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Astrophysics papers — page 2

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Anisotropic distribution functions for spherical galaxies
A method is presented for finding anisotropic distribution functions for stellar systems with known, spherically symmetric, densities, which depends only on the two classical integrals of the energy…
Zhenglu Jiang, Leonid OssipkovDec 29, 2008
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Quantum vacuum and accelerated expansion
A new approach to extraction of quantum vacuum energy, in the context of the accelerated expansion, is proposed, and it is shown that experimentally realistic orders of values can be derived. The…
Bogusław Broda, Michał SzaneckiDec 29, 2008
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Near-IR spectroscopic ages of massive star clusters in M82
Like other starburst galaxies, M82 hosts compact, massive young star clusters that are interesting both in their own right and as benchmarks for population synthesis models. Can spectral synthesis…
A. Lançon, J. S. Gallagher, M. Mouhcine et al.Dec 29, 2008
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Infall and rotation motions in the HH 111 protostellar system: A flattened envelope in transition to a disk?
We have mapped the central region of the HH 111 protostellar system in 1.33 mm continuum, C18O(J=2-1), 13CO (J=2-1), and SO (NJ=56-45) emission at ~3" resolution with the Submillimeter Array.…
Chin-Fei Lee, Yao-Yuan Mao, Bo ReipurthDec 29, 2008
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Angular Energy Distribution of Collapsar-Jets
Collapsars are fast-spinning, massive stars, whose core collapse liberates an energy, that can be channeled in the form of ultrarelativistic jets. These jets transport the energy from the collapsed…
Akira Mizuta, Miguel A. AloyDec 28, 2008
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Jet breaks and Energetics of Swift GRB X-ray Afterglows
We present a systematic temporal and spectral study of all Swift-XRT observations of GRB afterglows discovered between 2005 January and 2007 December. After constructing and fitting all light curves…
J. L. Racusin, E. W. Liang, D. N. Burrows et al.Dec 28, 2008
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Orbital resonances in discs around braneworld Kerr black holes
Rotating black holes in the brany universe of the Randall-Sundrum type are described by the Kerr geometry with a tidal charge b representing the interaction of the brany black hole and the bulk…
Zdenek Stuchlik, Andrea KotrlovaDec 28, 2008
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Dynamic masses for the close PG1159 binary SDSSJ212531.92-010745.9
SDSSJ212531.92-010745.9 is the first known PG1159 star in a close binary with a late main sequence companion allowing a dynamical mass determination. The system shows flux variations with a…
S Schuh, B Beeck, T NagelDec 28, 2008
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Long-term photometric monitoring of the hybrid subdwarf B pulsator HS0702+6043
Pulsating subdwarf B stars oscillate in short-period p-modes or long-period g-modes. HS 0702 + 6043 is one of currently three objects known to show characteristics of both types and hence is…
R. Lutz, S. Schuh, R. Silvotti et al.Dec 28, 2008
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Spectroscopy of the sdB pulsator HS2201+2610
We present time resolved echelle spectra of the planet-hosting subdwarf B pulsator HS 2201 + 2610 and report on our efforts to extract pulsational radial velocity measurements from this data.
