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Oxygen Abundances in the Milky Way Using X-Ray Absorption Measurements toward Galaxy Clusters
Mushotzky, R. F.; Baumgartner, W. H.
We present measurements of the oxygen abundance of the Milky Way's ISM by observing the K-shell X-ray photoionization edge toward galaxy clusters. This effect is most easily observed toward objects with Galactic columns (nH) of a few times 1021 cm-2. We measure X-ray column densities toward 11 clusters and find tha…
Evidence for colliding winds in WR 25 from XMM-Newton observations of X-ray variability
Corcoran, M. F.; Pollock, A. M. T.
The Wolf-Rayet star WR 25 in the Carina Nebula is a surprisingly bright X-ray source, and amongst the brightest WR stars in X-rays. It is a suspected binary star, though its binary nature has been a matter of controversy. We report here observations of WR 25 from the XMM-Newton archive which showed an increase in X-ray luminosity of more than a fa…
Coronal Emission Measures and Abundances for Moderately Active K Dwarfs Observed by Chandra
Wood, Brian E.; Linsky, Jeffrey L.
We have used Chandra to resolve the nearby 70 Oph (K0 V+K5 V) and 36 Oph (K1 V+K1 V) binary systems for the first time in X-rays. The LETG/HRC-S spectra of all four of these stars are presented and compared with an archival LETG spectrum of another moderately active K dwarf, ɛ Eri. Coronal densities are estimated from O VII line ratios and emissio…
Venus before Venus Express
Taylor, Fredric W.
An overview is given of current knowledge and mysteries about the planet Venus, with emphasis on those aspects that are intended to be studied with the Venus Express mission following orbit insertion at the planet in March 2006.
Chemical Enrichment of the Complex Hot ISM of the Antennae Galaxies. II. Physical Properties of the Hot Gas and Supernova Feedback
Zezas, A.; Raymond, J. C.; King, A. R. +5 more
We investigate the physical properties of the interstellar medium (ISM) in the merging pair of galaxies known as the Antennae (NGC 4038/4039), using the deep co-added ~411 ks Chandra ACIS-S data set. The method of analysis and some of the main results from the spectral analysis, such as metal abundances and their variations from ~0.2 to ~20-30 tim…
The Magnetic Field Strength in the Wall of the Local Bubble toward l, b ~ 300°, 0°
Andersson, B. -G.; Potter, S. B.
We present polarization measurements in the region around l, b = 300°, 0°, toward stars with well-determined distances, primarily in the range 40-200 pc. We argue that these observations trace polarization caused by dust in the wall of the Local Bubble (LB). Using a Chandrasekhar-Fermi analysis, we derive a plane-of-the-sky magnetic field strength…
Chandra and Hubble Space Telescope Study of the Globular Cluster NGC 288
Anderson, Scott F.; Kong, Albert K. H.; Verbunt, Frank +5 more
We report on the Chandra X-Ray Observatory observations of the globular cluster NGC 288. We detect four X-ray sources within the core radius and seven additional sources within the half-mass radius down to a limiting luminosity of LX=7×1030 ergs s-1 (assuming cluster membership) in the 0.3-7 keV band. We also obser…
Can the unresolved X-ray background be explained by the emission from the optically-detected faint galaxies of the GOODS project?
Lehmer, B. D.; Alexander, D. M.; Bauer, F. E. +3 more
The emission from individual X-ray sources in the Chandra Deep Fields and XMM-Newton Lockman Hole shows that almost half of the hard X-ray background above 6keV is unresolved and implies the existence of a missing population of heavily obscured active galactic nuclei (AGN). We have stacked the 0.5-8keV X-ray emission from optical sources in the Gr…
Observations of Flux Rope Formation in the Outer Corona
Sheeley, N. R., Jr.; Wang, Y. -M.
In previous studies employing the Large Angle and Spectrometric Coronagraph (LASCO), we identified a class of white-light ejections that separate into incoming and outgoing components at distances of ~3-5 Rsolar from Sun center. These events, of which up to several per month are observed during high solar activity, are generally precede…
Exploring the lower mass function in the young open cluster IC 4665
James, D. J.; Testi, L.; Palla, F. +8 more
We present a study of the young (30-100 Myr) open cluster IC 4665 with the aim to determine the shape of the mass function well into the brown dwarf regime. We photometrically select 691 low-mass stellar and 94 brown dwarf candidate members over an area of 3.82 square degrees centred on the cluster. K-band follow-up photometry and Two-Micron All-S…