Search Publications
Chandra X-Ray Observations of Pictor A: High-Energy Cosmic Rays in a Radio Galaxy
Young, A. J.; Wilson, A. S.; Shopbell, P. L.
We report X-ray observations of the nearby, powerful radio galaxy Pictor A with the Chandra Observatory and optical and near-UV observations of its western radio hot spot with the Hubble Space Telescope. X-ray emission is detected from the nucleus, a 1.9‧ (110 kpc) long jet to the west of the nucleus, the western radio hot spot some 4.2‧ (240 kpc)…
Material Outflows from Coronal Intensity ``Dimming Regions'' during Coronal Mass Ejection Onset
Harra, Louise K.; Sterling, Alphonse C.
One signature of expulsion of coronal mass ejections (CMEs) from the solar corona is the appearance of transient intensity dimmings in coronal images. These dimmings have generally been assumed to be due to discharge of CME material from the corona, and thus the ``dimming regions'' are thought of as an important signature of the sources of CMEs. W…
The Aromatic Infrared Bands as seen by ISO-SWS: Probing the PAH model
Léger, A.; Moutou, C.; Giard, M. +6 more
We discuss the Aromatic Infrared Band (AIB) profiles observed by ISO-SWS towards a number of bright interstellar regions where dense molecular gas is illuminated by stellar radiation. Our sample spans a broad range of excitation conditions (exciting radiation fields with effective temperature, T_eff, ranging from 23 000 to 45 000 K). The SWS spect…
The Asymmetric Nebula Surrounding the Extreme Red Supergiant VY Canis Majoris
Smith, Nathan; Gehrz, Robert D.; Humphreys, Roberta M. +3 more
We present HST/WFPC2 images plus ground-based infrared images and photometry of the very luminous OH/IR star VY Canis Majoris. Our WFPC2 data show a complex distribution of knots and filamentary arcs in the asymmetric reflection nebula around the obscured central star. The reflection arcs may result from multiple, asymmetric ejection episodes due …
Dusty Debris around Solar-Type Stars: Temporal Disk Evolution
Zuckerman, B.; Silverstone, M. D.; Becklin, E. E. +2 more
Using ISO-ISOPHOT, we carried out a survey of almost 150 stars to search for evidence of emission from dust orbiting young main-sequence stars, both in clusters and isolated systems. Over half of the detections are new examples of dusty stellar systems and demonstrate that such dust can be detected around numerous stars older than a few times 10
The Origin of C IV Absorption Systems at Redshifts z < 1: Discovery of Extended C IV Envelopes around Galaxies
Chen, Hsiao-Wen; Lanzetta, Kenneth M.; Webb, John K.
We report the discovery of extended C IV gaseous envelopes around galaxies of a wide range of luminosity and morphological type. First, we show that C IV absorption systems are strongly clustered around galaxies on velocity scales of v<~250 km s-1 and impact parameter scales of ρ<~100 h-1 kpc, but not on larger velocity…
Complete and Simultaneous Spectral Observations of the Black Hole X-Ray Nova XTE J1118+480
Garnavich, P. M.; Groot, P. J.; Miller, J. M. +13 more
The X-ray nova XTE J1118+480 suffers minimal extinction (b=62deg) and therefore represents an outstanding opportunity for multiwavelength studies. Hynes et al. conducted the first such study, which was centered on 2000 April 8 using UKIRT, EUVE, HST, and RXTE. On 2000 April 18, the Chandra X-Ray Observatory obtained data coincident with…
A Serendipitous Galaxy Cluster Survey with XMM: Expected Catalog Properties and Scientific Applications
Romer, A. Kathy; Viana, Pedro T. P.; Liddle, Andrew R. +1 more
This paper describes a serendipitous galaxy cluster survey that we plan to conduct with the XMM X-ray satellite. We have modeled the expected properties of such a survey for three different cosmological models, using an extended Press-Schechter formalism combined with a detailed characterization of the expected capabilities of the European Photon …
Measuring cluster temperature profiles with XMM/EPIC
Aghanim, N.; Arnaud, M.; Hughes, J. P. +3 more
Using the PV observation of A1795, we illustrate the capability of XMM-EPIC to measure cluster temperature profiles, a key ingredient for the determination of cluster mass profiles through the equation of hydrostatic equilibrium. We develop a methodology for spatially resolved spectroscopy of extended sources, adapted to XMM background and vignett…
The Chandra Deep Survey of the Hubble Deep Field North Area. IV. An Ultradeep Image of the HDF-N
Hornschemeier, A. E.; Alexander, D. M.; Brandt, W. N. +7 more
We present results from a 479.7 ks Chandra exposure of the Hubble Deep Field North (HDF-N) and its immediate vicinity. In this X-ray image, the deepest ever reported with a 0.5-2.0 keV flux limit of ~4.9×10-17 ergs cm-2 s-1, four new HDF-N X-ray sources are detected, bringing the total number of such sources to 12.…