Search Publications
Climate evolution of Venus
Taylor, F.; Grinspoon, D.
The processes in the atmosphere, interior, surface, and near-space environment that together maintain the climate on Venus are examined from the specific point of view of the advances that are possible with new data from Venus Express and improved evolutionary climate models. Particular difficulties, opportunities, and prospects for the next gener…
Resolving the Discrepancy Between Lensing and X-Ray Mass Estimates of the Complex Galaxy Cluster Abell 1689
Dahle, H.; Pedersen, K.; Limousin, M. +3 more
There is a long-standing discrepancy between galaxy cluster masses determined from X-ray and gravitational lensing observations of which Abell 1689 is a well studied example. In this work, we take advantage of 180 ks of Chandra X-ray observations and a new weak gravitational study based on a Hubble Space Telescope mosaic covering the central 1.8 M…
Unveiling the High Energy Tail of 1E 1740.7-2942 With INTEGRAL
Bouchet, L.; Bazzano, A.; Jourdain, E. +3 more
The microquasar 1E 1740.7-2942 is observed with INTEGRAL since Spring 2003. Here, we report on the source high-energy behavior by using the first three years of data collected with SPI and IBIS telescopes, taking advantage of the instruments complementarity. Light curves analysis showed two main states for 1E 1740.7-2942: the canonical low/hard st…
The Jet of 3C 17 and the Use of Jet Curvature as a Diagnostic of the X-ray Emission Process
Macchetto, F. D.; Capetti, A.; Grandi, P. +5 more
We report on the X-ray emission from the radio jet of 3C 17 from Chandra observations and compare the X-ray emission with radio maps from the VLA archive and with the optical-IR archival images from the Hubble Space Telescope. X-ray detections of two knots in the 3C 17 jet are found and both of these features have optical counterparts. We derive t…
Direct Imaging of Fine Structure in the Chromosphere of a Sunspot Umbra
Lites, B. W.; McIntosh, S. W.; de Wijn, A. G. +2 more
High-resolution imaging observations from the Hinode spacecraft in the Ca II H line are employed to study the dynamics of the chromosphere above a sunspot. We find that umbral flashes and other brightenings produced by the oscillation are extremely rich in fine structure, even beyond the resolving limit of our observations (0farcs22). The umbra is…
Chandra Observations of the Hybrid Morphology Radio Sources 3C 433 and 4C 65.15: FR IIs with Asymmetric Environments
Brandt, W. N.; Miller, B. P.
We present Chandra observations of the hybrid morphology radio sources 3C 433 and 4C 65.15, two members of the rare class of objects possessing an FR I jet on one side of the core and an FR II lobe on the other. The X-ray spectrum of 3C 433 shows intrinsic absorption (with a column density of N H sime 8 × 1022 cm-2…
The Circumstellar Medium of Cassiopeia a Inferred from the Outer Ejecta Knot Properties
Hwang, Una; Laming, J. Martin
We investigate the effect of the circumstellar medium density profile on the X-ray emission from outer ejecta knots in the Cassiopeia A supernova remnant using the 1 Ms Chandra observation. The spectra of a number of radial series of ejecta knots at various positions around the remnant are analyzed using techniques similar to those devised in prev…
Solar wind and substorm excitation of the wavy current sheet
Dandouras, I.; Lucek, E.; Fazakerley, A. N. +5 more
Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the Z…
Broad-band properties of the hard X-ray cataclysmic variables IGR J00234+6141 and 1RXS J213344.1+510725
Mukai, K.; de Martino, D.; Terada, Y. +5 more
Context: A significant number of cataclysmic variables have been detected as hard X-ray sources in the INTEGRAL survey, most of them of the magnetic intermediate polar type.
Aims: We present a detailed X-ray broad-band study of two new sources, IGR J00234+6141 and 1RXS J213344.1+510725, that allow us to classify them as secure members of the i…
Solar transition region above sunspots
Marsch, E.; Curdt, W.; Teriaca, L. +2 more
Aims: We study the transition region (TR) properties above sunspots and the surrounding plage regions, by analyzing several sunspot reference spectra obtained by the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument in March 1999 and November 2006.
Methods: We compare the SUMER spectra observed in the umbra, penumbra, plag…