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Aerospace, Physics, and Space Science Faculty Publications

Articles 241 - 266 of 266

Full-Text Articles in Astrophysics and Astronomy

Tip Of The Red Giant Branch Distances To Ngc 4214, Ugc 685, And Ugc 5456, Jesús Maíz Apellániz, Lucas Cieza, John W. Mackenty Mar 2002

Tip Of The Red Giant Branch Distances To Ngc 4214, Ugc 685, And Ugc 5456, Jesús Maíz Apellániz, Lucas Cieza, John W. Mackenty

Aerospace, Physics, and Space Science Faculty Publications

We have used WFPC2 VRI observations to calculate the distances to three nearby galaxies, NGC 4214, UGC 685, and UGC 5456, using the tip of the red giant branch method. Our values for NGC 4214 (2.94 ± 0.18 Mpc) and UGC 685 (4.79 ± 0.30 Mpc) are the most precise measurements of the distances to these objects ever made. For UGC 5456 the data do not allow us to reach a decisive conclusion since there are two possible solutions, one leading toward a short distance around 3.8 Mpc and another one toward a long distance of 5.6 Mpc or more.

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A New Heavy Ion Abundance Enrichment Pattern In ³He-Rich Solar Particle Events, Glenn M. Mason, Joseph E. Mazur, Joseph R. Dwyer Jan 2002

A New Heavy Ion Abundance Enrichment Pattern In ³He-Rich Solar Particle Events, Glenn M. Mason, Joseph E. Mazur, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

We report the first examples of ³He-rich solar energetic particle (SEP) events with heavy ion enrichments that are not ordered generally by mass. A second new feature is the large enrichment of ¹⁴N, the first time large enrichments have been seen for heavy ions lighter than O or Ne. These SEP events were too small and at too low an energy (<500 keV nucleon-1) to have been observed previously. The best observed event, 2001 July 16, had abundance ratios C : N : O : Ne : Mg : Si : S : Ca : Fe of ∼0.8 : 1.0 : ≡ 1 : 0.5 : 0.5 : 2.0 : 2.4 : 0.2 : 0.9, corresponding, respectively, to enhancements over the slow solar wind of ∼1.2 :15 : ≡ 1 : 5. : 3.4 : 12 :49 : 19 : 7. This pattern is incompatible with a gravitational settling enrichment mechanism. The simultaneous large enhancements of ¹⁴N and ²⁸Si, which have identical charge-to-mass ratios for certain ionization states, suggest that selective plasma wave heating plays a key role, as has long been suspected. Enhancement of ¹⁴N implies relatively low temperatures (<1.5 × 10 6 K) since fully stripped ¹⁴N cannot be preferentially heated. Also, the presence of enhanced species such as ¹⁴N and ²⁸Si, along with others with small or no enhancements ( 16)O, ²⁰Ne), may indicate that the plasma waves must operate over a relatively narrow range of frequencies and that the material must be heated while the waves are present.

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The Temporal Spectrum Of The Sdb Pulsating Star Hs 2201+2610 At 2 Ms Resolution, R Silvotti, T D. Oswalt, Nicole M. Silvestri, Glenn Carlson Jan 2002

The Temporal Spectrum Of The Sdb Pulsating Star Hs 2201+2610 At 2 Ms Resolution, R Silvotti, T D. Oswalt, Nicole M. Silvestri, Glenn Carlson

Aerospace, Physics, and Space Science Faculty Publications

In this article we present the results of more than 180 hours of time-series photometry on the low gravity (log g = 5.4, Teff = 29 300 K, log He/H = -3.0 by number) sdB pulsating star HS 2201+2610, obtained between September 2000 and August 2001. The temporal spectrum is resolved and shows 5 close frequencies: three main signals at 2860.94, 2824.10 and 2880.69 μHz, with amplitudes of about 1%, 0.5% and 0.1% respectively, are detected from single run observations; two further peaks with very low amplitude (<0.07%) at 2738.01 and 2921.82 μHz are confirmed by phase analysis on several independent runs. Due to the small number of detected frequencies, it is not possible to obtain a univocal identification of the excited modes and perform a detailed seismological analysis of the star. No clear signatures of rotational splitting are seen. Nevertheless, the observed period spectrum is well inside the excited period window obtained from pulsation calculations with nonadiabatic models having effective temperature and surface gravity close to the spectroscopic estimates. Due to its relatively simple temporal spectrum, HS 2201+2610 is a very good candidate for trying to measure the secular variation of the pulsation periods in time. With this purpose a long-term monitoring of the star was started. The results of the first 11 months show amplitude variations up to ∼20% on time-scales of months, which are probably real, and allow us to measure the pulsation frequencies with an unprecedented 0.02 μHz resolution.

