IR-Zyklotronspektroskopie akkretierender magnetischer weisser Zwerge Abschlussbericht

SIGLEAvailable from TIB Hannover: DtF QN1(85,44) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Bonn (Germany)DEGerman

ROSAT, HST und optische Untersuchungen an nichtmagnetischen kataklysmischen Veraenderlichen und superweichen Roentgenquellen Abschlussbericht

In this project, a new type of cosmic sources of soft X-ray emission has been analysed in detail based on observations obtained with the ROSAT X-ray satellite, the Hubble Space Telescope (HST), and large ground-based optical telescopes. The scientific problems addressed in this project lie in the field of astrophyisical high-temperature plasms and include compact stars (white dwarfs), nuclear fusion processes, and radiation transport of high-energy emissions. Significant progress was obtained with the analysis of the properties of accreting white dwarfs, the X-ray emission from the boundary layer between accretion disk and white dwarf, and the nature of supersoft X-ray binaries. (orig.)SIGLEAvailable from TIB Hannover: DtF QN1(83,3) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany); DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Bonn (Germany)DEGerman

Nutzung von ROSAT und HST zur Diagnostik von Akkretionsplasmen auf magnetischen weissen Zwergen Abschlussbericht

In this project, the ROSAT satellite, the Hubble-Space-Telescope (HST), and large ground-based telescopes have been used for a detailed analysis of magnetic compact stars (white dwarfs) which appear as bright sources of soft X-ray emission. The scientific problems addressed in this project lie in the field of astrophysical high-temperature plasms and include the origin of high-energy radiation, the radiation transport, and the secular evolution of close binary stars. Based on the optical identification of new bright soft X-ray sources from the ROSAT All-Sky Survey the number of known such systems could be significantly increased and allowed us for the first time to obtain insight into the general properties of these systems. (orig.)SIGLEAvailable from TIB Hannover: DtF QN1(83,2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany); DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Bonn (Germany)DEGerman

RX J1313.2-3259, a long-period Polar discovered with ROSAT

We report observations of a new AM Herculis binary identified as the optical counterpart of the X-ray source RX J1313.2-3259, detected during the ROSAT All-Sky Survey (RASS). It has an orbital period of 251 min and is strongly modulated at optical wavelengths. The long-term behavior is characterized by a pronounced variation in X-rays between the RASS and two subsequent pointings (decrease by a factor 40 in count rate) and by moderate changes in the optical brightness (up to a factor 5). The X-ray spectrum is dominated by a soft quasi-blackbody component, with a smaller contribution from thermal bremsstrahlung. Measurements of high circular polarization confirm its classification as a Polar with a magnetic field strength of 56 MG. The average visual magnitude of RX J1313.2-3259 is V#approx =#16"m, for its distance we get #approx =#200 pc. (orig.)SIGLEAvailable from TIB Hannover: RR 7310(99-50) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Accretion and magnetism - AM Herculies stars. Polars in the ROSAT era

The accretion processes in Am Herculis binaries are reigned by the strong magnetic field of a mass-accreting white dwarf. In the first part of this article I describe the methods applicable to infer the strength and structure of the magnetic fields in these systems. These are based on direct measurements of Zeeman split Balmer lines and/or harmonic cyclotron emission. All well-studied systems show signs of complex field structures or at least deviations from the most simple model of a centered dipole. The observed range of B-values is 10 -70 MG. The evolution of the systems is responsible for this range being much narrower than that measured in single white dwarfs, 100 kG - 1000 MG (see Schmidt 1995, this volume). The following parts of this article are devoted to other processes intimately interwoven with the presence of magnetic fields. These are the accretion streams (instead of accretion disks), the different ways of energy release in the accretion spots and the synchronous rotation of both stars. Considerable progress was reached in various fields after the launch of ROSAT which detected a lot of new and some very remarkable systems and which made detailed observational studies of individual systems possible. (orig.)Available from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

New bright soft X-ray selected ROSAT AGN. Pt. 2 Optical emission line properties

We present the emission line properties of a sample of 76 bright soft X-ray selected ROSAT Active Galactic Nuclei. All optical counterparts are Seyfert 1 galaxies with rather narrow permitted lines, strong optical FeII line blends, and weak forbidden lines. By selection, they also have steep soft X-ray spectra when compared with typical Seyfert 1 galaxies. We discuss possible origins of these peculiar trends employing detailed correlation analyses, including a Principal Component Analysis. The optical spectra are presented in the AppendixAvailable from TIB Hannover: RN 9303(474) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

New bright soft X-ray selected ROSAT AGN II. Optical emission line properties

SIGLEAvailable from: www.mpa-garching.mpg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Structural studies of emission regions in polars

We report on structure in the emissions region encountered in polars. This will become a travel along the accretion stream, starting at the surface of the secondary star, moving along the horizontal and vertical parts of the stream and finishing in the accretion spots on the white dwarf. For the first time we establish a detailed picture of the origin of atomic emission lines in a polar by means of Doppler tomography. (orig.)Available from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Identification of soft high galactic latitude RASS X-ray sources. Pt. 2 Sources with PSPC count rate CR<0.5 cts/s

SIGLEAvailable from TIB Hannover: RR 7310(99-20) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman