Search Publications
BeppoSAX observations of Narrow-Line Seyfert 1 galaxies. II. Ionized iron features in Arakelian 564
Brandt, W. N.; Fiore, F.; Guainazzi, M. +8 more
The BeppoSAX observations of the bright Narrow-Line Seyfert 1 galaxy Ark 564 are presented along with a high quality optical spectrum taken at the 1.5 m telescope at La Silla. The 0.1-10 keV X-ray spectrum is characterized by a strong soft component which is best described by blackbody-like emission with a temperature of ~ 160 eV. At higher energi…
The impact of bars on the mid-infrared dust emission of spiral galaxies: global and circumnuclear properties
Roussel, H.; Sauvage, M.; Madden, S. +6 more
We study the mid-infrared properties of a sample of 69 nearby spiral galaxies, selected to avoid Seyfert activity contributing a significant fraction of the central energetics, or strong tidal interaction, and to have normal infrared luminosities. These observations were obtained with ISOCAM, which provides an angular resolution of the order of 10…
The Main-Sequence Luminosity Function of Palomar 5 from THE HUBBLE SPACE TELESCOPE
Smith, Graeme H.; Grillmair, Carl J.
A low mass, large core radius, low central concentration, and strong tidal tails suggest that the globular cluster Palomar 5 has lost a large fraction of its initial mass over time. If the dynamical evolution of Pal 5 has been dominated by the effects of mass loss, then theoretical arguments suggest that the luminosity function should be deficient…
Coronal Inflows and the Sun's Nonaxisymmetric Open Flux
Sheeley, N. R., Jr.; Wang, Y. -M.; Knudson, T. N.
Wang et al. recently described white-light coronagraph observations of faint coronal features moving inward toward the Sun at heliocentric distances of 2-6 Rsolar. In a study of these inflows during 1996-2000, we have found that they occur along bends of the coronal streamer belt and are especially common when the magnetic field has a f…
Coordinated 1996 HST and IRTF Imaging of Neptune and Triton. II. Implications of Disk-Integrated Photometry
Baines, K. H.; Sromovsky, L. A.; Fry, P. M. +1 more
Near-IR groundbased observations coordinated with Wide Field Planetary Camera 2 (WFPC2) HST observations (Sromovsky et al.Icarus149, 416-434, 459-488) provide new insights into the variations of Neptune and Triton over a variety of time scales. From 1996 WFPC2 imaging we find that a broad circumpolar nonaxisymmetric dark band dominates Neptune's l…
Double Loop Configuration of a Flaring Region from Microwave, Extreme-Ultraviolet, and X-Ray Imaging Data
Kundu, M. R.; White, S. M.; Grechnev, V. V. +1 more
We use extensive multiwavelength data to study a flare belonging to the interacting-loop class of events identified by Hanaoka. The class of flares is identified morphologically from the presence of two well-separated radio sources in 17 GHz images (in this event, 160" apart), with only one source showing soft X-ray emission. This event shows many…
Hubble Space Telescope Images of the Ultraluminous Supernova Remnant Complex in NGC 6946
Blair, William P.; Fesen, Robert A.; Schlegel, Eric M.
We present Hubble Space Telescope (HST) narrow-passband Hα and [S II] images and broadband continuum images of the region around an extremely luminous optical and X-ray supernova remnant complex in the spiral galaxy NGC 6946. These images, obtained with the PC1 CCD of the Wide Field Planetary Camera 2, show a circular, limb-brightened shell of dia…
Kinematics of Molecular Hydrogen Emission from Pre-Planetary Nebulae: RAFGL 2688 and RAFGL 618
Kastner, Joel H.; Weintraub, David A.; Gatley, Ian +1 more
We present high spectral resolution maps of near-infrared molecular hydrogen emission from the bipolar pre-planetary nebulae RAFGL 2688 and RAFGL 618, obtained with the NOAO Phoenix spectrometer. The measured velocity gradients along the polar axes of both nebulae indicate that the highest velocity gas lies closest to the central stars. These resu…
Charge-equilibration of Fe ions accelerated in a hot plasma
Torsti, J.; Kocharov, L.; Kovaltsov, G. A. +2 more
We examine the energy-dependent rates of charge-changing processes of energetic Fe ions in the hot plasma of the solar corona. For ionization of the Fe-ion projectile in collisions with ambient protons, three different methods of estimating the corresponding ionization cross sections are presented and compared. Proton-impact ionization is found to…
A Massive Disk Galaxy at z=1.34
van Dokkum, Pieter G.; Stanford, S. A.
We report on the discovery of a rapidly rotating disk in a K-selected galaxy at z=1.34. Spatially resolved kinematics are determined from deep, moderate-resolution Keck spectroscopy covering the redshifted [O II] 3727 Å line. A conservative estimate of the maximum rotation velocity Vmax=290+/-20 km s-1, placing the galaxy amo…