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2006

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Articles 91 - 120 of 179

Full-Text Articles in Astrophysics and Astronomy

Joint Ligo And Tama300 Search For Gravitational Waves From Inspiralling Neutron Star Binaries, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Cristina V. Torres May 2006

Joint Ligo And Tama300 Search For Gravitational Waves From Inspiralling Neutron Star Binaries, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Cristina V. Torres

Physics & Astronomy Faculty Publications

We search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003. Using a simple trigger exchange method, we perform an intercollaboration coincidence search during times when TAMA300 and only one of the LIGO sites were operational. We find no evidence of any gravitational wave signals. We place an observational upper limit on the rate of binary neutron star coalescence with component masses between 1 and 3M⊙ of 49 per year per Milky Way equivalent galaxy at a 90% confidence level. The methods developed during this search will find application in …

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A Far-Ultraviolet Study Of The Hot White Dwarf In The Dwarf Nova Ww Ceti, Patrick Godon, Laura Seward, Edward M. Sion, Paula Szkody May 2006

A Far-Ultraviolet Study Of The Hot White Dwarf In The Dwarf Nova Ww Ceti, Patrick Godon, Laura Seward, Edward M. Sion, Paula Szkody

Aerospace, Physics, and Space Science Faculty Publications

We present a synthetic spectral analysis of IUE archival and FUSE (Far Ultraviolet Spectroscopic Explorer) far-UV spectra of the peculiar dwarf nova WW Cet. During the quiescence of WW Cet, a white dwarf with T wd ∼ 26,000 ± 1000 K can account for the far-UV flux and yields the proper distance. However, the best agreement with the observations is provided by a two-temperature white dwarf model with a cooler white dwarf at T wd = 25,000 K providing 75% of the far-UV flux and a hotter region (accretion belt or optically thick disk ring) with T = 40,000 K …

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Microlensing Of Circumstellar Envelopes Iii. Line Profiles From Stellar Winds In Homologous Expansion., M. Hendry, Richard Ignace, H. Bryce May 2006

Microlensing Of Circumstellar Envelopes Iii. Line Profiles From Stellar Winds In Homologous Expansion., M. Hendry, Richard Ignace, H. Bryce

ETSU Faculty Works

This paper examines line profile evolution due to the linear expansion of circumstellar material obsverved during a microlensing event. This work extends our previous papers on emission line profile evolution from radial and azimuthal flow during point mass lens events and fold caustic crossings. Both “flavours” of microlensing were shown to provide effective diagnostics of bulk motion in circumstellar envelopes. In this work a different genre of flow is studied, namely linear homologous expansion, for both point mass lenses and fold caustic crossings. Linear expansion is of particular relevance to the effects of microlensing on supernovae at cosmological distances. We …

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Origin Of The Turbulent Spectra In The High-Altitude Cusp: Cluster Spacecraft Observations, K. Nykyri, B. Grison, P. J. Cargill, B. Lavraud, E. Lucek, I. Dandouras, A. Balogh, N. Cornilleau-Wehrlin, H. Reme May 2006

Origin Of The Turbulent Spectra In The High-Altitude Cusp: Cluster Spacecraft Observations, K. Nykyri, B. Grison, P. J. Cargill, B. Lavraud, E. Lucek, I. Dandouras, A. Balogh, N. Cornilleau-Wehrlin, H. Reme

Publications

High-resolution magnetic field data from Cluster Flux GateMagnetometer (FGM) and the Spatio-Temporal Analysis of Field Fluctuations (STAFF) instruments are used to study turbulent magnetic field fluctuations during the highaltitude cusp crossing on 17 March 2001. Despite the quiet solar wind conditions, the cusp was filled with magnetic field turbulence whose power correlates with the field-aligned ion plasma flux. The magnetic field wave spectra shows power law behavior with both double and single slopes with break in the spectra usually occurring in the vicinity of the local ion cyclotron frequency. Strong peaks in the wave power close to local ion cyclotron …