R. Kruspe, S. Schuh, R. Silvotti et al.Dec 28, 2008
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Multi-wavelength photometric variation of PG1605+072
In a large coordinated attempt to further our understanding of the p-mode pulsating sdB star PG1605+072, the Multi-Site Spectroscopic Telescope (MSST) collaboration has obtained simultaneous…
S. Schuh, S. Dreizler, U. Heber et al.Dec 28, 2008
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Dark Stars: the First Stars in the Universe may be powered by Dark Matter Heating
A new line of research on Dark Stars is reviewed, which suggests that the first stars to exist in the universe were powered by dark matter heating rather than by fusion. Weakly Interacting Massive…
Katherine Freese, Peter Bodenheimer, Paolo Gondolo et al.Dec 28, 2008
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PIERNIK mhd code - a multi-fluid, non-ideal extension of the relaxing-TVD scheme (III)
We present a new multi-fluid, grid MHD code PIERNIK, which is based on the Relaxing TVD scheme (Jin & Xin, 1995). The original scheme (see Trac & Pen (2003) and Pen et al. (2003)) has been extended…
Michał Hanasz, Kacper Kowalik, Dominik Wóltański et al.Dec 28, 2008
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The variation of the electromagnetic coupling and quintessence
The properties of quintessence are examined through the study of the variation of the electromagnetic coupling. We consider two simple quintessence models with a modified exponential potential and…
M. C. Bento, R. Gonzalez FelipeDec 28, 2008
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3D Spectroscopic Study of the Line Emitting Regions of Mrk 493
We report the results of 3D spectroscopic observations of Mrk 493 (NLS1 galaxy) with the integral-field spectrograph MPFS of the SAO RAS 6-m telescope. The difference in the slope of the optical…
L. C. Popovic, A. A. Smirnova, J. Kovacevic et al.Dec 28, 2008
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Explosions inside Ejecta and Most Luminous Supernovae
The extremely luminous supernova SN2006gy is explained in the same way as other SNIIn events: light is produced by a radiative shock propagating in a dense circumstellar envelope formed by a previous…
S. I. BlinnikovDec 28, 2008
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Quasi-viscous accretion flow -- I: Equilibrium conditions and asymptotic behaviour
In a novel approach to studying viscous accretion flows, viscosity has been introduced as a perturbative effect, involving a first-order correction in the α-viscosity parameter. This method reduces…
Jayanta K. Bhattacharjee, Atri Bhattacharya, Tapas K. Das et al.Dec 28, 2008
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Observations of the pulsation of the Cepheid l Car with the Sydney University Stellar Interferometer
Observations of the southern Cepheid l Car to yield the mean angular diameter and angular pulsation amplitude have been made with the Sydney University Stellar Interferometer (SUSI) at a wavelength…
J. Davis, A. P. Jacob, J. G. Robertson et al.Dec 28, 2008
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Reversal of the amplitude difference of kHz QPOs in six atoll sources
AIMS: For six neutron-star atoll sources (4U 1608-52, 4U 1636-53, 4U 0614+09, 4U 1728-34, 4U 1820-30 and 4U 1735-44) we investigate the relationship between the observed fractional rms amplitudes of…
Gabriel TorokDec 27, 2008
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The origin of 'Great Walls'
A new semianalytical model that explains the formation and sizes of the 'great walls' - the largest structures observed in the universe is suggested. Although the basis of the model is the…
Sergei ShandarinDec 27, 2008
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Thermal axion constraints in non-standard thermal histories
There is no direct evidence for radiation domination prior to big-bang nucleosynthesis, and so it is useful to consider how constraints to thermally-produced axions change in non-standard thermal…
Daniel Grin, Tristan Smith, Marc KamionkowskiDec 27, 2008
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Constraints on Dark Energy from the Observed Expansion of our Cosmic Horizon
Within the context of standard cosmology, an accelerating universe requires the presence of a third `dark' component of energy, beyond matter and radiation. The available data, however, are still…
Fulvio MeliaDec 27, 2008
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Realistic analytic model for the prompt and high latitude emission in GRBs
Most gamma-ray bursts (GRBs) observed by the Swift satellite show an early rapid decay phase (RDP) in their X-ray lightcurve, which is usually a smooth continuation of the prompt gamma-ray emission,…
F. Genet, J. GranotDec 26, 2008
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Rapid pulsations in sub-THz solar bursts
A new solar burst emission spectral component has been found showing sub-THz fluxes increasing with frequency, spectrally separated from the well known microwave component. Rapid pulsations are found…
Pierre Kaufmann, C. Guillermo Gimenez de Castro, Emilia Correia et al.Dec 26, 2008
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Photometric Properties of the Near-contact Binary GW Geminorum
New multiband CCD photometry is presented for the eclipsing binary GW Gem; the RI light curves are the first ever compiled. Four new minimum timings have been determined. Our analysis of eclipse…
Jae Woo Lee, Seung-Lee Kim, Chung-Uk Lee et al.Dec 25, 2008
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