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Astrophysics papers — page 102

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Spectra and anisotropy of magnetic fluctuations in the Earth's magnetosheath: Cluster observations
We investigate the spectral shape, the anisotropy of the wave vector distributions and the anisotropy of the amplitudes of the magnetic fluctuations in the Earth's magnetosheath within a broad…
Olga Alexandrova, Catherine Lacombe, Andre MangeneyOct 3, 2008
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Section on Supernova remnants and cosmic rays of the White Paper on the Status and Future of Ground-based Gamma-ray Astronomy
This is a report on the findings of the SNR/cosmic-ray working group for the white paper on the status and future of ground-based gamma-ray astronomy. The white paper is an APS commissioned document,…
M. Pohl, A. Abdo, A. Atoyan et al.Oct 3, 2008
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Modeling Massive Stars with Rotation: the Case of Nitrogen Enrichments
Recently, the concept of rotational mixing has been challenged by some authors (e.g. Hunter et al. 2008). We show that the excess N/H is a multivariate function f(M, age, v, sin i, multiplicity,Z).…
A. Maeder, G. Meynet, S. Ekstrom et al.Oct 3, 2008
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Evolution and chemical and dynamical effects of high-mass stars
We review general characteristics of massive stars, present the main observable constraints that stellar models should reproduce. We discuss the impact of massive star nucleosynthesis on the early…
Georges Meynet, Cristina Chiappini, Cyril Georgy et al.Oct 3, 2008
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INTEGRAL Cross-calibration Status: Crab observations between 3 keV and 1 MeV
We present results of Crab observations by the INTEGRAL instruments. A simultaneous fit allows us to demonstrate that INTEGRAL provides reliable spectra over its wide energy range.
E. Jourdain, D. Gotz, N. J. Westergaard et al.Oct 3, 2008
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SN 2006gy: was it really extra-ordinary?
We present an optical photometric and spectroscopic study of the very luminous type IIn SN 2006gy for a time period spanning more than one year. In photometry, a broad, bright (MR~-21.7) peak…
I. Agnoletto, S. Benetti, E. Cappellaro et al.Oct 3, 2008
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Numerical Analysis of Relativistic Boltzmann-kinetic Equations to Solve Relativistic Shock Layer Problems
The relativistic shock layer problem was numerically analyzed by using two relativistic Boltzmann-kinetic equations. One is Marle model, and the other is Anderson-Witting model. As with Marle model,…
Ryosuke Yano, Kojiro Suzuki, Hisayasu KurodaOct 3, 2008
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Sites for Gamma-ray Astronomy in Argentina
We have searched for possible sites in Argentina for the installation of large air Cherenkov telescope arrays and water Cherenkov systems. At present seven candidates are identified at altitudes from…
A. C. Rovero, G. E. Romero, I. Allekotte et al.Oct 3, 2008
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Flux-Vector-Splitting (FVS) method for Z4 formalism and its numerical analysis
The previously developed Flux-Vector-Splitting (FVS) method was formulated here for the first-order version of Z4 formalism. Then, the characteristics of this method formulated for Z4 formalism were…
Ryosuke Yano, Kojiro Suzuki, Hisayasu KurodaOct 3, 2008
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Modeling Merging Galaxies using MINGA - Improving Restricted N-body by Dynamical Friction
Modeling interacting galaxies to reproduce observed systems is still a challenge due to the extended parameter space (among other problems). Orbit and basic galaxy parameters can be tackled by fast…
Hanns P. Petsch, Christian TheisOct 3, 2008
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What do dynamical cluster masses really tell us about dynamics?