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High-Resolution Optical Velocity Fields Of 11 Low Surface Brightness Galaxies, Stacy S. Mcgaugh Apr 2006

High-Resolution Optical Velocity Fields Of 11 Low Surface Brightness Galaxies, Stacy S. Mcgaugh

Faculty Scholarship

We present high-resolution two-dimensional velocity fields from integral field spectroscopy, along with derived rotation curves for 11 low surface brightness galaxies. We fit NFW and pseudoisothermal halo models to the new data combined with previous long-slit and H I data. In most cases, we find the pseudoisothermal halo to better represent the data than the NFW halo, as the NFW concentrations are often lower than expected for a ACDM cosmology. We also compare our results to previous studies and find that including the new two-dimensional optical data does not significantly alter the halo parameters but does decrease the uncertainties by …

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The Shape Of Dark Matter Haloes: Dependence On Mass, Redshift, Radius And Formation, Ricardo Flores, Brandon Allgood, Joel Primack, Andrey Kravtsov, Risa Wechsler, Andreas Faltenbacher, James Bullock Apr 2006

The Shape Of Dark Matter Haloes: Dependence On Mass, Redshift, Radius And Formation, Ricardo Flores, Brandon Allgood, Joel Primack, Andrey Kravtsov, Risa Wechsler, Andreas Faltenbacher, James Bullock

Physics Faculty Works

Using six high-resolution dissipationless simulations with a varying box size in a flat Lambda cold dark matter (ΛCDM) universe, we study the mass and redshift dependence of dark matter halo shapes for Mvir= 9.0 × 1011− 2.0 × 1014h−1 M⊙, over the redshift range z= 0–3, and for two values of σ8= 0.75 and 0.9. Remarkably, we find that the redshift, mass and σ8 dependence of the mean smallest-to-largest axis ratio of haloes is well described by the simple power-law relation 〈s〉= (0.54 ± 0.02)(Mvir/M*)−0.050±0.003, where s is measured at 0.3Rvir, and the z and σ8 dependences are governed by …

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Multiwavelength Observations Of The Blazar Markarian 421 In 2002 December And 2003 January, P. T. Reynolds, Veritas Apr 2006

Multiwavelength Observations Of The Blazar Markarian 421 In 2002 December And 2003 January, P. T. Reynolds, Veritas

Physical Sciences Publications

We report on a multiwavelength campaign on the TeV γ-ray blazar Mrk 421 performed during 2002 December and 2003 January. These target of opportunity observations were initiated by the detection of X-ray and TeV γ-ray flares with the All Sky Monitor (ASM) on board the Rossi X-Ray Timing Explorer (RXTE) and the 10 m Whipple γ-ray telescope. The campaign included observational coverage in the radio (University of Michigan Radio Astronomy Observatory), optical (Boltwood, La Palma KVA 0.6 m; WIYN 0.9 m), X-ray (RXTE pointed telescopes), and TeV γ-ray (Whipple and HEGRA) bands. At TeV energies, the observations revealed several flares …

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Theoretical Uncertainties In Red Giant Branch Evolution: The Red Giant Branch Bump, Stephan R. R. Bjork, Brian Chaboyer Apr 2006

Theoretical Uncertainties In Red Giant Branch Evolution: The Red Giant Branch Bump, Stephan R. R. Bjork, Brian Chaboyer

Dartmouth Scholarship

A Monte Carlo simulation exploring uncertainties in standard stellar evolution theory on the red giant branch of metal-poor globular clusters has been conducted. Confidence limits are derived on the absolute V-band magnitude of the bump in the red giant branch luminosity function (MV,b) and the excess number of stars in the bump, Rb. The analysis takes into account uncertainties in the primordial helium abundance, abundance of α-capture elements, radiative and conductive opacities, nuclear reaction rates, neutrino energy losses, the treatments of diffusion and convection, the surface boundary conditions, and color transformations. The uncertainty in …

