Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Astrophysics and Astronomy

2002

Institution
Keyword
Publication
Publication Type
File Type

Articles 121 - 132 of 132

Full-Text Articles in Physical Sciences and Mathematics

Chandra Observation Of Supernova Remnant G54.1+0.3: A Close Cousin Of The Crab Nebula, Fj Lu, Qd Wang, B Aschenbach, P Durouchoux, Lm Song Jan 2002

Chandra Observation Of Supernova Remnant G54.1+0.3: A Close Cousin Of The Crab Nebula, Fj Lu, Qd Wang, B Aschenbach, P Durouchoux, Lm Song

Astronomy Department Faculty Publication Series

We present a Chandra Advanced CCD Imaging Spectrometer observation of supernova remnant G54.1+0.3. This supernova remnant is resolved into several distinct X-ray-emitting components: a central bright pointlike source (CXOU J193030.13+185214.1), a surrounding ring, bipolar elongations, plus low surface brightness diffuse emission. The spectra of these components are all well described by power-law models; the spectral index steepens with increasing distance from the pointlike source. We find no evidence for any thermal plasma emission that would correspond to shocked interstellar medium or ejecta. The observed morphological and spectral characteristics suggest that G54.1+0.3 is the closest "cousin" of the Crab Nebula—a pulsar …

Go to article

Hiccups In The Night: X-Ray Monitoring Of The Two Crab-Like Lmc Pulsars, Ev Gotthelf, W Zhang, Fe Marshall, J Middleditch, Qd Wang Jan 2002

Hiccups In The Night: X-Ray Monitoring Of The Two Crab-Like Lmc Pulsars, Ev Gotthelf, W Zhang, Fe Marshall, J Middleditch, Qd Wang

Astronomy Department Faculty Publication Series

We are undertaking an extensive X-ray monitoring campaign of the two Crab-like pulsars in the Large Magellanic Clouds, PSR B0540-69 and PSR J0537-6910. We present our current phase-connected timing analysis derived from a set of 50 pointed X-ray observations spanning several years. From our initial 1.2 yr monitoring program of the young 50 ms pulsar PSR B0540-69, we find the first compelling evidence for a glitch in its rotation. This glitch is characterized by Delta nu / nu = (1.90+-0.05) x 10-9 and Delta nudot / nudot = (8.5+-0.5) x 10-5. Taking into account the …

Go to article

Bouncing Branes, Emil Prodanov Jan 2002

Bouncing Branes, Emil Prodanov

Articles

Two classical scalar fields are minimally coupled to gravity in the Kachru-Shulz-Silverstein scenario with a rolling fifth radius. A Tolman wormhole solution is found for a R x S^3 brane with Lorentz metric and for a R x AdS_3 brane with positive definite metric.

Go to article

Group-Fitted Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors, N. Dimakis, Grant Bunker Jan 2002

Group-Fitted Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors, N. Dimakis, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

X-ray absorption fine structure (XAFS) spectroscopy is one of the few direct probes of the structure of metalloprotein binding that is equally applicable to proteins in crystals, solutions, and membranes. Despite considerable progress in the calculation of the photoelectron scattering aspects of XAFS, calculation of the vibrational aspects has lagged because of the difficulty of the calculations. We report here initial results that express single- and multiple-scattering Debye-Waller factors as polynomial functions of first shell radial distance for metal-peptide complexes, enabling quantitatively accurate full multiple-scattering XAFS data analysis of active sites of unknown structure at arbitrary temperatures without the use …

Go to article

Correlation Functions Near Modulated And Rough Surfaces, Andreas Hanke, Mehran Kardar Jan 2002

Correlation Functions Near Modulated And Rough Surfaces, Andreas Hanke, Mehran Kardar

Physics and Astronomy Faculty Publications and Presentations

In a system with long-ranged correlations, the behavior of correlation functions is sensitive to the presence of a boundary. We show that surface deformations strongly modify this behavior as compared to a flat surface. The modified near surface correlations can be measured by scattering probes. To determine these correlations, we develop a perturbative calculation in the deformations in height from a flat surface. Detailed results are given for a regularly patterned surface, as well as for a self-affinely rough surface with roughness exponent ζ. By combining this perturbative calculation in height deformations with the field-theoretic renormalization-group approach, we also estimate …

Go to article

Tightness Of Slip-Linked Polymer Chains, Ralf Metzler, Andreas Hanke, Paul G. Dommersnes, Yacov Kantor, Mehran Kardar Jan 2002

Tightness Of Slip-Linked Polymer Chains, Ralf Metzler, Andreas Hanke, Paul G. Dommersnes, Yacov Kantor, Mehran Kardar

