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Astrophysics papers — page 152

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Dynamical mass of a star cluster in M83: a test of fibre-fed multi-object spectroscopy
(Abridged) Aims: We obtained VLT/FLAMES+UVES high-resolution, fibre-fed spectroscopy (FFS) of five young massive clusters in M83 (NGC 5236). This forms the basis of a pilot study testing the…
SL Moll, R de Grijs, P Anders et al.Aug 26, 2008
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Homologous Core Collapse in a Massive Star and Self-Similar Evolution of Rebound Shocks
During the gravitational core collapse of a massive progenitor star which may give rise to at least a class of gamma-ray bursts (GRBs) associated with supernovae, a stellar core rapidly passes…
Yi Cao, Yu-Qing LouAug 26, 2008
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X-Ray Afterglows
We summarise the X-ray temporal and spectral variability properties of GRBs as observed using the Swift satellite. Despite much individual complexity, the flux and spectral variability can be…
Paul O'Brien, Richard WillingaleAug 26, 2008
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A New Class of Radio Pulsars - Back in 1982
Basic ideas about the torques on the neutron star and the existence of an equilibrium rotation period followed from the recognition that most X-ray binaries contain accretion powered neutron stars.…
M. Ali AlparAug 26, 2008
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Constraints from deuterium on the formation of icy bodies in the Jovian system and beyond
We consider the role of deuterium as a potential marker of location and ambient conditions during the formation of small bodies in our Solar system. We concentrate in particular on the formation of…
Jonathan Horner, Olivier Mousis, Yann Alibert et al.Aug 26, 2008
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An oscillating, homogeneous and isotropic Universe from Scalar-Tensor gravity
An oscillating, homogeneous and isotropic Universe which arises from Scalar-Tensor gravity is discussed in the linearized approach, showing that some observative evidences like the Hubble Law and the…
Christian CordaAug 26, 2008
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BV photometry of a possible open star cluster pair NGC 7031/NGC 7086
We present a CCD BV photometry of the possible binary open star cluster NGC 7031/NGC 7086. The aim is to confirm or disprove their common nature on the grounds of their age and distance. An age of…
Valentin Kopchev, Georgy PetrovAug 26, 2008
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The X-ray luminosity of solar-mass stars in the intermediate age open cluster NGC 752
AIMS. While observational evidence shows that most of the decline in a star's X-ray activity occurs between the age of the Hyades (~8 x 108 yrs) and that of the Sun, very little is known about…
G. Giardino, I. Pillitteri, F. Favata et al.Aug 26, 2008
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Halo density reduction by baryonic settling?
We test the proposal by El-Zant et al that the dark matter density of halos could be reduced through dynamical friction acting on heavy baryonic clumps in the early stages of galaxy formation. Using…
J. R. Jardel, J. A. SellwoodAug 26, 2008
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The Hydrodynamics of Gamma-Ray Burst Remnants
This paper reports on the results of a numerical investigation designed to address how the initially anisotropic appearance of a GRB remnant is modified by the character of the circumburst medium and…
Enrico Ramirez-Ruiz, Andrew I. MacFadyenAug 26, 2008
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High-Resolution Observations of Molecular Lines toward the Hot Core G28.20-0.04N
We present the results from arcsecond resolution observations of various line transitions at 1.3 mm toward hypercompact HII region G28.20-0.04N. With the SMA data, we have detected and mapped the…
Sheng-Li Qin, Maohai Huang, Yuefang Wu et al.Aug 26, 2008
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Suzaku Observation of HESS J1825-137: Discovery of Largely-Extended X-rays near from PSR J1826-1334
We observed the brightest part of HESS J1825-137 with the Suzaku XIS, and found diffuse X-rays extending at least up to 15' (~ 17 pc) from the pulsar PSR J1826-1334. The spectra have no emission…
H. Uchiyama, H. Matsumoto, T. G. Tsuru et al.Aug 26, 2008
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LSST and the Dark Sector: Image Processing Challenges