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From Canonical To Enhanced Extra Mixing In Low‐Mass Red Giants: Tidally Locked Binaries, Pavel A. Denissenkov, Brian Chaboyer, Ke Li Apr 2006

From Canonical To Enhanced Extra Mixing In Low‐Mass Red Giants: Tidally Locked Binaries, Pavel A. Denissenkov, Brian Chaboyer, Ke Li

Dartmouth Scholarship

Stellar models that incorporate simple diffusion or shear-induced mixing are used to describe canonical extra mixing in low-mass red giants of low and solar metallicity. These models are able to simultaneously explain the observed Li and CN abundance changes along the upper red giant branch (RGB) in field low-metallicity stars and match photometry, rotation, and 12C/13C ratios for stars in the old open cluster M67. The shear mixing model requires that main-sequence (MS) progenitors of upper RGB stars possessed rapidly rotating radiative cores and that specific angular momentum was conserved in each of their mass shells during …

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Compositional Stability Of Fept Nanoparticles On Sio2/Si During Annealing, Richard R. Vanfleet, B. Yao, R. V. Petrova, K. R. Coffey Apr 2006

Compositional Stability Of Fept Nanoparticles On Sio2/Si During Annealing, Richard R. Vanfleet, B. Yao, R. V. Petrova, K. R. Coffey

Faculty Publications

The loss of Fe due to oxidation or diffusion into the substrate can prevent the successful preparation of well-ordered, stoichiometric, FePt nanoparticles. In this work we report the composition changes during annealing observed for small (<10 nm) FePt nanoparticles on thermally grown SiO2 layers on Si wafer substrates. Additionally, we describe the use of a controlled reducing gas mixture, Ar+H2+H2O, to reduce the loss of Fe.

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Infrared Spectroscopy Of Symbiotic Stars. Iv. V2116 Ophiuchi/Gx 1+4, The Neutron Star Symbiotic, Kenneth H. Hinkle, Francis C. Fekel, Richard R. Joyce, Peter R. Wood, Verne V. Smith, Thomas Lebzelter Apr 2006

Infrared Spectroscopy Of Symbiotic Stars. Iv. V2116 Ophiuchi/Gx 1+4, The Neutron Star Symbiotic, Kenneth H. Hinkle, Francis C. Fekel, Richard R. Joyce, Peter R. Wood, Verne V. Smith, Thomas Lebzelter

Information Systems and Engineering Management Research Publications

We have computed, using 17 infrared radial velocities, the first set of orbital elements for the M giant in the symbiotic binary V2116 Ophiuchi. The giant's companion is a neutron star, the bright X-ray source GX 1+4. We rule out the previously proposed period of 304 days and instead find an orbital period of 1161 days, by far the longest of any known X-ray binary. The orbit has a modest eccentricity of 0.10, with an orbital circularization time of ≲5 × 106 yr. The large mass function of the orbit significantly restricts the mass of the M giant. Adopting a …

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Post-Outburst Infrared Spectra Of V1647 Ori, The Illuminating Star Of Mcneil's Nebula, Erika Gibb, T Rettig, S Brittain, D Wasikowski, Theodore Simon, William Vacca, Michael Cushing Apr 2006

Post-Outburst Infrared Spectra Of V1647 Ori, The Illuminating Star Of Mcneil's Nebula, Erika Gibb, T Rettig, S Brittain, D Wasikowski, Theodore Simon, William Vacca, Michael Cushing

Physics Faculty Works

V1647 Ori is a low-mass star in the L1630 star-forming region that underwent an outburst in late 2003 and early 2004. We present postoutburst infrared spectra obtained with NIRSPEC (Keck II) and SpeX (IRTF) and compare these to spectra taken during the outburst. The results show that the temperature of the hot CO formed in the inner part of the disk has declined by ~800 K, while the water and CO ice and low-J CO gas features remained unchanged, consistent with previous assertions that the latter, low-temperature features arise in the foreground cloud. The P Cygni profiles of the Paschen …

