Search Publications
X-Raying A2125: A Large-Scale Hierarchical Complex of Galaxies and Hot Gas
Wang, Q. Daniel; Owen, Frazer; Ledlow, Michael
We present an 82 ks Chandra ACIS-I observation of a large-scale hierarchical complex, which consists of various clusters/groups of galaxies and low surface brightness X-ray emission at z=0.247. This high-resolution Chandra observation allows us for the first time to separate unambiguously the X-ray contributions from discrete sources and large-sca…
Molecular gas in NUclei of GAlaxies (NUGA). II. The ringed LINER NGC 7217
Tacconi, L. J.; Hunt, L. K.; Schinnerer, E. +8 more
We present CO(1-0) and CO(2-1) maps of the LINER galaxy NGC 7217, obtained with the IRAM interferometer, at 2.4 arcsec×1.9 arcsec and 1.2 arcsec×0.8 arcsec resolution respectively. The nuclear ring (at r=12 arcsec=0.8 kpc) dominates the CO maps, and has a remarkable sharp surface density gradient at its inner edge. The latter is the site of the st…
A thorough study of the intriguing X-ray emission from the Cartwheel ring
Wolter, A.; Trinchieri, G.
We present the results from the high resolution Chandra observation of the
Thin electron-scale layers at the magnetopause
Fazakerley, A. N.; André, M.; Vaivads, A. +2 more
We use data from the four Cluster satellites to examine the microphysics of a thin electron-scale layer discovered on the magnetospheric side of the magnetopause. Here the ion and electron motions are decoupled in a layer about 20 km (a few electron scales) wide, including currents and strong electric fields. In this layer the electrons are E × B …
Coronal versus photospheric abundances of stars with different activity levels
Sanz-Forcada, J.; Micela, G.; Favata, F.
We report a detailed analysis of the coronal abundance of 4 stars with varying levels of activity and with accurately known photospheric abundances. The coronal abundance is determined here using a line flux analysis and a full determination of the differential emission measure. Photospheric abundance values are taken from the literature. Previous…
C II Radiative Cooling of the Diffuse Gas in the Milky Way
Savage, B. D.; Wakker, B. P.; Lehner, N.
The heating and cooling of the interstellar medium (ISM) allow the gas in the ISM to coexist at very different temperatures in thermal pressure equilibrium. The rate at which the gas cools or heats is therefore a fundamental ingredient for any theory of the ISM. The heating cannot be directly determined, but the cooling can be inferred from observ…
Dramatic X-Ray Spectral Variability of the Broad Absorption Line Quasar PG 2112+059
Brandt, W. N.; Chartas, G.; Gallagher, S. C. +3 more
With a 1999 ASCA observation, PG 2112+059 became notable as the first broad absorption line (BAL) quasar found to exhibit a typical radio-quiet quasar X-ray continuum underlying a large amount of intrinsic absorption. We present a recent Chandra ACIS-S3 observation of PG 2112+059 that demonstrates remarkable spectral and luminosity variability sin…
The First Detailed X-Ray Observations of High-Redshift, Optically Selected Clusters: XMM-Newton Results for Cl 1324+3011 at z = 0.76 and Cl 1604+4304 at z = 0.90
Mulchaey, John S.; Postman, Marc; Lubin, Lori M.
We present the first detailed X-ray observations of optically selected clusters at high redshift. Two clusters, Cl 1324+3011 at z=0.76 and Cl 1604+4304 at z=0.90, were observed with XMM-Newton. The opticenter of each cluster is coincident with an extended X-ray source whose emission is detected out to a radius of ~0.5 h-170 M…
Hubble Space Telescope STIS Far-Ultraviolet Observations of the Central Nebulae in the Cooling-Core Clusters A1795 and A2597
Koekemoer, Anton M.; Baum, Stefi A.; Mack, Jennifer +2 more
We present Hubble Space Telescope STIS FUV images of the Lyα and FUV continuum emission of the luminous emission-line nebulae in two cooling-core clusters, A1795 and A2597. The Lyα and FUV continuum emission consist of a diffuse component (~60%) and more compact features (knots and filaments), which lie preferentially along the radio source edges.…
The Progenitor of the Type II-P SN 2004dj in NGC 2403
Bond, Howard E.; Maoz, D.; Ofek, E. O. +4 more
The Type II-P supernova SN 2004dj in the nearby galaxy NGC 2403 occurred at a position coincident with object 96 in the list of luminous stars and clusters in this galaxy published by Sandage in 1984. The coincidence is established definitively through astrometric registration of our ground-based archival images of NGC 2403 with our recent images …