The starburst in the Wolf-Rayet nucleus of the Liner NGC 6764

We present high resolution millimeter, near-infrared, and optical data on the Wolf-Rayet nucleus of the Liner NGC 6764. The millimeter¹²CO(1-0) maps were obtained using the Nobeyama Millimeter Interferometer. Near-infrared images in the K-band continuum and the 2.12µm H₂, 2.06µm He I, 2.17µm Br, and 1.64µm [Fe II] lines were taken with the MPE imaging spectrometer FAST at the William Herschel Telescope on La Palma, Spain. The optical data were obtained at the 3.5m telescope on Calar Alto, Spain. The measurements indicate a strong concentration of molecular gas and a massive starburst at the nucleus of NGC 6764. The interferometric position velocity map of the nucleus shows the presence of distinct molecular cloud complexes with an apparently asymmetric velocity field shifted towards the blue with respect to the systemic velocity of 2420 km s^–1. The distribution of the 2.12µm H₂ line flux exhibits extensions approximately perpendicular to the bar which are in agreement with structural features in VLA radio maps and IRAM 30m maps of the¹²CO(2–1) line emission. This may represent evidence for combination of a nuclear outflow and a central oval distortion of gas predicted by gas dynamical calculations as a response to a bar like potential. A detailed investigation of the Wolf-Rayet-feature at 466 nm indicates that it is spatially extended on a scale of a few arcseconds.     

I Zwicky 1: Decomposition and dynamics of the nearby QSO host

We address current theories of research on morphology, environment and evolution of active galaxies in the form of a detailed case study of the nearby QSO host I Zw 1. This study is based on sub-kpc resolution ¹²CO(1-0) observations with the BIMA mm-interferometer and on near-infrared imaging with ISAAC at the VLT. The ¹²CO(1-0) maps reveal a circumnuclear molecular gas ring with a radius of 0.9 kpc. The imaging data in the J-band are analyzed with respect to a disk-bulge decomposition. Together with a model of the gas rotation curve, the radial profile of the dynamical J-band mass-to-light ratio (M/L) is discussed. The J-band images give new evidence for an interaction between I Zw 1 and its nearby companion. First results from a sequence of N-body simulations for an extensive test of the parameter space of the interaction are presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sharp images of young stellar objects

We present high resolution infrared images of the pre-main sequence star V536 Aql and polarization maps of the reflection nebula IRN Cha observed with the SHARP camera on the ESO NTT. Extended structures are observed near V536 Aql. The polarization pattern of IRN Cha is typical of a centrally illuminated source but with a central band of anomalously oriented polarization believed to occur in an optically thick disk.     

The influence of suspended cohesive sediments on boundary-layer structure and erosive activity of turbulent seawater flow

Velocity and suspension measurements in the logarithmic layer of hydraulically smooth turbulent tidal flow from the North Sea are reported. The data were not compatible with the assumption of Newtonian flow for the experimental seawater—clay suspension.Laboratory measurements were initiated with mud and seawater from the North Sea in which the boundary-layer structure of this two-phase flow was measured down into the viscous sublayer. The dilute seawater—clay suspension was a mixture of illite, kaolinite and chlorite minerals with concentrations less than 380 mg/l and exhibited turbulent drag reduction.By reviewing flow measurements of other authors it is suggested that turbulent drag reduction occurs on a geophysical scale if the flows transport cohesive sediments. It is proposed that drag reduction is caused by dynamic interaction between turbulent shear strain in the flow and deformation of aggregates.As a consequence, the values of the critical friction velocity $\text{u}{}_{\mathrm{<mtext>1\; </mtext><mtext>crit</mtext>}}$ and of erosion rates must be reviewed for cohesive bottom materials. Normally they were obtained under the assumption of a Newtonian flow structure which is not applicable if the flow transports cohesive sediments.To detect the occurrence of drag reduction in geophysical boundary layers (hydraulically smooth), flow measurements must be performed down into the viscous sublayer. The adequate velocity sensors must have a diameter of ?1 mm.     

Impact structures and events - a Nordic perspective

Impact cratering is one of the fundamental processes in the formation of the Earth and our planetary system, as reflected, for example in the surfaces of Mars and the Moon. The Earth has been covered by a comparable number of impact scars, but due to active geological processes, weathering, sea floor spreading etc, the number of preserved and recognized impact craters on the Earth are limited. The study of impact structures is consequently of great importance in our understanding of the formation of the Earth and the planets, and one way we directly, on the Earth, can study planetary geology.
The Nordic-Baltic area have about thirty confirmed impact structures which makes it one of the most densely crater-populated terrains on Earth. The high density of identified craters is due to the level of research activity, coupled with a deterministic view of what we look for. In spite of these results, many Nordic structures are poorly understood due to the lack of 3D-geophysical interpretations, isotopeor other dating efforts and better knowledge of the amount of erosion and subsequent tectonic modifications.
The Nordic and Baltic impact community is closely collaborating in several impact-related projects and the many researchers （about forty） and PhD students （some seventeen） promise that this level will continue for many more years. The main topics of research include geological, geophysical and geochemical studies in combination with modeling and impact experiments. Moreover, the Nordic and Baltic crust contains some hundred suspect structures which call for detailed analysis to define their origin.
New advanced methods of analyzing geophysical information in combination with detailed geochemical analyses and numerical modeling will be the future basic occupation of the impact scientists of the region. The unique Cretaceous/Tertiary boundary （K-T） occurrences in Denmark form an important source of information in explaining one of the major mass extinctions on Earth.     

NIR/Optical Interferometry

E01 VLTI‐PRIMA Fringe Tracking Testbed E02 The Fringe and Flexure Tracking System for the LBT interferometric camera LINC‐NIRVANA E03 GRAVITY: The AO assisted, two object beam combiner instrument for the VLTI E04 (Re)Solving the dynamic atmospheres of carbon‐rich giants E05 Do's and Don'ts of MIDI Data‐reduction E06 Bispectrum speckle imaging of the ultracompact HII region K3‐50A E07 Differential astrometry and astrometric planet searches with the VLTI E08 First AU‐scale observations of V1647 Ori: The outbursting young star in the McNeil's Nebula E09 Mid‐infrared imaging at the VLTI: An APreS‐MIDI image reconstruction study E10 VLTI/MIDI observation of the silicate carbon star Hen 38 (IRAS08002‐3803): Silicate dust reservoir spatially resolved for the first time E11 Mid‐infrared spectro‐interferometric observation of the Mira variable RR Sco with the VLTI/MIDI instrument E12 Scientific Prospects for VLTI in the Galactic Centre: Getting to the Schwarzschild Radius E13 VLTI near‐infrared observations of the stellar multiple system δ Velorum E14 The first VLTI observations of the Galactic Center E15 Bispectrum speckle interferometry of the massive protostellar outflow source IRAS 23151+5912 E16 Interferometric Observations of Infrared Companions with MIDI E17 Evolution and radial distribution of dust in the inner 1‐10A.U. of circumstellar disks around low‐mass young stellar objects. E18 Near‐infrared Interferometry with the AMBER Instrument of the VLTI E19 APreS‐MIDI ‐ Interferometic Imaging in the Mid‐Infrared E20 Mining the sky: Selection of extragalactic targets for interferometric observations