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Absolute Magnitude Distributions And Light Curves Of Stripped-Envelope Supernovae, D. Richardson, D. Branch, E. Baron Apr 2006

Absolute Magnitude Distributions And Light Curves Of Stripped-Envelope Supernovae, D. Richardson, D. Branch, E. Baron

Faculty and Staff Publications

The absolute visual magnitudes of three Type IIb, 11 Type Ib, and 13 Type le supernovae (collectively known as stripped-envelope supernovae) are studied by collecting data on the apparent magnitude, distance, and interstellar extinction of each event. Weighted and unweighted mean absolute magnitudes of the combined sample, as well as various subsets of the sample, are reported. The limited sample size and the considerable uncertainties, especially those associated with extinction in the host galaxies, prevent firm conclusions regarding differences between the absolute magnitudes of supernovae of Types Ib and Ic, and regarding the existence of separate groups of over-luminous and …

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An Astronomical Account: A History Of Hatter Planetarium From 1966-2006, Jonathan D. Neu Apr 2006

An Astronomical Account: A History Of Hatter Planetarium From 1966-2006, Jonathan D. Neu

Hidden in Plain Sight Projects

When most individuals stare up at the vast dome of Hatter Planetarium, they often gaze upon the projected stars appearing on its surface, listening to an astronomical story told by one of its operators. However, there is a second story told by the planetarium itself. This story is the history of Hatter Planetarium, which spans five decades and includes the events in the lives of several individuals who have played a critical role in its existence at Gettysburg College. Its history has encompassed several phases of Gettysburg College traditions but is in danger of passing permanently and fixedly into the …

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Stargazing: Observatories At Gettysburg College, 1874-Present, Andrew A. Carlson Apr 2006

Stargazing: Observatories At Gettysburg College, 1874-Present, Andrew A. Carlson

Hidden in Plain Sight Projects

Astronomy has long been a subject which has attracted the interest of man. Examples of early astronomers can be found in many ancient civilizations, including but not limited to, the Egyptians, the Chinese and the Greeks. As time passed the methods for interpreting the stars and theories that surrounded them changed concordant with the technology available. One of the largest breakthroughs in the world of astronomy was the invention of the telescope in the early seventeenth century. Often mis-attributed to Galileo (who was responsible for building the first reflecting telescope in 1688), the telescope was actually first designed by a …

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Post-Outburst Infrared Spectra Of V1647 Ori, The Illuminating Star Of Mcneil's Nebula, E L. Gibb, T W. Rettig, Sean D. Brittain, D Wasikowski, Theodore Simon, William D. Vacca, Michael C. Cushing, C Kulesa Apr 2006

Post-Outburst Infrared Spectra Of V1647 Ori, The Illuminating Star Of Mcneil's Nebula, E L. Gibb, T W. Rettig, Sean D. Brittain, D Wasikowski, Theodore Simon, William D. Vacca, Michael C. Cushing, C Kulesa

Publications

V1647 Ori is a low mass star in the L1630 star-forming region that underwent an outburst in late 2003/early 2004. We present post-outburst infrared spectra obtained with NIRSPEC (Keck II) and SpeX (IRTF) and compare these to spectra taken during the outburst. The results show that the temperature of the hot CO formed in the inner part of the disk has declined by ~800 K, while the water and CO ice and low-J CO gas features remained unchanged, consistent with previous assertions that the latter, low-temperature features arise in the foreground cloud. The P-Cygni profiles of the Paschen series that …

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The Eclipsing Binary V1061 Cygni: Confronting Stellar Evolution Models For Active And Inactive Solar-Type Stars, Guillermo Torres, Claud H. Sandberg Lacy, Laurence A. Marschall, Holly A. Sheets, Jeff A. Mader Apr 2006

The Eclipsing Binary V1061 Cygni: Confronting Stellar Evolution Models For Active And Inactive Solar-Type Stars, Guillermo Torres, Claud H. Sandberg Lacy, Laurence A. Marschall, Holly A. Sheets, Jeff A. Mader