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Asteroseismology Of Rxj 2117+3412, The Hottest Pulsating Pg 1159 Star, G Vauclair, Matt A. Wood Jan 2002

Asteroseismology Of Rxj 2117+3412, The Hottest Pulsating Pg 1159 Star, G Vauclair, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

The pulsating PG 1159 planetary nebula central star RXJ 2117+3412 has been observed over three successive seasons of a multisite photometric campaign. The asteroseismological analysis of the data, based on the 37 identified ℓ = 1 modes among the 48 independent pulsation frequencies detected in the power spectrum, leads to the derivation of the rotational splitting, the period spacing and the mode trapping cycle and amplitude, from which a number of fundamental parameters can be deduced. The average rotation period is 1.16 ± 0.05 days. The trend for the rotational splitting to decrease with increasing periods is incompatible with a …

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Isotopic Composition Of Solar Energetic Particle Events Measured By Advanced Composition Explorer/Uleis, Joseph R. Dwyer, Glenn M. Mason, Joseph E. Mazur, Robert E. Gold, Stamatios M. Krimigis, Eberhard S. Möbius, Mark A. Popecki Dec 2001

Isotopic Composition Of Solar Energetic Particle Events Measured By Advanced Composition Explorer/Uleis, Joseph R. Dwyer, Glenn M. Mason, Joseph E. Mazur, Robert E. Gold, Stamatios M. Krimigis, Eberhard S. Möbius, Mark A. Popecki

Aerospace, Physics, and Space Science Faculty Publications

Since its 1997 August launch, the Ultra Low Energy Isotope Spectrometer (ULEIS) on board the Advanced Composition Explorer (ACE) has observed a large number of solar energetic particle (SEP) events in the 0.4-3 MeV nucleonˉ¹ range. These events show remarkable variability of both the elemental and isotopic compositions, with ²²Ne/²⁰Ne varying, from event to event, by up to a factor of 10, Fe/O by up to a factor of 100, and ³He/⁴He by up to a factor of 104. In this paper we present new measurements of the ²²Ne/²⁰Ne, ²⁶Mg/²⁴Mg, and ³He/⁴He ratios at ∼ 1 MeV nucleonˉ¹ and compare …

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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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Multiband Microvariability Observations Of Bl Lacertae During The Outburst Of 1997, Sandra D. Clements, Michael T. Carini Jan 2001

Multiband Microvariability Observations Of Bl Lacertae During The Outburst Of 1997, Sandra D. Clements, Michael T. Carini

Aerospace, Physics, and Space Science Faculty Publications

BL Lac was observed in the V and R bands on 11 nights in 1997 July during a major optical outburst. It varied continuously, exhibiting nightly variations ranging from 0.1 to 0.6 mag. Over the course of the 11 nights, BL Lac was seen to vary by 1.8 R magnitudes. Color variations were also observed, with BL Lac becoming bluer as it brightened. The influence of variable seeing conditions on the observed variations was investigated. No correlation was found between the observed microvariability and the local seeing conditions.

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White Dwarfs In Common Proper Motion Binary Systems: Mass Distribution And Kinematics, Nicole M. Silvestri, Terry D. Oswalt, Matt A. Wood, Jonathan Allyn Smith, Iain Neill Reid, Edward M. Sión Jan 2001

White Dwarfs In Common Proper Motion Binary Systems: Mass Distribution And Kinematics, Nicole M. Silvestri, Terry D. Oswalt, Matt A. Wood, Jonathan Allyn Smith, Iain Neill Reid, Edward M. Sión

Aerospace, Physics, and Space Science Faculty Publications

We present the mass distribution, gravitational redshifts, radial velocities, and space motions of white dwarf stars in common proper motion binary systems. The mass distribution we derive for the 41 DA white dwarfs in this study has a mean of 0.68 ± 0.04 M⊙. This distribution has a slightly higher mean and larger dispersion than most previous white dwarf studies. We hypothesize that this is due to a higher fraction of cool (average Teff ~ 10,000 K), hence old, white dwarfs in our sample. Our results indicate that samples made up of predominantly cool, old white dwarf stars tend to …

