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Solar observations from space and from the ground
Curdt, W.
Recent results from space missions like YOHKOH, SOHO or TRACE as well as ground-based observations clearly indicate that physical processes of most solar phenomena take place on small scales, which are still below the resolution of the instruments employed. There is an urgent need for observations at higher resolution and also for their extension …
Intercalibration of SUMER and CDS on SOHO. III. SUMER and CDS-GIS
Solanki, Sami K.; Schühle, Udo; Pauluhn, Anuschka +2 more
Simultaneous observation of the same solar sources with different instruments is one way to test prelaunch radiometric calibrations and to detect changes in responsivity with time of extreme-ultraviolet instruments in space. Here we present the results of intercalibration of the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrome…
Excitation of Solar p-mode Oscillations by Flares
Basu, Sarbani; Antia, H. M.; Ambastha, Ashok
Solar flares release large amounts of energy at different layers of the solar atmosphere. It is, therefore, expected that major flares would be able to excite waves, thereby affecting the p-mode oscillation characteristics. From the analysis of MDI data, we find that power in p-modes appears to increase for some flares, beyond the normal values ex…
Abell 851: Are we looking at the beginning of a merging process?
Schindler, S.; De Filippis, E.
We present an XMM observation of the moderately distant (z=0.41)galaxy cluster CL 0939+4713 (Abell 851), an exceptionally rich cluster. The formation and evolution of clusters depends sensitively on cosmological parameters like the mean matter density in the universe Οm. Therefore it is important to determine the dynamical state of clus…
On the importance of searching for oscillations of the Jovian inner radiation belt with a quasi-period of 40 minutes
Lou, Yu-Qing; Zheng, Chen
Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-min period (QP-40) from the south polar direction of Jupiter in 1992 February. Such polar QP-40 burst activities were found to correlate well with arrivals of high-speed solar winds at Jupiter. We advance the physica…
Testing SPI imaging of high-energy and extended sources
Strong, A. W.; Wunderer, C. B.; Connell, P. +2 more
INTEGRAL's main instruments employ coded apertures to obtain directional information on the incoming radiation. In order to experimentally better determine the imaging capabilities of the spectrometer SPI, the SPI Imaging Test Setup (SPITS) has been built at MPE. It consists of the SPI coded mask and two SPI-identical Ge detectors on an XY-table w…
XMM-Newton high-resolution x-ray spectroscopy of the Wolf-Rayet object WR25 (WN6HA+04F)
Schmutz, W.; Raassen, A. J. J.; Mewe, R. +5 more
We report the analysis of the X-ray spectrum of the Wolf-Rayet star WR 25, observed by RGS and EPIC-MOS on board XMM-Newton. Temperatures up to 40 MK have been determined. Strong absorption, exceeding the value due to the Inter Stellar Medium (ISM) has been detected and assigned to the dense stellar wind.
The system of the Milky Way, LMC and SMC
Ružčka, Adam
A simple sticky-particle numerical model has been developed in order to check whether extended structures of gas created due to the dynamical evolution of the Galaxy and the Magellanic Clouds system can be explained as remnants of a tidal interaction. Influence of dissipative nature of gaseous medium has been taken into account. The most remarkabl…
X-ray emission from dwarf galaxies: IC 2574 revisited
Walter, Fabian; Brinks, Elias; Kerp, Jürgen
Until recently, few unequivocal detections had been reported of the hot, X-ray emitting gas thought to be associated with the large, coherent structures variously described as supershells or superbubbles in dwarf irregular (dIrr) galaxies. In this contribution we report follow-up XMM-Newton and Chandra observations of our ROSAT detection of X-ray …
The Mass/Eccentricity Limit in Double Star Astronomy
Dommanget, J.
A research that we conducted in 1963 on the evolution of the binaries based on the available orbital data to obtain a philosophical degree, led to the establishment of an interesting and new diagram between the logarithm of the total mass and a particular parameterX, bound to the areal constant. This appeared to have a real physical significance b…