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Astrophysics papers — page 62

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Trigonometric Parallaxes of Massive Star Forming Regions: IV. G35.20-0.74 and G35.20-1.74
We report trigonometric parallaxes for the high-mass star forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19 (+0.24 -0.20) kpc and 3.27 (+0.56 -0.42) kpc, respectively.…
B. Zhang, X. W. Zheng, M. J. Reid et al.Nov 5, 2008
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Trigonometric Parallaxes of Massive Star Forming Regions: III. G59.7+0.1 and W 51 IRS2
We report trigonometric parallaxes for G59.7+0.1 and W 51 IRS2, corresponding to distances of 2.16+0.10-0.09 kpc and 5.1+2.9-1.4 kpc, respectively. The distance to G59.7+0.1 is smaller…
Y. Xu, M. J. Reid, K. M. Menten et al.Nov 5, 2008
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The total mass of the early-type galaxy NGC 4649 (M60)
In this paper we analyze the problem of the total mass and the total mass-to-light ratio of the early-type galaxy NGC 4649 (M60). We have used two independent techniques: the X-ray methodology which…
S. Samurovic, M. M. CirkovicNov 5, 2008
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MOND vs. Newtonian dynamics in early-type galaxies. The case of NGC 4649 (M60)
Context: Regarding the significant interest in both dark matter and the application of MOND to early-type galaxies, we investigate the MOND theory by comparing its predictions, for models of constant…
S. Samurovic, M. M. CirkovicNov 5, 2008
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Status of neutrino astronomy
Astrophysical neutrinos can be produced in proton interactions of charged cosmic rays with ambient photon or baryonic fields. Cosmic rays are observed in balloon, satellite and air shower experiments…
Julia K. BeckerNov 5, 2008
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Estimating the solar meridional circulation by normal mode decomposition
The objective of this article is to use Fourier-Hankel decomposition as suggested earlier by Braun & Fan (1998) to estimate the integrated horizontal meridional flow velocity as a function of mode…
Lars Krieger, Markus Roth, Oskar von der LueheNov 5, 2008
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X-Ray Spectral Variability of the Seyfert Galaxy NGC 4051 Observed with Suzaku
We report results from a Suzaku observation of the narrow-line Seyfert 1 NGC 4051. During our observation, large amplitude rapid variability is seen and the averaged 2--10 keV flux is 8.1x10-12 erg…
Y. Terashima, L. C. Gallo, H. Inoue et al.Nov 5, 2008
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NLTE abundances of Mn in a sample of metal-poor stars
Following our solar work, we perform NLTE calculations of the Mn abundance for fourteen stars with [Fe/H] from 0 to -2.5, mainly to show how NLTE affects Mn abundances in cool stars of different…
Maria Bergemann, Thomas GehrenNov 5, 2008
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Trigonometric Parallaxes of Massive Star Forming Regions: II. Cep A & NGC 7538
We report trigonometric parallaxes for the sources NGC 7538 and Cep A, corresponding to distances of 2.65 [+0.12/-0.11] kpc and 0.70 [+0.04/-0.04] kpc, respectively. The distance to NGC 7538 is…
L. Moscadelli, M. J. Reid, K. M. Menten et al.Nov 5, 2008
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Planet formation in the habitable zone of alpha Centauri B
Recent studies have shown that alpha Centauri B might be, from an observational point of view, an ideal candidate for the detection of an Earth-like planet in or near its habitable zone (0.5-0.9AU).…
Philippe Thebault, Francesco Marzari, Hans SchollNov 5, 2008
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Effects of Rotation on Standing Accretion Shock Instability in Nonlinear Phase for Core-Collapse Supernovae
We studied the effects of rotation on standing accretion shock instability (SASI) by performing three-dimensional hydrodynamics simulations. Taking into account a realistic equation of state and…
Wakana Iwakami, Kei Kotake, Naofumi Ohnishi et al.Nov 5, 2008
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Period changes in six contact binaries: WZ And, V803 Aql, DF Hya, PY Lyr, FZ Ori, and AH Tau
Six contact binaries lacking a period analysis have been chosen to search for the presence of a third body. The O-C diagrams of these binaries were analyzed with the least-squares method by using all…
P. Zasche, A. Liakos, P. Niarchos et al.Nov 5, 2008
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Infrared Spectroscopy of Symbiotic Stars. VII. Binary Orbit and Long Secondary Period Variability of CH Cygni