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Asymptotic Analysis Of The Structure Of A Steady Planar Detonation: Review And Extension, William B. Bush, L. Krishnamurthy Apr 1999

Asymptotic Analysis Of The Structure Of A Steady Planar Detonation: Review And Extension, William B. Bush, L. Krishnamurthy

Aerospace, Physics, and Space Science Faculty Publications

The structure of a steady planar Chapman-Jouguet detonation, which is supported by a direct first-order one-step irreversible exothermic unimolecular reaction, subject to Arrhenius kinetics, is examined. Solutions are studied, by means of a limit-processexpansion analysis, valid for A, proportional to the ratio of the reaction rate to the flow rate, going to zero, and for β, proportional to the ratio of the activation temperature to the maximum flow temperature, going to infinity, with the product Aβ½ going to zero. The results, essentially in agreement with the Zeldovich-von Neumann-Dōring model, show that the detonation consists of (1) a three-region upstream shocklike …

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Time Series Energy Production In Smoothed Particle Hydrodynamics Accretion Disks: Superhumps In The Am Canum Venaticorum Stars, James C. Simpson, Matt A. Wood Oct 1998

Time Series Energy Production In Smoothed Particle Hydrodynamics Accretion Disks: Superhumps In The Am Canum Venaticorum Stars, James C. Simpson, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

The energy production time series of our purely hydrodynamic accretion disk simulations display remarkable similarities with the observed light curves of dwarf novae superhumps in general and the AM CVn stars in particular. The superhump period excess as a function of mass ratio agrees well with earlier theoretical and numerical results, and the amplitudes and relative phases of the harmonics in the power spectra agree well with the observations. The morphology of the mean pulse profile appears to be a useful predictor of system mass ratio. Our modified smoothed particle hydrodynamics code time symmetrizes the interparticle forces when individual time …

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Broadband Optical Observations Of Bl Lacertae During The 1997 Outburst, Terry D. Oswalt, Daniel Marshall, Tim Robishaw Jun 1998

Broadband Optical Observations Of Bl Lacertae During The 1997 Outburst, Terry D. Oswalt, Daniel Marshall, Tim Robishaw

Aerospace, Physics, and Space Science Faculty Publications

We present BVRI observations of BL Lacertae during its recent outburst. These observations, made during a 3 month period, cover a significant portion of the optical flare. The reduced data are displayed as light curves and broadband spectra. Changes in the spectral index are analyzed, and the results are compared with previous BL Lac observations. We find that the variations are simultaneous in the optical bands, but the higher frequency bands show a higher amplitude of variability. The spectral index is variable during the active period, and there is marginal evidence that the spectrum flattens as the source gets brighter.

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White Dwarf Cosmochronometry. I. Monte Carlo Simulations Of Proper-Motion And Magnitude-Limited Samples Using Schmidt's 1/Vmax Estimator, Matt A. Wood, Terry D. Oswalt Apr 1998

White Dwarf Cosmochronometry. I. Monte Carlo Simulations Of Proper-Motion And Magnitude-Limited Samples Using Schmidt's 1/Vmax Estimator, Matt A. Wood, Terry D. Oswalt

Aerospace, Physics, and Space Science Faculty Publications

Observationally, white dwarf stars are a remarkably homogeneous class with a minimum observed Teff ∼ 4000 K. Theoretically, the physics that determines their cooling timescales is relatively more straightforward than that which determines main-sequence evolutionary timescales. As a result, the white dwarf luminosity function has for the last decade been used as a probe of the age and star formation rate of the Galactic disk, providing an estimated local disk age of ∼ 10 Gyr with estimated total uncertainties of roughly 20%. A long-standing criticism of the technique is that the reality of the reported downturn in the luminosity function …

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Asteroseismology Of A Star Cooled By Neutrino Emission: The Pulsating Pre-White Dwarf Pg 0122 + 200, Marlea Sean O'Brien, Matt A. Wood Mar 1998

Asteroseismology Of A Star Cooled By Neutrino Emission: The Pulsating Pre-White Dwarf Pg 0122 + 200, Marlea Sean O'Brien, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

Observation of g-rnode pulsations in the variable pre-white dwarf (GW Virginis) stars provides a unique means to probe their interiors and to study the late stages of stellar evolution. Multisite campaigns have in several cases proved highly successful in decoding pre-white dwarf light curves. Three previous attempts to untangle the pulsation spectrum of the coolest GW Virginis star, PG 0122+200, confirmed the existence of multiple g-modes but left the fundamental period spacing and therefore the star's mass and luminosity in doubt. We present an analysis based on new observations of PG 0122+200 obtained during a Whole Earth Telescope (WET) campaign …

