Investigation of clusters of galaxies II. A two colour photometry for the cluster Abell 1795

Eine photographische Photometrie in B and V wurde für den cD-Haufen A 1795 durchgeführt. Dieser Haufen liegt in der Nähe des galaktischen Nordpols. Unser Katalog enthält 721 Galaxien in einem Gebiet von 1.6 ° um das Haufenzentrum.     

Observational evidence for the evolution of cD galaxies

We consider current problems connected with the formation of cD galaxies. The subject of this paper is to compare internal properties of cD galaxies such as radial colour distribution, envelope luminosity, and peculiar velocity with mass segregation effects in their parent clusters. This consideration is a forthcoming attempt to find commonly valid essential correlations between peculiarities of brightest cluster members and global cluster properties. We find tight correlations between the discussed properties and conclude that merger processes seem to play an important roll in the formation process of cD galaxies.     

Distribution of Galaxies in 10 Clusters

The number-density distributions for further 10 clusters of galaxies were derived by counting galaxies on the red Palomar Sky Survey prints. For 9 clusters the radial number-density distribution and the radial cumulative galaxy distribution were calculated.     

Zur Entwicklung von Galaxien unter Berücksichtigung von Stößen gasförmiger Wolken

BROSCHE'S investigations concerning the evolution of galaxies are repeated using values for the starting-point which deviate from that of BROSCHE. Especially, a protogalaxy is assumed to consist of gas clouds each of them having a mass of 10⁵ M⊙. The comparison of the results with observation is satisfactory. BROSCHE's interpretation of the HUBBLE sequence as a sequence depending on the angular momentum seems to be questionable.     

Water column monitoring near oil installations in the North Sea 2001-2004

Fisheries have been vital to coastal communities around the North Sea for centuries, but this semi-enclosed sea also receives large amounts of waste. It is therefore important to monitor and control inputs of contaminants into the North Sea. Inputs of effluents from offshore oil and gas production platforms (produced water) in the Norwegian sector have been monitored through an integrated chemical and biological effects programme since 2001. The programme has used caged Atlantic cod and blue mussels. PAH tissue residues in blue mussels and PAH bile metabolites in cod have confirmed exposure to effluents, but there was variation between years. Results for a range of biological effects methods reflected exposure gradients and indicated that exposure levels were low and caused minor environmental impact at the deployment locations. There is a need to develop methods that are sufficiently sensitive to components in produced water at levels found in marine ecosystems.     

Sedimentology of a Late Quaternary lacustrine record from the south-eastern Carpathian Basin

The Upper Pleistocene geoarchives in the south-eastern Carpathian Basin are represented predominantly by loess–palaeosol records. In 2015, a 10 m sediment core composed of clay-rich lacustrine sediments was recovered by vibracoring a dry lake basin located between the Vršac Mountains (Serbia) and the Banat Sands in the south-eastern Carpathian Basin; a location relevant for placing regional archaeological results in a palaeoenvironmental context. Here, we present results from geoelectrical prospection and a lithostratigraphic interpretation of this sequence supported by a detailed granulometric study supplemented by ostracod analysis. An age model based on luminescence dating is discussed against sedimentological proxy data and its implication for palaeoenvironmental change. The cores show a stratigraphy of lighter ochre-coloured and darker greyish sediment, related to the deposition of clay and silt trapped in an aquatic environment. Geophysical measurements show ~20 m thick lacustrine sediments. The grain-size distributions including the variability in fine clay are indicative of a lacustrine environment. Fine particles were brought into the depositional environments by aquatic input and settled from suspension; also, direct dust input is constrained by grain-size results. Riverine input and aeolian dust input interplayed at the locality.     

Accompanying seismic refraction investigations along the profile DEKORP 2-North

Seismic refraction measurements were carried out along the DEKORP 2-N reflection line. Traveltime data have been inverted to velocity-depth distributions using x-t-inversion- und ray-tracing-methods. The velocity-model shows alternating layers of high and low velocity. High-velocity values range from 6.0 to 6.6 km/s in the upper crust and from 70 to 8.2 km/s in the lower crust. In low-velocity zones velocities do not exceed 6.25 km/s. The crust/mantle boundary lies in about 28–30 km depth. Correlations exist between the velocity-model of refraction seismics and the line drawing section of reflection seismics.

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Zusammenfassung Entlang dem tiefenseismischen Reflexionsprofil DEKORP 2-Nord wurden seismische Refraktionsmessungen durchgeführt. Die Laufzeitdaten wurden mit Hilfe von x-t-Inversions- und Ray-Tracing-Verfahren in Geschwindigkeits-Tiefen-Verteilungen transformiert. Es treten alternierende Hoch- und Niedriggeschwindigkeitszonen auf. In der oberen Kruste treten hohe Geschwindigkeitswerte im Bereich von 6,0 bis 6,6 km/s auf und in der unteren Kruste Werte von 7,0 bis 8,2 km/s. Die Geschwindigkeitswerte in Niedriggeschwindigkeitszonen überschreiten 6,25 km/s nicht. Die Grenze zwischen Erdkruste und Erdmantel liegt in einer Tiefe von etwa 28 bis 30 km. Es bestehen Übereinstimmungen zwischen dem Geschwindigkeitsmodell der Refraktionsseismik und der Struktur der reflexionsseismischen Sektion.

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Résumé Des mesures en sismique-réfraction ont été effectuées le long du profil de sismique réflexion DEKORP 2-N. On a réalisé une inversion des temps de propagation en distribution vitesse/profondeur par les méthodes de l'inversion x-t et du traçage de raie. Le modèle des vitesses fait apparaître des couches alternées à grandes et faibles vitesses. Les grandes vitesses sont de 6,0 à 6,6 km/sec dans la croûte supérieure et de 7,0 à 8,2 km/sec dans la croûte inférieure. Dans les zones à faible vitesse, celle-ci n'excède pas 6,25 km/sec. La profondeur du contact croûte/manteau est d'environ 28 à 30 km. Il existe une correspondance entre le modèle des vitesses de la sismique-réfraction et l'image fournie par la sismique-réflexion.

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