Local Stars as Tracers of Galactic Evolution

We describe the overall properties of a new catalogue of metallicities, ages, and galactic orbits for a large, complete sample of F and G dwarfs in the solar neighbourhood. Based on a magnitude-limited sample of ∼ 14000 stars, it is volume-complete to ∼ 40 pc. Together with the astrophysical parameters of direct relevance to models of the evolution of the disk, it will contain the basic photometric, astrometric, and radial velocity data from which they are derived. Information on duplicity is also included. The full exploitation of the data will require a lengthy analysis, in particular to assess the degree of completeness of subsamples of stars of different population types. An early result on the effects of diffusion of galactic orbits in the disk – essential for understanding the scatter in the age-metallicity diagram and estimating the birth radius of stars – is briefly illustrated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Glacial Geomorphologic Maps of Llanquihue Drift in the Area of the Southern Lake District, Chile

We present four glacial geomorphic maps of Llanquihue drift in the region of the southern Lake District, Seno Reloncaví, and the eastern half of northern Isla Grande de Chiloé, Chile. These maps form the basis of an interdisciplinary research project to establish a paleoclimate reconstruction of the last glacial cycle in the middle latitudes of the Southern Hemisphere. Therefore we stressed morphologic rather than lithologic units in our mapping program in order to delineate the glacial geomorphic forms that are surface manifestations of former ice-marginal fluctuations. The resulting maps show the lobate shape and low surface slopes of the former piedmont glaciers that, at the last glacial maximum, spread westward from the Andes into the Valle Centralto fill Lago Puyehue, Lago Rupanco, Lago Llanquihue, Seno Reloncaví, Golfo de Ancud, and northern Gulfo Corcovado. These maps are the framework to tie together in this volume the stratigraphic sections and radiocarbon samples from within the Llanquihue moraine belts as well as the pollen cores from surface mires on the belts.     

The science case of the PEPSI high‐resolution echelle spectrograph and polarimeter for the LBT

We lay out the scientific rationale for and present the instrumental requirements of a high‐resolution adaptiveoptics Echelle spectrograph with two full‐Stokes polarimeters for the Large Binocular Telescope (LBT) in Arizona. Magnetic processes just like those seen on the Sun and in the space environment of the Earth are now well recognized in many astrophysical areas. The application to other stars opened up a new field of research that became widely known as the solarstellar connection. Late‐type stars with convective envelopes are all affected by magnetic processes which give rise to a rich variety of phenomena on their surface and are largely responsible for the heating of their outer atmospheres. Magnetic fields are likely to play a crucial role in the accretion process of T‐Tauri stars as well as in the acceleration and collimation of jet‐like flows in young stellar objects (YSOs). Another area is the physics of active galactic nucleii (AGNs) , where the magnetic activity of the accreting black hole is now believed to be responsible for most of the behavior of these objects, including their X‐ray spectrum, their notoriously dramatic variability, and the powerful relativistic jets they produce. Another is the physics of the central engines of cosmic gamma‐ray bursts, the most powerful explosions in the universe, for which the extreme apparent energy release are explained through the collimation of the released energy by magnetic fields. Virtually all the physics of magnetic fields exploited in astrophysics is somehow linked to our understanding of the Sun's and the star's magnetic fields. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Precise ERS-1 orbit calculation

This analysis was performed with the GEOSAT software developed at NDRE for high-precision analysis of satellite tracking and VLBI data for geodetic and geodynamic applications.For applications to ERS-1, a realistic surface force model is used together with the Jacchia 77 atmospheric model, semi-daily drag coefficients, a 1-cpr sinusoidal along-track acceleration, and the GSFC JGM-2 gravity model. ERS-1 orbits have been derived for 5.5-day arcs of laser tracking data between July 6 and August 12, 1992. Results from overlapping orbits and comparison with precise D-PAF orbits indicate an orbital accuracy of 10–15 cm in the radial direction, ~ 60 cm in the along-track direction and ~ 15 cm in the cross-track direction.     

Wave reflection in 3D conditions

Based on recent experiments carried out in wave basin on breakwaters with armour layer of rocks and cubes, this paper examines the dependence of the reflection coefficient on wave directional spreading and obliquity. Results suggest that long-crested and short-crested waves give similar reflection. The reflection coefficient is markedly dependent on the wave angle of incidence. The performance of formulae available in the literature is checked against the new dataset and a significant improvement is proposed by including the wave obliquity factor that appears in the traditional expression for the overtopping discharge.     

A new formula for front slope recession of berm breakwaters

The front slope stability of breakwaters with a homogeneous berm was studied in a large number of two dimensional model tests at Aalborg University, Denmark. The results are presented together with a new formula for prediction of the berm recession which is the most important parameter for describing the reshaping. The formula has also been calibrated and validated against model test data from other researchers. The significance of the new design formula is that it predicts berm recession much better than the existing methods, especially in case of more stable structures.     

The effect of spatial smearing on solar Doppler measurements

A mathematical method for calculating the influence of scattered light on solar Doppler measurements is developed and presented.It is shown that the main contribution to the error signal is caused by the long range scattering component of the stray-light.The method is applied on Doppler measurements of solar rotation, and the results are compared with the observations from Stanford and Mt. Wilson that hitherto have only been crudely corrected for the effects to straylight. Some of the large scatter in the published results on the solar rotation rate is shown to be caused by a too simple parameterization of the straylight.Within the uncertainties of the current measurements it is shown that the Doppler rotation rate of the solar photosphere is equal to the sunspot tracer rotation rate.     

An Interferometric Method For Measurement Of The Detector Mtf

We present an interferometric method by which the MTF of an array detector is measured directly. The method is not relying on high quality optics and precise alignment/focusing and it is therefore straightforward to set up.