Search Publications
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…
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 …
A survey searching for the epoch of assembling of Hubble types
Pasquali, Anna; de Mello, DuÍlia F.
We have started a survey of galaxies at intermediate redshifts using the HST-STIS parallel fields. Our main goal is to analyse the morphology of faint galaxies in order to estimate the epoch of formation of the Hubble classification sequence. The high resolution of STIS images (0.05″) is ideal for this work and enables us to perform a morphologica…
UV Piscium and the Radiative Flux Scale
Vivekananda Rao, P.; Radhika, P.
Studies of eclipsing binaries with Hipparcos parallaxes are found to define a radiative flux relation for main sequence stars in the spectral range from B6 – F0which is about as well as to the stars derived from angular diameters. At lower temperatures the fluxes of the components fall below this curve which is caused due to the large intrinsic va…
Effect of Flow-Tube Geometry on Solar Wind Properties
Chen, Y.; Hu, Y. Q.
A mathematical description of the solar wind flow-tube geometry is proposed. The expansion factor of the flow tube f(r) (=a/r2, r is the heliocentric distance and a is the flow-tube cross-section area)increases monotonically from 1 at the coronal base to m at rc, and approaches its asymptotic value f∞ ne…
HST Observations of Sakurai's Object (V4334 Sgr) and Related Stars
Bond, Howard E.; Pollacco, Don L.
We describe our ongoing program of HST observations of Sakurai's Object(V4334 Sgr). Direct WFPC2 imaging from August 1996 through August 2000 revealsno transient features (such as light echoes), and documents the decline of thestar to below 24th visual magnitude in 2000. The surrounding planetary nebulahas shown no changes from 1996 through 2000. …
Transition region and coronal plasmas: instrumentation and spectral analysis
Dammasch, Ingolf E.; Wilhelm, Klaus; Hassler, Donald M.
The plasma conditions in the solar atmosphere and, in particular, in coronal holes are summarized, before space-borne instrumentation for observing these regions in vacuum-ultraviolet light is briefly introduced with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO) as exa…
SOHO, Yohkoh, Ulysses and Trace: The four solar missions in perspective, and available resources
Domingo, V.
Four solar observing spacecraft, now in operation, have obtained and continue to obtain data during the late phase of solar cycle 22 and hopefully most of cycle 23. The data are available for scientific analysis, practically in an unrestricted manner. A large pool of software suited for the processing and to help programming any data analysis is f…
Systematic Errors of High–Precision Photometric Catalogues
Mironov, Aleksey; Zakharov, Andrey
A very accurate imitation of Hipparcos and Tycho Hp, BT, andVT magnitudes was made using W, B, V, R magnitudes from the Tien Shan photometric catalogue. The calculated magnitudes were compared to the observed ones. It is shown that there are systematic differences between calculated and observed magnitudes. The systematic err…