Next generation probes of dark matter and dark energy require high precision reconstruction of faint galaxy shapes from hundreds of dithered exposures. Current practice is to stack the images. While…
J. A. Tyson, C. Roat, J. Bosch et al.Aug 26, 2008
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Dynamics of barred galaxies: effects of disk height
We study dynamics of bars in models of disk galaxies embeded in realistic dark matter halos. We find that disk thickness plays an important, if not dominant, role in the evolution and structure of…
A. Klypin, O. Valenzuela, P. Colin et al.Aug 26, 2008
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Substructures in hydrodynamical cluster simulations
The abundance and structure of dark matter subhalos has been analyzed extensively in recent studies of dark matter-only simulations, but comparatively little is known about the impact of baryonic…
K. Dolag, S. Borgani, G. Murante et al.Aug 25, 2008
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Radiative MHD simulation of sunspot structure
Results of a 3D MHD simulation of a sunspot with a photospheric size of about 20 Mm are presented. The simulation has been carried out with the MURaM code, which includes a realistic equation of…
M. Rempel, M. Schuessler, M. KnoelkerAug 25, 2008
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Quantitative analysis of clumps in the tidal tails of star clusters
Tidal tails of star clusters are not homogeneous but show well defined clumps in observations as well as in numerical simulations. Recently an epicyclic theory for the formation of these clumps was…
A. Just, P. Berczik, M. I. Petrov et al.Aug 25, 2008
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Gamma-Ray Studies of Blazars: Synchro-Compton Analysis of Flat Spectrum Radio Quasars
We extend a method for modeling synchrotron and synchrotron self-Compton radiations in blazar jets to include external Compton processes. The basic model assumption is that the blazar radio through…
Charles D. Dermer, Justin D. Finke, Hannah Krug et al.Aug 25, 2008
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Formation and Properties of Molecular Cloud Cores
In this paper, we review some of the properties of dense molecular cloud cores. The results presented here rely on three-dimensional numerical simulations of isothermal, magnetized, turbulent, and…
Sami Dib, Roberto Galvan-Madrid, Jongsoo Kim et al.Aug 25, 2008
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Common Proper Motion Companions to Nearby Stars: Ages and Evolution
A set of 41 nearby stars (closer than 25 pc) is investigated which have very wide binary and common proper motion (CPM) companions at projected separations between 1000 and 200 000 AU. These…
V. V. Makarov, N. Zacharias, G. S. HennessyAug 25, 2008
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Comprehensive Two-Point Analyses of Weak Gravitational Lensing Surveys
We present a framework for analyzing weak gravitational lensing survey data, including lensing and source-density observables, plus spectroscopic redshift calibration data. All two-point observables…
Gary M. BernsteinAug 25, 2008
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The Detection of Low Mass Companions in Hyades Cluster Spectroscopic Binary Stars
We have observed a large sample of spectroscopic binary stars in the Hyades Cluster, using high resolution infrared spectroscopy to detect low mass companions. We combine our double-lined infrared…
C. F. Bender, M. SimonAug 25, 2008
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Correlations of Prompt and Afterglow Emission in Swift Long and Short Gamma Ray Bursts
Correlation studies of prompt and afterglow emissions from gamma-ray bursts (GRBs) between different spectral bands has been difficult to do in the past because few bursts had comprehensive and…
N. Gehrels, S. D. Barthelmy, D. N. Burrows et al.Aug 25, 2008
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The Embedded Massive Star Forming Region RCW 38
RCW~38 is a uniquely young (<1 Myr), embedded (AV 10) stellar cluster surrounding a pair of early O stars (5.5) and is one of the few regions within 2 kpc other than Orion to contain…
Scott J. Wolk, Tyler L. Bourke, Miquela VigilAug 25, 2008
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The Ara OB 1a Association
The Ara OB1a association is one of the closest sites where triggered star formation is visible for multiple generations of massive stars. At about 1.3 kpc distance, it contains complex environments…
Scott J. Wolk, Fernando Comeron, Tyler BourkeAug 25, 2008
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