Physics and Astronomy Faculty Publications

We present spectroscopic and photometric observations of the chromospherically active (X-ray strong) eclipsing binary V1061 Cyg (P = 2.35 days) showing that it is in reality a hierarchical triple system. We combine these observations with Hipparcos intermediate data (abscissa residuals) to derive the outer orbit with a period of 15.8 yr. We determine accurate values for the masses, radii, and effective temperatures of the eclipsing binary components, as well as for the mass and temperature of the third star. For the primary we obtain M = 1.282 ± 0.015 M⊙, R = 1.615 ± 0.017 R⊙, Teff = 6180 ± …

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Spatially Resolved Mid-Infrared Spectroscopy Of Ngc 1068: The Nature And Distribution Of The Nuclear Material, R. E. Mason, T. R. Geballe, C. Packham, N. A. Levenson, Moshe Elitzur, R. S. Fisher, E. Perlman Apr 2006

Spatially Resolved Mid-Infrared Spectroscopy Of Ngc 1068: The Nature And Distribution Of The Nuclear Material, R. E. Mason, T. R. Geballe, C. Packham, N. A. Levenson, Moshe Elitzur, R. S. Fisher, E. Perlman

Physics and Astronomy Faculty Publications

We present spatially resolved, near-diffraction-limited 10 μm spectra of the nucleus of the Seyfert 2 galaxy NGC 1068, obtained with Michelle, the mid-IR imager and spectrometer on the 8.1 m Gemini North Telescope. The spectra cover the nucleus and the central 6.0” × 0.4” of the ionization cones at a spatial resolution of approximately 0.4” (≈30 pc). The spectra extracted in 0.4” steps along the slit reveal striking variations in continuum slope, silicate feature profile and depth, and fine-structure line fluxes on subarcsecond scales, illustrating in unprecedented detail the complexity of the circumnuclear regions of NGC 1068 at mid-IR …

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The Eclipsing Binary V1061 Cygni: Confronting Stellar Evolution Models For Active And Inactive Solar-Type Stars, Guillermo Torres, Claud H. Lacy, L. A. Marshall, Holly A. Sheets, Jeff A. Mader Apr 2006

The Eclipsing Binary V1061 Cygni: Confronting Stellar Evolution Models For Active And Inactive Solar-Type Stars, Guillermo Torres, Claud H. Lacy, L. A. Marshall, Holly A. Sheets, Jeff A. Mader

Dartmouth Scholarship

We present spectroscopic and photometric observations of the eclipsing system V1061 Cyg (P = 2.35 days). A third star is visible in the spectrum, and the system is a hierarchical triple. We combine the radial velocities for the three stars, times of eclipse, and intermediate astrometric data from the Hipparcos mission (abscissa residuals) to establish the elements of the outer orbit, which is eccentric and has a period of 15.8 yr. We determine accurate values for the masses, radii, and effective temperatures of the binary components: MAa = 1.282 ± 0.015 M☉, RAa = 1.615 …

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The Viscous Catenary, John Koulakis Apr 2006

The Viscous Catenary, John Koulakis

Pomona Senior Theses

Variational techniques are used to develop a theory for the time evolution of a thin strand of viscous fluid suspended from two points. The shape of the strand is approximated to be a parabola and energy conservation is used to derive a differential equation modeling the change in height over time. Data is collected with a high resolution camera and a strobe light to obtain the position and shape of the strand over multiple intervals of time. Three very different and unexpected types of behaviors are observed depending on the initial thickness and shape of the filament. The approximation fits …

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Investigation Of Carbon Nanotube Growth Using A Nozzle Cvd Method, James Mcfarland Apr 2006

Investigation Of Carbon Nanotube Growth Using A Nozzle Cvd Method, James Mcfarland

Pomona Senior Theses

This work uses a modification of the chemical vapor deposition (CVD) technique to study the effects of source gas flow geometry (and the corresponding parameters) on carbon nanotube growth. Our approach is to flow the carbon-containing source gas through a nozzle, projecting the gas stream onto targeted regions of the substrate. This technique not only allows the potential for localized nanotube growth, but also offers an interesting opportunity to provide an experimental test of theoretical nanotube growth models.

