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Astrophysics papers — page 32

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Introducing a Hybrid Method of Radiative Transfer for Smoothed Particle Hydrodynamics
A new means of incorporating radiative transfer into smoothed particle hydrodynamics (SPH) is introduced, which builds on the success of two previous methods - the polytropic cooling approximation as…
Duncan Forgan, Ken Rice, Dimitris Stamatellos et al.Dec 1, 2008
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New high resolution synthetic stellar libraries for the Gaia Mission
High resolution synthetic stellar libraries are of fundamental importance for the preparation of the Gaia Mission. We present new sets of spectral stellar libraries covering two spectral ranges: 300…
R. Sordo, A. Vallenari, J. C. Bouret et al.Dec 1, 2008
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The Gaia Era: synergy between space missions and ground based surveys
The Gaia mission is expected to provide highly accurate astrometric, photometric, and spectroscopic measurements for about 109 objects. Automated classification of detected sources is a key part…
A. Vallenari, R. SordoDec 1, 2008
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On the validity of nonlinear Alfven resonance in space plasmas
In the approximation of linear dissipative magnetohydrodynamics (MHD) it can be shown that driven MHD waves in magnetic plasmas with high Reynolds number exhibit a near resonant behaviour if the…
C. T. M. Clack, I. Ballai, M. S. RudermanDec 1, 2008
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Phase-space structures II: Hierarchical Structure Finder
A new multi-dimensional Hierarchical Structure Finder (HSF) to study the phase-space structure of dark matter in N-body cosmological simulations is presented. The algorithm depends mainly on two…
M. Maciejewski, S. Colombi, V. Springel et al.Dec 1, 2008
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Jets, accretion, coronae and all that: The enigmatic X-rays from the Herbig star HD 163296
Herbig Ae/Be stars (HAeBe) are pre-main sequence objects in the mass range between 2 and 8 solar masses. Their X-ray properties are uncertain and, as yet, unexplained. We want to elucidate the X-ray…
H. M. Guenther, J. H. M. M. SchmittDec 1, 2008
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Radio source stacking and the infrared / radio correlation at microJy flux densities
We investigate the infrared / radio correlation using the technique of source stacking, in order to probe the average properties of radio sources that are too faint to be detected individually. We…
Timothy Garn, Paul AlexanderDec 1, 2008
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High-resolution studies of the twin jet in NGC 1052
The radio loud galaxy NGC 1052 is being studied in an intensive multi-band campaign including X-ray brigthness monitoring and spectroscopic observations, single-dish radio brightness monitoring at…
E. Ros, M. Kadler, Y. Y. Kovalev et al.Dec 1, 2008
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Carbon isotope fractionation in protoplanetary disks
We investigate the gas-phase and grain-surface chemistry in the inner 30 AU of a typical protoplanetary disk using a new model which calculates the gas temperature by solving the gas heating and…
Paul M. Woods, Karen WillacyDec 1, 2008
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VLT/ISAAC Spectra of the Hbeta Region in Intermediate-Redshift Quasars III. Hbeta Broad Line Profile Analysis and Inferences about BLR Structure
[Abridged] We present new VLT ISAAC spectra for 30 quasars, which we combine with previous data to yield a sample of 53 intermediate redshift (z ~ 0.9 - 3.0) sources. The sample is used to explore…
P. Marziani, J. W. Sulentic, G. M. Stirpe et al.Dec 1, 2008
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The Ages, Masses, Evolution and Kinematics of Mira variable
Evidence on the ages and masses of Mira variables is reviewed. Period increases with increasing initial mass. Miras of logP about 3.0 have initial masses of near 4 solar masses. It is suggestd that…
Michael FeastDec 1, 2008
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On the behaviour of stellar winds that exceed the photon-tiring limit
Stars can produce steady-state winds through radiative driving as long as the mechanical luminosity of the wind does not exceed the radiative luminosity at its base. This upper bound on the mass loss…
Allard Jan van Marle, Stanley P. Owocki, Nir J. ShavivDec 1, 2008
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The effects of flux transport on interface dynamos
The operation of an interface dynamo (as has been suggested for the Sun and other stars with convective envelopes) relies crucially upon the effective transport of magnetic flux between two spatially…
