329 Cyg are shown to be detached binary systems. The third …

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Cross Sections Spring 2001, Department Of Physics And Astronomy Apr 2001

Cross Sections Spring 2001, Department Of Physics And Astronomy

Cross Sections

No abstract provided.

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Geocoronal H-A [Alpha] Intensity Measurements Using The Wisconsin H-A [Alpha] Mapper Fabry-Perot Facility, S. Nossal, F. L. Roesler, J. Bishop, R. J. Reynolds, M. Haffner, S. Tufte, J. Percival, E. J. Mierkiewicz Apr 2001

Geocoronal H-A [Alpha] Intensity Measurements Using The Wisconsin H-A [Alpha] Mapper Fabry-Perot Facility, S. Nossal, F. L. Roesler, J. Bishop, R. J. Reynolds, M. Haffner, S. Tufte, J. Percival, E. J. Mierkiewicz

Physical Sciences - Daytona Beach

"The Wisconsin H-a [alpha] Mapper (WHAM), a remotely operable, semi-automated Fabry-Perot located at Kitt Peak Observatory, has been making an all-sky survey of interstellar hydrogen Balmer a [alpha] (H-a [alpha]) emissions since 1997. Using the annular summing spectroscopy technique, WHAM has acquired ~[approx.] 37,000 spectra to date, spanning almost 100 nights of observations. Since all of the galactic emission spectral data contain the terrestrial H-a [alpha] (6562.7 Å) emission line, these measurements constitute a rich source of geocoronal data for investigating natural variability in the upper atmosphere. The WHAM observations also serve as a benchmark for comparison with future …

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