High-dispersion spectroscopic observations are used to refine orbital elements for the symbiotic binary CH Cyg. The current radial velocities, added to a previously published 13 year time series of…
Kenneth Hinkle, Francis Fekel, Richard JoyceNov 5, 2008
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Parity violation constraints using 2006-2007 QUaD CMB polarization spectra
We constrain parity-violating interactions to the surface of last scattering using spectra from the QUaD experiment's second and third seasons of observations by searching for a possible…
QUaD Collaboration, E. Y. S. Wu, P. Ade et al.Nov 4, 2008
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Self calibration of gravitational shear-galaxy intrinsic ellipticity correlation in weak lensing surveys
The galaxy intrinsic alignment is a severe challenge to precision cosmic shear measurement. We propose to self-calibrate the induced gravitational shear-galaxy intrinsic ellipticity correlation (the…
Pengjie ZhangNov 4, 2008
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The Anisotropic Spatial Distribution of Hypervelocity Stars
We study the distribution of angular positions and angular separations of unbound hypervelocity stars (HVSs). HVSs are spatially anisotropic at the 3-sigma level. The spatial anisotropy is…
Warren R. Brown, Margaret J. Geller, Scott J. Kenyon et al.Nov 4, 2008
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Cosmological electromagnetic fields and dark energy
We show that the presence of a temporal electromagnetic field on cosmological scales generates an effective cosmological constant which can account for the accelerated expansion of the universe.…
Jose Beltran Jimenez, Antonio L. MarotoNov 4, 2008
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Galaxy evolution from strong lensing statistics: the differential evolution of the velocity dispersion function in concord with the LambdaCDM paradigm
We study galaxy evolution from z=1 to z=0 as a function of velocity dispersion sigma for galaxies with sigma > 95 km/s based on the measured and Monte Carlo realised local velocity dispersion…
Kyu-Hyun ChaeNov 4, 2008
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A New Numerical Technique to Determine Primary Cosmic Ray Composition in the Ankle Region
In this paper we introduce a new multiparametric technique that attempts to tackle simultaneously the problems of composition determination and hadronic interaction uncertainty. Employing simulations…
A. D. Supanitsky, G. Medina-Tanco, A. EtchegoyenNov 4, 2008
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Machine learning techniques for astrophysical modelling and photometric redshift estimation of quasars in optical sky surveys
Machine learning techniques are utilised in several areas of astrophysical research today. This dissertation addresses the application of ML techniques to two classes of problems in astrophysics,…
N. Daniel KumarNov 4, 2008
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The Spectral Shape and Photon Fraction as Signatures of the GZK-Cutoff
With the prospect of measuring the fraction of arriving secondary photons, produced through photo-pion energy loss interactions of ultra high energy cosmic ray (UHECR) protons with the microwave…
Andrew M. Taylor, Felix A. AharonianNov 4, 2008
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Systematic thermal reduction of neutronization in core-collapse supernovae
We investigate to what extent the temperature dependence of the nuclear symmetry energy can affect the neutronization of the stellar core prior to neutrino trapping during gravitational collapse. To…
A. F. Fantina, P. Donati, P. M. PizzocheroNov 4, 2008
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Sky-maps of the sidereal anisotropy of galactic cosmic ray intensity and its energy dependence
We analyze the sidereal daily variations observed between 1985 and 2006 at Matsushiro, Japan (MAT) and between 1993 and 2005 at Liapootah, Tasmania (LPT). These stations comprise the two hemisphere…
K. Munakata, N. Matsumoto, S. Yasue et al.Nov 4, 2008
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Absorption line indices in the UV. Empirical and theoretical stellar population models
(Abridged). Stellar absorption lines in the optical have been extensively studied and constitute an important stellar population diagnostic for galaxies in the local universe and up to moderate…
C. Maraston, L. A. Nieves, R. Bender et al.Nov 4, 2008
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The Variable Reflection Nebula Cepheus A East
We report K'-band imaging observations of the reflection nebula associated with Cepheus A East covering the time interval from 1990 to 2004. Over this time the reflection nebula shows variations…
Klaus W. Hodapp, Eli BressertNov 4, 2008
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