Conclusion To summarize, the readout and the control system of the CCD mosaic camera are running since December 1991 at the La Silla Observatory (ESO). The overall performance of the camera has been good. About 12000 pictures (data and flat-fields) have been successfully registered up to now. We will report in the near future preliminary scientific results of the EROS experiment. 相似文献
Water suppliers face major challenges such as climate change and population growth. To prepare for the future, detailed knowledge of water resources is needed. In southern Germany, the state water supplier Zweckverband Landeswasserversorgung provides 3 million people with drinking water obtained from a complex karst and alluvial aquifer system and the river Danube. In this study, a combination of different tracing techniques was used with the goal of a multi-scale characterization of the aquifer system and to gain additional knowledge about groundwater flow toward the extraction wells in the Danube Valley. For the small-scale characterization, selected groundwater monitoring wells were examined using single-borehole dilution tests. With these tests, a wide range of flow behavior could be documented, including fast outflow within just a few hours in wells with good connection to the aquifer, but also durations of many weeks in low-permeability formations. Vertical flow, caused by multiple flow horizons or uprising groundwater, was detected in 40% of the tested wells. A regional multi-tracer test with three injections was used to investigate the aquifer on a large scale. For the highly karstified connection between a swallow hole and a spring group, high flow velocities of around 80 m/h could be documented. Exceptionally delayed arrivals, 250 and 307 days after the injection, respectively showing maximum velocities of 0.44 and 0.39 m/h, were observed in an area where low-permeability sediments overlay the karst conduits. With the chosen methods, a distinct heterogeneity caused by the geological setting could be documented on both scales.
Doppler images are presented for the RS CVn-type binary ζ And. Our upgraded Doppler imaging code TempMapε takes into account the distorted geometry of the primary giant component. On the maps several low latitude spots are restored with a temperature contrast of about 1000 K. Some weak polar features are also found. Cross-correlation of the consecutive Doppler-maps suggests solar-like differential surface rotation. 相似文献
The four main scientific objectives of PRIMA – the Phase-Referenced Imaging and Micro-arc second Astrometry facility for the
VLTI – will be described:– extra-solar system characterization with astrometry, to detect planets and evaluate their mass,
and imaging of the dust accretion disk,– galactic center study with astrometry(dynamics of the bulge stars) and imaging at
10μm (piercing the gas and dust clouds surrounding the galactic center),– observations of AGNs and other extra-galactic objects,
too faint to be observed without PRIMA, for which partial imaging is needed to constrain their structuremodels,– micro-gravitational
lensing event resolution (imaging and astrometry of their photo-center) in the Galactic Bulge and Magellanic Clouds, helping
to determine directly the lens mass and distance.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
A thin gaseous disk with a nearly Keplerian rotation profile and free boundaries in the external gravitational field of a
point gravitating object does not generate any growing perturbation eigenmodes. In spite of this, a significant transient
growth of linear perturbations measured by the evolution of their total acoustic energy is possible in such a disk. This is
shown within the framework of the simplest model of an inviscid polytropic thin disk with a finite radial extent in which
small adiabatic perturbations that are a linear combination of neutral eigenmodes with a corotation radius beyond the outer
flow boundary are considered. 相似文献