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Structural Parameters for Globular Clusters in NGC 5128. II. Hubble Space Telescope ACS Imaging and New Clusters
Forbes, Duncan A.; Barmby, Pauline; Harris, William E. +2 more
We report the first results from an imaging program with the ACS on the Hubble Space Telescope designed to measure the structural characteristics of a wide range of globular clusters in NGC 5128, the nearest giant elliptical galaxy. From 12 ACS WFC fields we have measured a total of 62 previously known globular clusters and have discovered 69 new …
Dynamical and chemical evolution of NGC 1569
Matteucci, F.; Recchi, S.; Hensler, G. +1 more
Blue Compact Dwarf and Dwarf Irregular galaxies are generally believed to be unevolved objects, due to their blue colors, compact appearance and large gas fractions. Many of these objects show an ongoing intense burst of star formation or have experienced it in the recent past. By means of 2-D hydrodynamical simulations, coupled with detailed chem…
Weak-lensing Detection at z ~ 1.3: Measurement of the Two Lynx Clusters with the Advanced Camera for Surveys
Ford, H. C.; Jee, M. J.; Illingworth, G. D. +4 more
We present a Hubble Space Telescope Advanced Camera for Surveys (ACS) weak-lensing study of RX J0849+4452 and RX J0848+4453, the two most distant (at z=1.26 and 1.27, respectively) clusters yet measured with weak lensing. The two clusters are separated by ~4' from each other and appear to form a supercluster in the Lynx field. Using our deep ACS i…
Larmor radius size density holes discovered in the solar wind upstream of Earth's bow shock
Dandouras, I.; Lucek, E.; Rème, H. +9 more
The Cluster and Double Star satellites recently observed plasma density holes upstream of Earth's collisionless bow shock to apogee distances of ∼19 and 13 earth radii, respectively. A survey of 147 isolated density holes using 4s time resolution data shows they have a mean duration of ∼17.9±10.4s, but holes as short as 4s are observed. The averag…
Multiwavelength Observations of EXO 0748-676. I. Reprocessing of X-Ray Bursts
Charles, P. A.; Horne, Keith; O'Brien, K. +5 more
We present high time-resolution multiwavelength observations of X-ray bursts in the low-mass X-ray binary UY Vol. Strong reprocessed signals are present in the ultraviolet and optical, lagged and smeared with respect to the X-rays. The addition of far-ultraviolet coverage for one burst allows much tighter constraints on the temperature and geometr…
Computational Acoustics in Spherical Geometry: Steps toward Validating Helioseismology
Christensen-Dalsgaard, J.; Schou, J.; Roth, M. +6 more
Throughout the past decade, detailed helioseismic analyses of observations of solar surface oscillations have led to advances in our knowledge of the structure and dynamics of the solar interior. Such analyses involve the decomposition of time series of the observed surface oscillation pattern into its constituent wave modes, followed by inversion…
Three-dimensional Simulation of Gamma-Ray Emission from Asymmetric Supernovae and Hypernovae
Maeda, Keiichi
Hard X- and γ-ray spectra and light curves resulting from radioactive decays are computed for aspherical (jetlike) and energetic supernova models (representing the prototypical hypernova SN 1998bw), using a three-dimensional energy- and time-dependent Monte Carlo scheme. The emission is characterized by (1) early emergence of high-energy emission,…
Gemini/GMOS spectra of globular clusters in the Virgo giant elliptical NGC 4649
Forbes, Duncan A.; Beasley, Michael A.; Zepf, Stephen E. +8 more
NGC 4649 (M60) is one of a handful of giant Virgo ellipticals. We have obtained Gemini/GMOS (Gemini North Multi-Object Spectrograph) spectra for 38 globular clusters (GCs) associated with this galaxy. Applying the multi-index χ2 minimization technique of Proctor and Sansom with the single stellar population models of Thomas, Maraston an…
Dwarf novae in the Hamburg quasar survey: rarer than expected
Gänsicke, B. T.; Hagen, H. -J.; Engels, D. +12 more
Aims.We report the discovery of five new dwarf novae that were spectroscopically identified in the Hamburg Quasar Survey (HQS), and discuss the properties of the sample of new dwarf novae from the HQS.
Methods.Follow-up time-resolved spectroscopy and photometry have been obtained to characterise the new systems.
Results.The orbital periods d…
XMM-Newton and Optical Follow-up Observations of SDSS J093249.57+472523.0 and SDSS J102347.67+003841.2
Anderson, Scott F.; Brinkmann, J.; Szkody, Paula +5 more
We report follow-up XMM-Newton and ground-based optical observations of the unusual X-ray binary SDSS J102347.67+003841.2 (=FIRST J102347.6+003841) and a new candidate intermediate polar (IP) found in the Sloan Digital Sky Survey: SDSS J093249.57+472523.0. SDSS J1023 was observed in its low state, with similar magnitude/color (V=17.4 and B=17.9) a…