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The XMM-LSS survey. The XMDS/VVDS 4σ catalogue
Maccagni, D.; Maraschi, L.; Chiappetti, L. +15 more
We present a first catalogue of X-ray sources resulting from the central area of the XMM-LSS (Large Scale Structure survey). We describe the reduction procedures and the database tools we developed and used to derive a well defined catalogue of X-ray sources. The present catalogue is limited to a sub-sample of 286 sources detected at 4 σ in the 1 …
The Role of Magnetic Helicity in Coronal Mass Ejections
MacNeice, P. J.; Antiochos, S. K.; Phillips, A. D.
We investigate the factors responsible for initiating coronal mass ejections (CMEs), specifically, the role of magnetic helicity. Using numerical simulations of the breakout model for CMEs, we show that eruption occurs at a fixed magnitude of free energy in the corona, independent of the value of helicity. Almost identical eruptions are obtained f…
Detection and Diagnostics of a Coronal Shock Wave Driven by a Partial-Halo Coronal Mass Ejection on 2000 June 28
Raymond, J. C.; Ciaravella, A.; Li, J. +2 more
A fast partial-halo coronal mass ejection (CME) was observed on 2000 June 28 by instruments on the SOHO spacecraft. The CME leading edge and filamentary cold core were detected over the northwest limb at 2.32 Rsolar by the SOHO UV Coronagraph Spectrometer (UVCS). The broad profile of the O VI λ1032 line gives evidence of a shock front a…
Red Thick Disks of Nearby Galaxies
Mould, Jeremy
Edge-on systems reveal the properties of disk galaxies as a function of height, z, above the plane. Four local edge-on galaxies that are close enough to have been resolved into stars by the Hubble Space Telescope show thick disks composed of a red stellar population that is old and relatively metal rich. Color gradients, Δ(V-I)/Δz, are zero or sli…
The Lens Redshift and Galaxy Environment for HE 0435-1223
Pevunova, O.; Kochanek, C. S.; Morgan, N. D. +1 more
The redshift of the galaxy lensing HE 0435-1223 is 0.4546+/-0.0002, based on observations obtained with the Low Dispersion Survey Spectrograph 2 on the Magellan Consortium's 6.5 m Clay Telescope. Hubble Space Telescope Advanced Camera for Surveys observations of the system also reveal a spiral-rich group of 10 galaxies within 40" of the elliptical…
Space Telescope Imaging Spectrograph Observations of Young Star Clusters in the Antennae Galaxies (NGC 4038/4039)
Gilmore, Diane; Blair, William P.; Leitherer, C. +6 more
Long-slit spectra of several dozen young star clusters have been obtained at three positions in the Antennae galaxies with the Space Telescope Imaging Spectrograph and its 52''×0.2" slit. Based on Hα emission-line measurements, the average cluster-to-cluster velocity dispersion in seven different cluster aggregates (``knots'') is <10…
Feedback and Brightest Cluster Galaxy Formation: ACS Observations of the Radio Galaxy TN J1338-1942 at z = 4.1
Ford, H. C.; Demarco, R.; Infante, L. +43 more
We present deep optical imaging of the z=4.1 radio galaxy TN J1338-1942, obtained using the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope, as well as ground-based near-infrared imaging data from the European Southern Observatory (ESO) Very Large Telescope (VLT). The radio galaxy is known to reside within a large galaxy over…
A Spectroscopic Analysis of Blue Stragglers, Horizontal Branch Stars, and Turnoff Stars in Four Globular Clusters
Saffer, Rex A.; De Marco, Orsola; Shara, Michael M. +4 more
We present a spectroscopic analysis of HST STIS and FOS low- and intermediate-resolution spectroscopy of 55 stars in four globular clusters (47 Tucanae, M3, NGC 6752, and NGC 6397). Stars hotter than Teff=5750 K and with a signal-to-noise ratio larger than 15 were analyzed with non-local thermodynamic equilibrium model atmospheres, and …
X-Ray Emission from Orion Nebula Cluster Stars with Circumstellar Disks and Jets
Bally, John; Feigelson, Eric D.; Kastner, Joel H. +5 more
We investigate the X-ray and near-infrared emission properties of a sample of pre-main-sequence (PMS) stellar systems in the Orion Nebula Cluster (ONC) that display evidence for circumstellar disks (``proplyds'') and optical jets in Hubble Space Telescope (HST) imaging. Our study uses X-ray data acquired during Chandra Orion Ultradeep Program (COU…
Initial results of high-latitude magnetopause and low-latitude flank flux transfer events from 3 years of Cluster observations
Russell, C. T.; Zhang, H.; Zong, Q. -G. +9 more
We present initial results from a statistical study of Cluster multispacecraft flux transfer event (FTE) observations at the high-latitude magnetopause and low-latitude flanks from February 2001 to June 2003. Cluster FTEs are observed at both the high-latitude magnetopause and low-latitude flanks for both southward and northward IMF. Among the 122…