J. Mason, D. W. Hughes, S. M. TobiasDec 1, 2008
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Identifying the Potential Biosphere of Mars
Our current knowledge of life on Earth indicates a basic requirement for liquid water. The locations of present liquid water are therefore the logical sites to search for current life on Mars. We…
Eriita G. Jones, Charles H. LineweaverDec 1, 2008
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The WFC3 Galactic Bulge Treasury Program: A First Look at Resolved Stellar Population Tools
[Abridged] When WFC3 is installed on HST, the community will have powerful new tools for investigating resolved stellar populations. The WFC3 Galactic Bulge Treasury program will obtain deep imaging…
Thomas M. Brown, Kailash Sahu, Manuela Zoccali et al.Dec 1, 2008
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Gamma-ray Burst 080319B: Evidence for Relativistic Turbulence, Not Internal Shocks
We show that the excellent optical and gamma-ray data available for GRB 080319B rule out the internal shock model for the prompt emission. The data instead point to a model in which the observed…
Pawan Kumar, Ramesh NarayanDec 1, 2008
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Possible Effects of Pair Echoes on Gamma-Ray Burst Afterglow Emission
High-energy emission from gamma-ray bursts (GRBs) is widely expected but had been sparsely observed until recently when the Fermi satellite was launched. If >TeV gamma rays are produced in GRBs and…
Kohta Murase, Bing Zhang, Keitaro Takahashi et al.Nov 30, 2008
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A generalised Measurement Equation and van Cittert-Zernike theorem for wide-field radio astronomical interferometry
We derive a generalised van Cittert-Zernike (vC-Z) theorem for radio astronomy that is valid for partially polarized sources over an arbitrarily wide field-of-view (FoV). The classical vC-Z theorem…
T. D. Carozzi, G. WoanNov 30, 2008
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Testing Lorentz Invariance with Ultra High Energy Cosmic Ray Spectrum
The GZK cutoff predicted at the Ultra High Energy Cosmic Ray (UHECR) spectrum as been observed by the HiRes and Auger experiments. The results put severe constraints on the effect of Lorentz…
Xiao-Jun Bi, Zhen Cao, Ye Li et al.Nov 30, 2008
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The Cepheid Period-Luminosity Relation (The Leavitt Law) at Mid-Infrared Wavelengths: III. Cepheids in NGC 6822
We present the first application of mid-infrared Period-Luminosity relations to the determination of a Cepheid distance beyond the Magellanic Clouds. Using archival IRAC imaging data on NGC 6822 from…
Barry F. Madore, Jane Rigby, Wendy L. Freedman et al.Nov 30, 2008
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Molecular gas and star formation in the red-sequence counter-rotating disc galaxy NGC 4550
We present observations of the CO(1-0) emission in the central 750 pc (10 arcsec) of the counter-rotating disc galaxy NGC 4550, obtained at the Institut de Radioastronomie Millimetrique (IRAM)…
Alison F. Crocker, Hyunjin Jeong, Shinya Komugi et al.Nov 30, 2008
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The UKIDSS-2MASS Proper Motion Survey I: Ultracool dwarfs from UKIDSS DR4
The UKIRT Infrared Deep Sky Survey (UKIDSS) is the first of a new generation of infrared surveys. Here we combine the data from two UKIDSS components, the Large Area Survey (LAS) and the Galactic…
N. R. Deacon, N. C. Hambly, R. R. King et al.Nov 30, 2008
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Suzaku Results on the Obscured Low-Luminosity Active Galactic Nucleus in NGC 4258
In 2006 June, the obscured low luminosity active galactic nucleus in the nearby Seyfert 1.9 galaxy NGC 4258 was observed with Suzaku for ~ 100 ks. Utilizing the XIS and the HXD, the nucleus emission…
Shin'ya Yamada, Takeshi Itoh, Kazuo Makishima et al.Nov 30, 2008
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Light Curve Morphology Study of UW CrB -- Evidence for a 5 d Superorbital Period
Since its discovery in 1990, UW CrB (also known as MS1603+2600) has remained a peculiar source without firm classification. Our current understanding is that it is an Accretion Disc Corona (ADC) low…
Pasi Hakala, Linnea Hjalmarsdotter, Diana C. Hannikainen et al.Nov 30, 2008
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Sub-Wavelength Resolution Imaging of the Solar Deep Interior
We derive expectations for signatures in the measured travel times of waves that interact with thermal anomalies and jets. A series of numerical experiments that involve the dynamic linear evolution…
Shravan M. Hanasoge, Thomas L. DuvallNov 30, 2008
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