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The Recent Star Formation Histories of M81 Group Dwarf Irregular Galaxies
Cannon, John M.; Dolphin, Andrew E.; Skillman, Evan D. +4 more
We present observations and analysis of nine dwarf irregular galaxies (dIs) in the M81 Group taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope. The nine galaxies (the Garland, M81 Dwarf A, DDO 53, Ho IX, Ho I, DDO 165, NGC 2366, Ho II, and IC 2574) span 6 mag in luminosity, a factor of 1000 in current star formation rate…
The Fermi Gamma-Ray Space Telescope Discovers the Pulsar in the Young Galactic Supernova Remnant CTA 1
Ozaki, M.; Caraveo, P. A.; Orlando, E. +182 more
Energetic young pulsars and expanding blast waves [supernova remnants (SNRs)] are the most visible remains after massive stars, ending their lives, explode in core-collapse supernovae. The Fermi Gamma-Ray Space Telescope has unveiled a radio quiet pulsar located near the center of the compact synchrotron nebula inside the supernova remnant CTA 1. …
Solid tidal friction above a liquid water reservoir as the origin of the south pole hotspot on Enceladus
Sotin, C.; Tobie, G.; Čadek, O.
Earth, Jupiter's moon Io and Saturn's tiny moon Enceladus are the only solid objects in the Solar System to be sufficiently geologically active for their internal heat to be detected by remote sensing. Interestingly, the endogenic activity on Enceladus is only located on a specific region at the south pole, from which jets of water vapor and ice p…
Strong horizontal photospheric magnetic field in a surface dynamo simulation
Schüssler, M.; Vögler, A.
Context: Observations with the Hinode spectro-polarimeter have revealed strong horizontal internetwork magnetic fields in the quiet solar photosphere.
Aims: We aim to interpret the observations with results from numerical simulations.
Methods: Radiative MHD simulations of dynamo action by near-surface convection are analyzed with respect t…
Extrasolar Giant Planets and X-Ray Activity
Drake, Jeremy J.; Kashyap, Vinay L.; Saar, Steven H.
We have carried out a survey of X-ray emission from stars with giant planets, combining both archival and targeted surveys. Over 230 stars have been currently identified as possessing planets, and roughly one-third of these have been detected in X-rays. We carry out detailed statistical analysis on a volume-limited sample of main-sequence star sys…
The evolution of the brightest cluster galaxies since z ~ 1 from the ESO Distant Cluster Survey (EDisCS)
Milvang-Jensen, B.; Noll, S.; Poggianti, B. M. +13 more
We present K-band data for the brightest cluster galaxies (BCGs) from the ESO Distant Cluster Survey (EDisCS). These data are combined with the photometry published by Aragón-Salamanca, Baugh & Kauffmann and a low-redshift comparison sample built from the BCG catalogue of von der Linden et al. BCG luminosities are measured inside a metric circ…
High variability in Vela X-1: giant flares and off states
Santangelo, A.; Wilms, J.; Ferrigno, C. +6 more
Aims: We investigate the spectral and temporal behavior of the high mass X-ray binary Vela X-1 during a phase of high activity, with special focus on the observed giant flares and off states.
Methods: INTEGRAL observed Vela X-1 in a long almost uninterrupted observation for two weeks in 2003 Nov/Dec. The data were analyzed with OSA 7.0 and FTO…
Ion and neutral sources and sinks within Saturn's inner magnetosphere: Cassini results
Thomsen, M. F.; Johnson, R. E.; Hartle, R. E. +16 more
Using ion-electron fluid parameters derived from Cassini Plasma Spectrometer (CAPS) observations within Saturn's inner magnetosphere as presented in Sittler et al. [2006a. Cassini observations of Saturn's inner plasmasphere: Saturn orbit insertion results. Planet. Space Sci., 54, 1197-1210], one can estimate the ion total flux tube content, N…
Multiwavelength Observations of the Powerful Gamma-Ray Quasar PKS 1510-089: Clues on the Jet Composition
Kataoka, J.; Kawai, N.; Tosti, G. +16 more
We present the results from a multiwavelength campaign conducted in 2006 August of the powerful γ-ray quasar PKS 1510-089 (z = 0.361). This campaign commenced with a deep Suzaku observation lasting 3 days for a total exposure time of 120 ks and continued with Swift monitoring over 18 days. Besides Swift observations, the campaign included ground-b…
The Physical Scale of the Far-Infrared Emission in the Most Luminous Submillimeter Galaxies
Wilner, David J.; Yun, Min S.; Fazio, Giovanni G. +10 more
We present high-resolution submillimeter interferometric imaging of two of the brightest high-redshift submillimeter galaxies known: GN 20 and AzTEC1 at 0.8'' and 0.3'' resolution, respectively. Our data—the highest resolution submillimeter imaging of high-redshift sources accomplished to date—were collected in three different array configurations…