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Understanding The Cool Da White Dwarf Pulsator, G29-38, Scot J. Kleinman, Matt A. Wood Mar 1998

Understanding The Cool Da White Dwarf Pulsator, G29-38, Scot J. Kleinman, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and compositions, critical to understanding post-main-sequence evolution, along with their cooling rates, which will allow us to calibrate their ages directly. The most important set of white dwarf variables to measure are the oldest of the pulsators, the cool DA variables (DAVs), which have not been explored previously through asteroseismology due to their complexity and instability. Through a time-series photometry data set spanning 10 yr, we explore the pulsation spectrum of the cool …

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Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Xii. Ground-Based Monitoring Of 3c 390.3, Matthias Dietrich, T. D. Oswalt, Jun Tao Jan 1998

Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Xii. Ground-Based Monitoring Of 3c 390.3, Matthias Dietrich, T. D. Oswalt, Jun Tao

Aerospace, Physics, and Space Science Faculty Publications

Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-1995 are presented. The broadband fluxes (B, V, R, and I), the spectrophotometric optical continuum flux Fλ(5177 Å), and the integrated emission-line fluxes of Hα, Hβ, Hγ, He II λ15876, and He II A4686 all show a nearly monotonic increase with episodes of milder short-term variations superposed. The amplitude of the continuum variations increases with decreasing wavelength (4400-9000 Å). The optical continuum variations follow the variations in the ultraviolet and X-ray with time delays, measured from the centroids of the cross-correlation functions, typically around 5 days, but with uncertainties …

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White Dwarfs In Globular Clusters: Hubble Space Telescope Observations Of M4, Harvey B. Richer, Matt A. Wood Aug 1997

White Dwarfs In Globular Clusters: Hubble Space Telescope Observations Of M4, Harvey B. Richer, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258 white dwarfs (WDs) in the Galactic globular cluster M4. Fields at three radial distances from the cluster center were observed, and sizable WD populations were found in all three. The location of these WDs in the color-magnitude diagram, their mean mass of 0.51(±0.03) M⊙, and their luminosity function confirm basic tenets of stellar evolution theory and support the results from current WD cooling theory. The WDs are used to extend the cluster main-sequence mass function upward to stars that have already completed their nuclear evolution. The …

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Whole Earth Telescope Observations Of The Helium Interacting Binary Pg 1346+082 (Cr Bootis), Judith L. Provençal, Matt A. Wood May 1997

Whole Earth Telescope Observations Of The Helium Interacting Binary Pg 1346+082 (Cr Bootis), Judith L. Provençal, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

We present our analysis of 240 hr of white-light, high-speed photometry of the dwarf nova-like helium variable PG 1346+082 (CR Boo). We identify two frequencies in the low-state power spectrum, at 679.670 ± 0.004 μHz and 669.887 ± 0.008 μHz. The 679.670 μHz variation is coherent over at least a 2 week time span, the first demonstration of a phase-coherent photometric variation in any dwarf nova-like interacting binary white dwarf system. The high-state power spectrum contains a complex fundamental with a frequency similar, but not identical, to the low-state spectrum, and a series of harmonics not detected in low state. …

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Design Considerations For A Small Ultraviolet-Visible Space Telescope For Amateur And Professional Use, Donald Platt Jan 1997

Design Considerations For A Small Ultraviolet-Visible Space Telescope For Amateur And Professional Use, Donald Platt

Aerospace, Physics, and Space Science Faculty Publications

Presented is a preliminary design for a small ultraviolet- visible (uv-vis) sensitive space telescope. Included will be optical, sensor, and spacecraft subsystem design considerations. With recent advances in charge coupled device (CCD) technology it is now possible to build a space telescope system with wavelength sensitivity from 200 to 1000 nm. A main objective of this design is to keep costs to a minimum and use commercial off the shelf (COTS) components wherever possible. Such a low-cost system could provide a platform for studying such untested techniques as small space-based optical interferometry. The observatory could be open to a guest …

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The Δ Scuti Star Fg Virginis Ii. A Search For High Pulsation Frequencies, Michel Breger, Matt A. Wood Jan 1996

The Δ Scuti Star Fg Virginis Ii. A Search For High Pulsation Frequencies, Michel Breger, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