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Tomographic Approach To Resolving The Distribution Of Lisa Galactic Binaries, Soumya Mohanty, Rajesh K. Nayak Apr 2006

Tomographic Approach To Resolving The Distribution Of Lisa Galactic Binaries, Soumya Mohanty, Rajesh K. Nayak

Physics & Astronomy Faculty Publications

The space based gravitational wave detector LISA (Laser Interferometer Space Antenna) is expected to observe a large population of Galactic white dwarf binaries whose collective signal is likely to dominate instrumental noise at observational frequencies in the range 10−4 to 10−3  Hz. The motion of LISA modulates the signal of each binary in both frequency and amplitude—the exact modulation depending on the source direction and frequency. Starting with the observed response of one LISA interferometer and assuming only Doppler modulation due to the orbital motion of LISA, we show how the distribution of the entire binary population in frequency and …

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The Structure Of Flux Transfer Events Recovered From Cluster Data, H Hasegawa, B U. Ö Sonnerup, C J. Owen, B Klecker, G Paschmann, A Balogh, H Re`Me Mar 2006

The Structure Of Flux Transfer Events Recovered From Cluster Data, H Hasegawa, B U. Ö Sonnerup, C J. Owen, B Klecker, G Paschmann, A Balogh, H Re`Me

Dartmouth Scholarship

The structure and formation mechanism of a to- tal of five Flux Transfer Events (FTEs), encountered on the equatorward side of the northern cusp by the Cluster space- craft, with separation of ∼5000 km, are studied by apply- ing the Grad-Shafranov (GS) reconstruction technique to the events. The technique generates a magnetic field/plasma map of the FTE cross section, using combined magnetic field and plasma data from all four spacecraft, under the assump- tion that the structure is two-dimensional (2-D) and time- independent. The reconstructed FTEs consist of one or more magnetic flux ropes embedded in the magnetopause, suggest- ing …

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The Violation Of Bell's Inequality In A Deterministic But Nonlocal Model, Stephanie Allred Magleby Mar 2006

The Violation Of Bell's Inequality In A Deterministic But Nonlocal Model, Stephanie Allred Magleby

Theses and Dissertations

This thesis investigates the violation of Bell's Inequality through the use of nonlocal measurement schemes as encapsulated in a quasi-deterministic toy model. This toy model, called the Q Box, is reminiscent of Mermin's Box in that it describes a system that appears to be deterministic yet produces the statistics of a quantum type system. [1] The workings of the Q Box are detailed both as a thought experiment and as a computer simulation. Nonlocal measurement protocols similar to those which generate a violation of Bell's Inequality in the Q Box are also applied to Mermin's Box, with comparable results. [1] …

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Rotational And Cyclical Variability In Γ Cassiopeia, Myron A. Smith, Gregory W. Henry, Ethan Vishniac Mar 2006

Rotational And Cyclical Variability In Γ Cassiopeia, Myron A. Smith, Gregory W. Henry, Ethan Vishniac

Information Systems and Engineering Management Research Publications

γ Cas is an unusual classical Be star for which the optical-band and hard X-ray fluxes vary on a variety of timescales. We report results of a 9 yr monitoring effort on this star with a robotic ground-based (APT) telescope in the B, V filter system, as well as simultaneous observations in 2004 November with this instrument and the RXTE. Our observations disclosed no correlated optical response to the rapid X-ray flares in this star, nor did the star show any sustained flux changes any time during two monitored nights in either wavelength regime. Consistent with an earlier study by …

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Physical Conditions In The Interstellar Medium Toward Hd 185418, Gargi Shaw, Gary J. Ferland, R. Srianand, N. P. Abel Mar 2006

