The gaseous Halo of the Virgo Cluster Galaxy 45

Observations of the Virgo Cluster galaxy NGC 4569 in soft X-rays and in Hα reveal both an asymmetrically distributed hot gaseous halo and a giant filament of diffuse emission, respectively, extending from the same side of the disk, the latter one to at least 8.8 kpc. A deep longslit spectrum along the filament shows velocities systematically different from the systemic velocity of NGC 4569. With the inclination of the disk one can determine the Hα spur as a giant outflow in NGC 4569. This revised version was published online in August 2006 with corrections to the Cover Date.     

Tracing the star stream through M31 using planetary nebula kinematics

We present a possible orbit for the Southern Stream of stars in M31, which connects it to the Northern Spur. Support for this model comes from the dynamics of planetary nebulae (PNe) in the disc of M31: analysis of a new sample of 2611 PNe obtained using the Planetary Nebula Spectrograph reveals ∼20 objects with kinematics inconsistent with the normal components of the galaxy, but which lie at the right positions and velocities to connect the two photometric features via this orbit. The satellite galaxy M32 is coincident with the stream both in position and velocity, adding weight to the hypothesis that the stream comprises its tidal debris.     

Elektronenstrahl-Mikroanalyse des Meteoriten von Steinbach

Zusammenfassung Eine uns vom Naturhistorischen Museum in Wien freundlicherweise zur Verfügung gestellte Probe des Meteoriten von Steinbach wurde mit einem Elektronenstrahl-Mikroanalysator vom Typ CAMECA qualitativ und quantitativ auf die chemische Zusammensetzung der einzelnen Phasen untersucht.Besonders eingehend wurde dabei die Metallphase analysiert, da diese sich durch die Anwesenheit einer gut ausgebildeten Widmanstättenschen Struktur in Gegenwart von Tridymit als Druckindikator auszeichnet.Die nichtmetallischen Phasen wurden ebenfalls quantitativ bestimmt und ergeben leicht abweichende Ergebnisse von den Analysen vonN. Story-Maskelyne, O. Winkler undF. Heide. Interessant sind vor allem der relativ hohe Mangangehalt in Bronzit und Chromit sowie der Chromgehalt des Troilits.Die Anwendung der neuen Berechnungen über die Abkühlungsgeschichte der Meteoritenmutterkörper vonWood auf unsere quantitativen Analysen ergab eine Abkühlungsgeschwindigkeit von 10°/Million Jahre, was einem Mutterkörper von ca. 50–90 km Durchmesser und einem Zentraldruck von 200 b entspricht.

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Summary A sample of the meteorite of Steinbach, made available by the Naturhistorisches Museum at Vienna, has been analyzed qualitatively and quantitatively by a CAMECA electron-beam microanalyzer.Detailed examination has been made on the structure of the metal phase, as the presence of a well-grown Widmanstätten-structure in contact with trydimite as a pressure-indicator is a direct proof for the formation of the Widmanstätten-structure without pressure.The nonmetallic phases have been analyzed quantitatively and the results are slightly different from those ofStory-Maskelyne, Winkler andHeide. Very interesting is the relatively high content of manganese in bronzite and chromite, also the chromium content of troilite.The application of the new computations ofWood, dealing with the cooling history of meteorite-parentbodies to our quantitative analyses indicate a cooling rate of 10° C/Million years, according to a parentbody of appr. 50–90 km diameter and a central pressure of appr. 200 b.

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Mit 8 Textabbildungen

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Herrn Professor Dr.F. Machatschki zum 70. Geburtstag gewidmet.     

On the polarization and anisotropy of solar X-radiation during flares

Starting from the idea that the electrons accelerated during a solar flare have originally a preferred direction, the angular distribution and the polarization of bremsstrahlung below 10 Å is calculated taking into account the influence of the magnetic field. The energy distribution of the nonthermal electrons is based on X-ray spectra measured by the Leicester group during flares in 1962 and 1967. In addition to the case of a fixed angle between the electron velocity and the magnetic field, an angular distribution of the form sin ⁿ is considered. The results may be used to test flare models. Recent measurements of the polarization of solar X-radiation yield the expected order of magnitude.Paper presented to the Int. Symp. on Solar-Terr. Phys., Leningrad, May 1970.     