Although the δ Scuti and roAp variables occupy similar positions on and near the main sequence, δ Scuti variables pulsate with lower radial and nonradial overtones and lower frequencies. To test whether high frequencies (as found in the roAp stars) are also present in δ Scuti stars, a multisite campaign with the Whole Earth Telescope (WET) was carried out for the star FG Vir. The 96.7 hours of WET photometry were supplemented by measurements made with the Delta Scuti Network (DSN), because the DSN technique includes regular measurements of comparison stars and is better suited to monitoring the low frequencies …

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Hubble Space Telescope Observations Of Cool White Dwarf Stars: Detection Of New Species Of Heavy Elements, Harry Shipman, Terry D. Oswalt Mar 1995

Hubble Space Telescope Observations Of Cool White Dwarf Stars: Detection Of New Species Of Heavy Elements, Harry Shipman, Terry D. Oswalt

Aerospace, Physics, and Space Science Faculty Publications

Observations of cool white dwarf stars with the Hubble Space Telescope has uncovered a number of spectral features from previously unobserved species. In this paper we present the data on four cool white dwarfs. We present line identifications, equivalent width measurements, and brief summaries of the significance of our findings. The four stars observed are GD 40 (DBZ3), G 74-7 (DAZ), L 745-46A (DZ), and LDS 749 B (DBA). Many additional species of heavy elements were detected in GD 40 and G 74-7. In L 745-46A,while the detections are limited to Fe I, Fe II, and Mg II, the quality …

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Effects Of Aberrations On Spatially Modulated Fourier Transform Spectrometers, R Glenn Sellar, James Bruce Rafert Sep 1994

Effects Of Aberrations On Spatially Modulated Fourier Transform Spectrometers, R Glenn Sellar, James Bruce Rafert

Aerospace, Physics, and Space Science Faculty Publications

Spatially modulated Fourier transform spectrometers (FTS) have a throughput advantage over dispersive spectrometers, since an FTS does not require a slit in order to achieve spectral resolution. The traditional implementation of FTSs employs a scanning Michelson interferometer, but since this interferometer is temporally modulated, it is difficult or impossible to use with a target whose spatial and/or spectral signature is changing rapidly. The less common spatially modulated approach to FTS allows all spectral channels to be acquired simultaneously, but cylindrical optics are required to create an imaging version a FTS (IFTS). This combination of cylindrical and spherical optics, used to …

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Simultaneous Light And Radial Velocity Curve Solutions For U Cephei, James Bruce Rafert, N L. Markworth Aug 1991

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, …

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The Physical Properties Of Double Degenerate Common Proper Motion Binaries, Edward M. Sion, Terry D. Oswalt, James Liebert, Paul Hintsen Apr 1991

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, …

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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 Feb 1991

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 …

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Four Short-Period Algols, James Bruce Rafert Oct 1990

Four Short-Period Algols, James Bruce Rafert

Aerospace, Physics, and Space Science Faculty Publications

We have analyzed the light curves of four close binary star systems (BV 267, RU UMi, XZ CMi, and VV UMa) using the Wilson-Devinney differential corrections model. The present system geometries of these binaries is that of short-period, semi-detached systems with Roche lobe filling secondaries and main-sequence primaries. Differential coordinates in the mass-luminosity and mass-radius diagrams indicate that the secondary components lie near the main sequence, except in the case of BV 267. It is suggested that these systems are binaries with slightly overluminous and over-sized secondaries which have undergone case A mass transfer. This contention is supported by timing …

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One-Dimensional Three-Body Scattering Problem Used As A Testing Ground For The K-Matrix Method For Scattering Reactions Of Complex Systems, D. Rodjak, William Tobocman, Gaurav K. Tandon Oct 1972

One-Dimensional Three-Body Scattering Problem Used As A Testing Ground For The K-Matrix Method For Scattering Reactions Of Complex Systems, D. Rodjak, William Tobocman, Gaurav K. Tandon

Aerospace, Physics, and Space Science Faculty Publications

The scattering reactions of three equal-mass particles constrained to move in a straight line and interacting with each other via zero-range potentials have been analyzed on the basis of the extended R-matrix theory. The simplicity of the model facilitates an exposition of the complexities that result from the existence of rearrangement channels and from the possibility for breakup into three-body channels. The conventional expressions for the K matrix and the T matrix are derived on a rigorous basis. A practical method for approximating the continuum of three-body breakup channels by a discrete set is used to carry out a distorted-wave …

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