Physical Conditions In The Interstellar Medium Toward Hd 185418, Gargi Shaw, Gary J. Ferland, R. Srianand, N. P. Abel

Physics and Astronomy Faculty Publications

We have developed a complete model of the hydrogen molecule as part of the spectral simulation code Cloudy. Our goal is to apply this to spectra of high-redshift star-forming regions where H2 absorption is seen, but where few other details are known, to understand its implication for star formation. The microphysics of H2 is intricate, and it is important to validate these numerical simulations in better understood environments. This paper studies a well-defined line of sight through the Galactic interstellar medium (ISM) as a test of the microphysics and methods we use. We present a self-consistent calculation of …

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Prediction Of Flight-Level Radiation Hazards Due To Solar Energetic Protons, Matthew P. Sattler Mar 2006

Prediction Of Flight-Level Radiation Hazards Due To Solar Energetic Protons, Matthew P. Sattler

Theses and Dissertations

The radiation environment at aircraft altitudes is caused primarily by high-energy particles originating from outside the near-earth environment. These particles generally come from outside our solar system and are called galactic cosmic rays. Occasionally however, a transient solar event will also accelerate energetic protons toward the earth. If these protons reach the upper atmosphere, they produce secondary particles via collisions, resulting in increased radiation levels in the atmosphere. Air crews and electronic systems flying at high altitudes during one of these events are subjected to these increased levels of radiation which can result in health problems for personnel and soft …

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Spectroscopy And Photometry Of The Double-Lined Binary Hd 149420, Francis C. Fekel, Gregory W. Henry Mar 2006

Spectroscopy And Photometry Of The Double-Lined Binary Hd 149420, Francis C. Fekel, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We have used new spectroscopic and photometric observations of HD 149420 to obtain an improved orbital element solution and determine some basic properties of the system. This double-lined binary has an orbital period of 3.39430 days, a circular orbit, and a mass ratio of 0.52. The primary is somewhat evolved, with an A9 IV spectral type, while the secondary is estimated to be an F5: dwarf. The secondary may be synchronously rotating, but the primary is rotating substantially slower than its synchronous velocity. Our photometric observations confirm the light variability and period found by Hipparcos. We determine a photometric period …

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Accurate Evolutions Of Orbiting Black-Hole Binaries Without Excision, M. Campanelli, C. O. Lousto, P. Marronetti, Z. Zlochower Mar 2006

Accurate Evolutions Of Orbiting Black-Hole Binaries Without Excision, M. Campanelli, C. O. Lousto, P. Marronetti, Z. Zlochower

Physics & Astronomy Faculty Publications

We present a new algorithm for evolving orbiting black-hole binaries that does not require excision or a corotating shift. Our algorithm is based on a novel technique to handle the singular puncture conformal factor. This system, based on the Baumgarte-Shapiro-Shibata-Nakamura formulation of Einstein’s equations, when used with a ‘‘precollapsed’’ initial lapse, is nonsingular at the start of the evolution and remains nonsingular and stable provided that a good choice is made for the gauge. As a test case, we use this technique to fully evolve orbiting black-hole binaries from near the innermost stable circular orbit regime. We show fourth-order convergence …

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B And I-Band Optical Micro-Variability Observations Of The Bl Lac Objects S5 2007+777 And 3c 371, Niall Smith, Et. Al. Feb 2006

B And I-Band Optical Micro-Variability Observations Of The Bl Lac Objects S5 2007+777 And 3c 371, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

We have observed S5 2007+777 and 3C 371 in the B and I bands for 13 and 8 nights, respectively, during various observing runs in 2001, 2002 and 2004. The observations resulted in almost evenly sampled light curves, h long. We do not detect any flares within the observed light curves, but we do observe small amplitude, significant variations, in both bands, on time scales of hours and days. The average variability amplitude on time scales of minutes/hours is ~2.5% and ~% in the case of S5 2007+777 and 3C 371, respectively. The average amplitudes increase to % and %, …

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