Labor- und Inflight Kalibrierung von Space Experimenten zur Messung des Sonnenspektrums von 180 bis 3500 nm in internationaler Zusammenarbeit Abschlussbericht

Available from TIB Hannover: DtF QN1(61,27) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Entwurf, Bau und Installation von zwei Focal-Reduktor-Spectrographen fuer das Very Large Telescope (VLT) des European Southern Observatory (ESO) Schlussbericht

SIGLEAvailable from TIB Hannover: DtF QN1(50,36) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Wiederflug ORFEUS SPAS, Ueberarbeitung des ORFEUS-Echelle-Spektrographen Schlussbericht

Available from TIB Hannover: DtF QN1(80,3) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

Relativistic dissipative hydrodynamics in the 3+1 formulation

The equations governing dissipative relativistic hydrodynamics are formulated within the 3+1 approach. Dissipation is accounted for by applying the theory of extended causal thermodynamics (Israel-Stewart theory). This description eliminates the causality violating infinite signal speeds present in the conventional Navier-Stokes equation. (orig.)SIGLEAvailable from TIB Hannover: RR 1606(98-34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Spiral pattern in the optical polarization of NGC 6946

Wide-field images of NGC 6946 in linear optical polarization are presented. In large parts of the galaxy the polarization pattern delineates a spiral structure, in partial agreement with the radio polarization data. A possible explanation of such a pattern is the alignment of elongated dust grains in the regular interstellar magnetic field. The optical degree of polarization anti-correlates with the stellar density: the bright parts of the spiral arms and the nuclear region reveal the lowest degrees of polarization (below 0.5%), while the outer, less active regions are significantly polarized (up to 5%). This trend is similar as in the degree of polarization of radio synchrotron emission. This behavior could be interpreted as field tangling in star-forming regions. The higher resolution of our optical data would then allow to determine a new upper limit of the turbulence scale of #approx =#120 pc. In the southern and southwestern parts of NGC 6946 the polarization angles deviate from a spiral structure, indicating the exceptional character of these regions as known from observations in other frequency bands. However, we cannot exclude that here the optical polarization structure is influenced by effects external to the galaxy. The southern region of strong optical polarization and constant vector orientation might be interpreted as enhanced foreground polarization in a Galactic gas/dust cloud. (orig.)Available from TIB Hannover: RR 7310(98-06) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

3+1 formulation of non-ideal hydrodynamics

The equations governing dissipative relativistic hydrodynamics are formulated within the 3+1 approach for arbitrary spacetimes. Dissipation is accounted for by applying theory of extended causal thermodynamics (Israel-Stewart theory). This description eliminates the causality violating infinite signal speeds present in the conventional Navier-Stokes equation. As an example we treat the astrophysically relevant case of stationary and axisymmetric spacetimes, including the Kerr metric. The equations take a simpler form whenever the inertia due to the dissipative contribution can be neglected. (orig.)SIGLEAvailable from TIB Hannover: RR 1606(97-41) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Galactic magnetic fields and spiral arms. 3D dynamo simulations. Angular momentum transport by magnetic shear instability in protostellar disks

We investigate the evolution of three-dimensional (3D), large-scale galactic magnetic fields under the influence of time dependent gas flows in spiral arms and excited by a turbulent dynamo. Our principal goal is to check how the enhanced turbulent diffusion in spiral arms affects the global magnetic field structure evolving under the influence of the dynamically changing gaseous spiral arms. Self-consistent N-body simulations of a two-component, self-gravitating disk provide the time-dependent gas velocity, which is used as the large scale velocity field in the induction equation in addition to the turbulent electromotive force. Using the beam-smoothed polarization models the results of our simulations are confronted with observed configurations of polarization B-vectors in nearby galaxies. The magnetic field is found to be directly influenced by large-scale non-axisymmetric flow yielding the magnetic field locally well-aligned with gaseous spiral arms. Large pitch angles, similar to those of gaseous arms are found to propagate into the interarm region, too. However, in our models a decrease of magnetic pitch angles still occurs in the interarm region. It may be due to a diffusion coefficient between spiral arms too low to counteract the outward gas flows in these regions trying to turn the magnetic vectors to pitch angles of an opposite sign. A too weak #alpha# effect is also possible, probably because of a lack of extended diffusive halo at this stage of our model. (orig.)SIGLEAvailable from TIB Hannover: RR 7310(2000-09/10) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

A study of the Chamaelon star forming region from the ROSAT all-sky survey. Pt. 1 X-ray observations and optical identifications

We present the observations of the ROSAT all-sky survey (RASS) in the direction of the Chamaeleon cloud complex, as well as the spectroscopic identification of detected X-ray sources. The main purpose of this identification program was the search for low mass pre-main sequence stars. Sixteen previously known PMS stars were detected with high confidence by ROSAT. Eight are classical T Tauri stars and eight are weak-line T Tauri stars, Seventy-seven new weak-line T Tauri stars were identified on the basis of the presence of strong Li #lambda#6707 absorption, spectral type later than F0 and chromospheric emission. We give coordinates and count rates of the X-ray sources, and present optical spectra and finding charts for the sources identified optically as new pre-main sequence stars. Optical UBV (RI)_c and near-infrared JHKLM photometry for this sample of stars is also provided. In addition, 6 new dKe-dMe candidates are found among the RASS sources. (orig.)Available from TIB Hannover: RN 9303(319) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

EXOSAT observations of X-rays from classical novae during outburst stage

Submitted to Astronomy and Astrophysics, August, 1986SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

X-ray and optical study of the giant radio quasar 4C + 74.26

We present the optical and X-ray study of the radio-loud quasar 4C +74.26. The ASCA spectrum is rather complex with indications of a reflection component, a neutral iron line and a warm absorber. The underlying power law has a photon index of #GAMMA#=2.03#+-#0.09. The soft X-ray flux in 1996 is nearly twice as high as that found in a ROSAT observation in 1993 without apparent spectral changes. The X-ray data support the picture deduced from previous radio observations that 4C +74.26 is seen under a relative large angle (#propor to#45 ) with respect to its jet axis. However, the rather unusual X-ray spectral properties might as well be a signature of the quasar's young evolutionary status. No interaction between the quasar and the nearby #propor to#19 mag galaxy could be found in the optical images. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman