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Evidence of an Untruncated Accretion Disk in the Broad-Line Radio Galaxy 4C 74.26
Fabian, A. C.; Ballantyne, D. R.
We present evidence of a broad ionized Fe Kα line in the XMM-Newton spectrum of the broad-line radio galaxy (BLRG) 4C 74.26. This is the first indication that the innermost regions of the accretion flow in BLRGs contain thin, radiatively efficient disks. Analysis of the 35 ks XMM-Newton observation finds a broad line with an inner radius close to …
A Redshift z ~ 5.4 Lyα Emitting Galaxy with Linear Morphology in the GRAPES/Hubble Ultra Deep Field
Gardner, Jonathan P.; Stiavelli, Massimo; Daddi, Emanuele +21 more
We have discovered an extended Lyα plume (UDF 5225) associated with a compact source at redshift z~5.4 in slitless spectroscopic data from the Grism ACS Program for Extragalactic Science (GRAPES) project. The spatial extent of the emission is about 6×1.5 kpc (1''×0.25"). Combining our grism data and the broadband images from the Hubble …
M74 X-1 (CXOU J013651.1+154547): An Extremely Variable Ultraluminous X-Ray Source
Roberts, T. P.; Krauss, M. I.; Kilgard, R. E. +2 more
Ultraluminous X-ray sources (ULXs) have been described variously as the most luminous normal X-ray binaries, hypernovae, and ``intermediate-mass'' black holes with masses of hundreds to thousands of solar masses. We present results on M74 X-1 (CXOU J013651.1+154547), a ULX in the nearby spiral galaxy M74 (NGC 628), from observations by Chandra and…
The High-Energy Spectrum of NGC 4151
Gehrels, N.; Petrucci, P. -O.; Shrader, C. R. +5 more
We present the first INTEGRAL observations of the type 1.5 Seyfert galaxy NGC 4151. Combining several INTEGRAL observations performed during 2003, totaling ~400 ks of exposure time, allows us to study the spectrum in the 2-300 keV range. The measurements presented here reveal an overall spectrum from X-rays up to soft gamma-rays that can be descri…
Coronal Mass Ejections and Galactic Cosmic-Ray Modulation
Gopalswamy, N.; Yashiro, S.; Lara, A. +3 more
We present a study of the long-term evolution of coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronograph (LASCO) on board SOHO during the ascending, maximum, and part of the descending phases of solar cycle 23 and their relation with the modulation of galactic cosmic-ray (GCR) intensity observed at 1 AU by the Clima…
Atmospheres and Plasma Interactions at Saturn's Largest Inner Icy Satellites
Saur, Joachim; Strobel, Darrell F.
We explore the possible existence of atmospheres on Saturn's icy satellites, Mimas, Enceladus, Tethys, Dione, and Rhea. Only the most massive satellite, Rhea, has the potential to hold a thin oxygen atmosphere/exosphere. The masses of the other satellites are too small to retain gravitationally atmospheres in the presence of large thermal escape r…
Models of Five Absorption-Line Systems along the Line of Sight Toward PG 0117+213
Charlton, Jane C.; Masiero, Joseph R.; Churchill, Christopher W. +2 more
We present our investigation into the physical conditions of the gas in five intervening quasar absorption-line systems along the line of sight toward the quasar PG 0117+213, with redshifts of z=0.57, 0.72, 1.04, 1.32, and 1.34. Photoionization modeling of Hubble Space Telescope, Keck I, and Palomar data, using the code Cloudy, is employed to deri…
A Starfish Preplanetary Nebula: IRAS 19024+0044
Sahai, Raghvendra; Sánchez Contreras, Carmen; Morris, Mark
Using the Hubble Space Telescope, we have imaged the OH/IR star IRAS 19024+0044 (I19024) at 0.6, 0.8, 1.1, and 1.6 µm, as part of our surveys of candidate preplanetary nebulae. The images show a multipolar nebula of size ~3.7"×2.3", with at least six elongated lobes emanating from the center of the nebula. Two of the lobes show limb-brighten…
Diffuse X-Rays from the Arches and Quintuplet Clusters
Melia, Fulvio; Wang, Q. Daniel; Rockefeller, Gabriel +1 more
The origin and initial mass function of young stellar clusters near the Galactic center are still poorly understood. Two of the more prominent ones, the Arches and Quintuplet clusters, may have formed from a shock-induced burst of star formation, given their similar age and proximity to each other. Their unusual mass distribution, however, may be …
The Discovery of More than 2000 White Dwarfs in the Globular Cluster ω Centauri
Prada Moroni, P. G.; Pulone, L.; Stetson, P. B. +9 more
We present deep multiband (F435W, F625W, and F658N) photometric data of the globular cluster ω Cen collected with the Advanced Camera for Surveys on board the Hubble Space Telescope. We identified in the (F435W - F625W, F435W)-plane more than 2000 white dwarf (WD) candidates using three out of nine available pointings. Such a large sample appears …