Search Publications
Physical Conditions in the Interstellar Medium toward HD 185418
Abel, N. P.; Ferland, G. J.; Srianand, R. +1 more
We have developed a complete model of the hydrogen molecule as part of the spectral simulation code Cloudy. Our goal is to apply this to spectra of high-redshift star-forming regions where H2 absorption is seen, but where few other details are known, to understand its implication for star formation. The microphysics of H2 is …
A Study of the Orientation of Interplanetary Magnetic Clouds and Solar Filaments
Wang, Yuming; Wang, Jingxiu; Wang, S. +2 more
As a kind of eruptive phenomenon associated with coronal mass ejections (CMEs), solar eruptive filaments are thought to be parallel to the axis of surrounding arcade coronal magnetic fields that erupt and develop into interplanetary magnetic clouds (MCs). By investigating three events from 2000 August, 2003 October, and 2003 November, we estimate …
XMM-Newton Observation of Diffuse Gas and Low-Mass X-Ray Binaries in the Elliptical Galaxy NGC 4649 (M60)
Sarazin, Craig L.; Irwin, Jimmy A.; Randall, Scott W.
We present an XMM-Newton X-ray observation of the X-ray-bright E2 elliptical galaxy NGC 4649. In addition to bright diffuse emission, we resolve 158 discrete sources, ~50 of which are likely to be LMXBs associated with NGC 4649. We find evidence for variability in three sources between this observation and a previous Chandra observation. Additiona…
Spectral States of the X-Ray Binary IGR J17091-3624 Observed by INTEGRAL and RXTE
Capitanio, F.; Bird, A. J.; Ubertini, P. +6 more
IGR J17091-3624 was discovered in 2003 April by IBIS, the gamma-ray imager on board the INTEGRAL satellite, during its Galactic Center Deep Exposure program. The source was initially detectable only in the 40-100 keV range but after 2 days was also detected in the 15-40 keV range. Its flux had by then increased to 40 and 25 mcrab in the 15-40 and …
Ultracompact Blue Dwarf Galaxies: Hubble Space Telescope Imaging and Stellar Population Analysis
Somerville, Rachel S.; Windhorst, Rogier A.; Vacca, William D. +3 more
We present deep Hubble Space Telescope (HST) Advanced Camera for Surveys/High Resolution Channel U-, narrow-V-, and I-band images of nine ``ultracompact'' blue dwarf galaxies (UCBDs) selected from the Sloan Digital Sky Survey (SDSS). We define UCBDs as local (z<0.01) star-forming galaxies having angular diameters less than 6" and physical diame…
High-Resolution Infrared Imaging of Herschel 36 SE: A Showcase for the Influence of Massive Stars in Cluster Environments
Pascucci, I.; Stecklum, B.; Henning, Th. +4 more
We present high-resolution infrared imaging of the massive star-forming region around the O star Herschel 36. Special emphasis is given to a compact infrared source at 0.25" southeast of the star. The infrared source, hereafter Her 36 SE, is extended in the broadband images but features spatially unresolved Brγ line emission. The line-emission sou…
The Binary Nucleus in VCC 128: A Candidate Supermassive Black Hole in a Dwarf Elliptical Galaxy
Pasquali, Anna; Seth, Anil; Debattista, Victor P. +3 more
Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) images of the Virgo Cluster dwarf elliptical galaxy VCC 128 reveal an apparently double nucleus. The two components, which are separated by ~32 pc in projection, have the same magnitude and color. We present a spectrum of this double nucleus and show that it is inconsistent with on…
Low Radiative Efficiency Accretion at Work in Active Galactic Nuclei: The Nuclear Spectral Energy Distribution of NGC 4565
Macchetto, F. D.; Gilli, R.; Sparks, William B. +1 more
We derive the spectral energy distribution (SED) of the nucleus of the Seyfert galaxy NGC 4565. Despite its classification as a Seyfert 2, the nuclear source is substantially unabsorbed. The absorption we find from Chandra data (NH=2.5×1021 cm-2) is consistent with that produced by material in the galactic disk of …
High-Energy Particles in the Wind Nebula of Pulsar B1509-58 as Seen by INTEGRAL
Goret, P.; Laurent, P.; Kuiper, L. +5 more
We present observations with the INTEGRAL IBIS telescope of the wind nebula powered by the young pulsar B1509-58, and we discuss the spatial and spectral properties of the unpulsed emission in the 20-200 keV energy band. The source extension and orientation along the northwest-southeast axis correspond to the jet emission seen at keV and TeV energ…
Far-Ultraviolet and X-Ray Observations of the Reverse Shock in the Small Magellanic Cloud Supernova Remnant 1E 0102.2-7219
Blair, William P.; Sasaki, Manami; Smith, Randall K. +4 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) and X-Ray Multi-Mirror Mission (XMM-Newton) data for the reverse shock of the O-rich supernova remnant (SNR) 1E 0102.2-7219 in the Small Magellanic Cloud (SMC). The FUSE observations cover three regions with significantly different optical [O III] intensities, all associated with the relativ…