Physics and Astronomy Faculty Publications and Presentations

We study the interplay between entropy and topological constraints for a polymer chain in which sliding rings (slip links) enforce pair contacts between monomers. These slip links divide a closed ring polymer into a number of subloops which can exchange length among each other. In the ideal chain limit, we find the joint probability density function for the sizes of segments within such a slip-linked polymer chain (paraknot). A particular segment is tight (small in size) or loose (of the order of the overall size of the paraknot) depending on both the number of slip links it incorporates and its …

Go to article

Wiyn Open Cluster Study Xi: Wiyn1 3.5m Deep Photometry Of M35 (Ngc 2168), Ted Von Hippel, Aaron Steinhauer, Ata Sarajedini, Constantine P. Deliyannis Jan 2002

Wiyn Open Cluster Study Xi: Wiyn1 3.5m Deep Photometry Of M35 (Ngc 2168), Ted Von Hippel, Aaron Steinhauer, Ata Sarajedini, Constantine P. Deliyannis

Publications

We present deep BV I observations of the core of M35 and a nearby comparison field obtained at the WIYN 3.5m telescope under excellent seeing conditions. These observations probe to V > 26, and display the lower main sequence in BV and V I CMDs down to V = 23.3 and 24.6, respectively. At these faint magnitudes the background Galactic field stars are far more numerous than the cluster stars, yet by using a smoothing technique and CMD density distribution subtraction we are able to recover the cluster fiducial main sequence and luminosity function to V = 24.6. We find the …

Go to article

The Planetary Nebula Spectrograph: The Green Light For Galaxy Kinematics, N. G. Douglas, M. Arnaboldi, K. C. Freeman, K. Kuijken, M. R. Merrifield, Aaron J. Romanowsky, K. Taylor, M. Capaccioli, T. Axelrod, R. Gilmozzi, J. Hart, G. Bloxham, D. Jones Jan 2002

The Planetary Nebula Spectrograph: The Green Light For Galaxy Kinematics, N. G. Douglas, M. Arnaboldi, K. C. Freeman, K. Kuijken, M. R. Merrifield, Aaron J. Romanowsky, K. Taylor, M. Capaccioli, T. Axelrod, R. Gilmozzi, J. Hart, G. Bloxham, D. Jones

Aaron J. Romanowsky

Planetary nebulae (PNe) are now well established as probes of galaxy dynamics and as standard candles in distance determinations. Motivated by the need to improve the efficiency of planetary nebulae searches and the speed with which their radial velocities are determined, a dedicated instrument—the Planetary Nebula Spectrograph, or PN.S—has been designed and commissioned at the 4.2 m William Herschel Telescope. The high optical efficiency of the spectrograph results in the detection of typically ∼150 PNe in galaxies at the distance of the Virgo Cluster in one night of observations. In the same observation, the radial velocities are obtained with an …

Go to article

Comment On ‘‘Stress-Density Ratio Slip-Corrected Reynolds Equation For Ultra-Thin Film Gas Bearing Lubrication’’, Alejandro Garcia Jan 2002

Comment On ‘‘Stress-Density Ratio Slip-Corrected Reynolds Equation For Ultra-Thin Film Gas Bearing Lubrication’’, Alejandro Garcia

Alejandro Garcia

No abstract provided.

Go to article

Comment On ‘‘Stress-Density Ratio Slip-Corrected Reynolds Equation For Ultra-Thin Film Gas Bearing Lubrication’’, Alejandro Garcia Jan 2002

Comment On ‘‘Stress-Density Ratio Slip-Corrected Reynolds Equation For Ultra-Thin Film Gas Bearing Lubrication’’, Alejandro Garcia

Faculty Publications

No abstract provided.

Go to article

Book Review: Flash!: The Hunt For The Biggest Explosions In The Universe, T. D. Oswalt Jan 2002

Book Review: Flash!: The Hunt For The Biggest Explosions In The Universe, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Flash! : the hunt for the biggest explosions in the universe by Govert Schilling. tr. by Naomi Greenberg-Slovin Cambridge, 2002 291p, 0-521-80053-6 $28.00

Go to article

Proceedings Of The First International Conference On Neutrosophy, Neutrosophic Logic, Neutrosophic Set, Neutrosophic Probability And Statistics, Florentin Smarandache Jan 2002

Proceedings Of The First International Conference On Neutrosophy, Neutrosophic Logic, Neutrosophic Set, Neutrosophic Probability And Statistics, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

In 1960s Abraham Robinson has developed the non-standard analysis, a formalization of analysis and a branch of mathematical logic, that rigorously defines the infinitesimals. Informally, an infinitesimal is an infinitely small number. Formally, x is said to be infinitesimal if and only if for all positive integers n one has xxx < 1/n. Let &>0 be a such infinitesimal number. The hyper-real number set is an extension of the real number set, which includes classes of infinite numbers and classes of infinitesimal numbers. Let’s consider the non-standard finite numbers 1+ = 1+&, where “1” is its standard part and “&” its non-standard part, …

Go to article

First Prev