Partitioning of semi-soluble organic compounds between the water phase and oil droplets in produced water

When selecting produced water treatment technologies, one should focus on reducing the major contributors to the total environmental impact. These are dispersed oil and semi-soluble hydrocarbons, alkylated phenols, and added chemicals. Experiments with produced water have been performed offshore on the Statoil operated platforms Gullfaks C and Statfjord B. These experiments were designed to find how much of the environmentally relevant compounds were dissolved in the water phase and not associated to the dispersed oil in the produced water. Results show that the distribution between the dispersed oil and the water phase varies highly for the different components groups. For example the concentration of PAHs and the C6-C9 alkylated phenols is strongly correlated to the content of dispersed oil. Therefore, the technologies enhancing the removal of dispersed oil have a higher potential for reducing the environmental impact of the produced water than previously considered.     

A forced response to twentieth century climate conditions of two Spanish forests inferred from widths and stable isotopes of tree rings

This dendroclimatological research is based on two close pine forests (Pinus sylvestris and Pinus uncinata) located at the Northern Iberian System (Spain), and three tree-ring variables (ring widths, δ ¹³C and δ ¹⁸O). The climate-tree growth system was assessed at local and regional scales using three climate datasets. Calibration of tree-ring records with climate showed a diversity of information recorded in the different variables, such as a general response to temperature and precipitation of current growing period, and an important contribution of previous year conditions understood as the use of food reserves. The analysis of the stability of climate-tree growth relationships throughout the twentieth century showed a shift of those climatic variables to which trees responded and results suggested an enhancement of reserve use on current tree growth. The results obtained in this research made clear a physiological adaptation of trees to changing climate. The results provided hints that the recent warming coupled to slight precipitation decay are forcing growth of studied trees to a higher stress status and to a higher climate-growth synchronisation. These instabilities also have implications on future dendroclimatic reconstructions performed with trees growing under changing environments.     

Interdecadal modulation of the relationship between ENSO,IPO and precipitation: insights from tree rings in Australia

Australian climate-proxy reconstructions based on tree rings from tropical and subtropical forests have not been achieved so far due to the rarity of species producing anatomically distinct annual growth rings. Our study identifies the Australian Red Cedar (Toona ciliata) as one of the most promising tree species for tree-ring research in Australasia because this species exhibits distinct annual tree rings, a prerequisite for high quality tropical dendroclimatology. Based on these preliminary studies, we were able, for the first time in subtropical and tropical Australia, to develop a statistically robust, precisely dated and annually resolved chronology back to AD1854. We show that the variability in ring widths of T. ciliata is mainly dependent on annual precipitation. The developed proxy data series contains both high- and low-frequency climate signals which can be associated with the El Niño Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). A comparison of different data sets (Brisbane precipitation, tree rings, coral luminescence record from the Great Barrier Reef, ENSO and IPO) revealed non-stationary correlation patterns throughout the twentieth century but little instability between the new tree-ring chronology and Brisbane precipitation.     

Impact of prescribed Arctic sea ice thickness in simulations of the present and future climate

This paper describes atmospheric general circulation model climate change experiments in which the Arctic sea-ice thickness is either fixed to 3 m or somewhat more realistically parameterized in order to take into account essentially the spatial variability of Arctic sea-ice thickness, which is, to a first approximation, a function of ice type (perennial or seasonal). It is shown that, both at present and at the end of the twenty-first century (under the SRES-A1B greenhouse gas scenario), the impact of a variable sea-ice thickness compared to a uniform value is essentially limited to the cold seasons and the lower troposphere. However, because first-year ice is scarce in the Central Arctic today, but not under SRES-A1B conditions at the end of the twenty-first century, and because the impact of a sea-ice thickness reduction can be masked by changes of the open water fraction, the spatial and temporal patterns of the effect of sea-ice thinning on the atmosphere differ between the two periods considered. As a consequence, not only the climate simulated at a given period, but also the simulated Arctic climate change over the twenty-first century is affected by the way sea-ice thickness is prescribed.