The diagnostic age versus mass-to-light ratio diagram is often used in attempts to constrain the shape of the stellar initial mass function, and the stability and the potential longevity of…
Richard de Grijs, M. B. N. Kouwenhoven, Simon P. GoodwinOct 3, 2008
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On-Line Long-Exposure Phase Diversity: a Powerful Tool for Sensing Quasi-Static Aberrations of Extreme Adaptive Optics Imaging Systems
The phase diversity technique is a useful tool to measure and pre-compensate for quasi-static aberrations, in particular non-common path aberrations, in an adaptive optics corrected imaging system.…
L. M. Mugnier, J. -F. Sauvage, T. Fusco et al.Oct 3, 2008
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Chemical Abundances of the Leo II Dwarf Galaxy
We use previously-published moderate-resolution spectra in combination with stellar atmosphere models to derive the first measured chemical abundance ratios in the Leo II dSph galaxy. We find that…
Matthew Shetrone, Michael H. Siegel, David O. Cook et al.Oct 3, 2008
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Clouds, Brightening and Multiplicity Across the L Dwarf/T Dwarf Transition
The transition between the two lowest-luminosity spectral classes of brown dwarfs--the L dwarfs and T dwarfs--is traversed by nearly all brown dwarfs as they cool over time. Yet distinct features of…
Adam J. BurgasserOct 3, 2008
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Ultracool Subdwarfs: The Halo Population Down to the Substellar Limit
Ultracool subdwarfs are low luminosity, late-type M and L dwarfs that exhibit spectroscopic indications of subsolar metallicity and halo kinematics. Their recent discovery and ongoing investigation…
Adam J. Burgasser, Sebastien Lepine, Nicolas Lodieu et al.Oct 3, 2008
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Dynamical Opacity-Sampling Models of Mira Variables. I: Modelling Description and Analysis of Approximations
We describe the Cool Opacity-sampling Dynamic EXtended (CODEX) atmosphere models of Mira variable stars, and examine in detail the physical and numerical approximations that go in to the model…
M. J. Ireland, M. Scholz, P. R. WoodOct 3, 2008
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Modification to the Luminosity Distance Redshift Relation in Modified Gravity Theories
We derive an expression for the luminosity distance as a function of redshift for a flat Robertson-Walker spacetime perturbed by arbitrary scalar perturbations possibly produced by a modified gravity…
Éanna É. Flanagan, Eran Rosenthal, Ira M. WassermanOct 2, 2008
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Galaxy Clusters at 0.9<z<1.7 in the AKARI NEP deep field
There is a huge gap between properties of red-sequence selected massive galaxy clusters at z<1 and Lyman-break selected proto-clusters at z>3. It is important to understand when and how the z>3…
Tomotsugu Goto, Hitoshi Hanami, Myungshin Im et al.Oct 2, 2008
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Observation of Galactic Gamma-ray Sources with VERITAS
We report on VERITAS observations at energies above 200 GeV of known or potential galactic gamma-ray sources. The observed objects comprise pulsars, pulsar wind nebulae, high-mass X-ray binaries and…
G. MaierOct 2, 2008
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On the nature of HD 207331: a new Delta Scuti variable
While testing a Stromgren spectrophotometer attached to the 1.5-m telescope at the San Pedro Martir observatory, Mexico, a number of A-type stars were observed, one of which, HD 207331, presented…
L. Fox Machado, W. J. Schuster, C. Zurita et al.Oct 2, 2008
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VERITAS Observations of the Arrival Directions of the Highest Energy Cosmic Rays
The recent discovery by the Pierre Auger collaboration of anisotropy in the arrival directions of the highest energy cosmic rays, correlated with the positions of nearby active galactic nuclei,…
J. HolderOct 2, 2008
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Cosmological CPT violating effect on CMB polarization
A dark energy scalar (or a function of the Ricci scalar) coupled with the derivative to the matter fields will violate the CPT symmetry during the expansion of the Universe. This type of…
Mingzhe Li, Xinmin ZhangOct 2, 2008
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Time Averaged VHE Spectrum of Mrk 421 in 2005
The blazar Mrk421 was observed independently, but contemporaneously, in 2005 at TeV energies by MAGIC, the Whipple 10m telescope, and by a single VERITAS telescope during the construction phase of…
M. K. DanielOct 2, 2008
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Phase Closure Image Reconstruction for Future VLTI Instrumentation
Classically, optical and near-infrared interferometry have relied on closure phase techniques to produce images. Such techniques allow us to achieve modest dynamic ranges. In order to test the…
Mercedes E. Filho, Stephanie Renard, Paulo Garcia et al.Oct 2, 2008
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Phase Referencing in Optical Interferometry
One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and…
Mercedes E. Filho, Paulo Garcia, Gilles Duvert et al.Oct 2, 2008
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