Stability of fictitious Trojan planets in extrasolar systems

Our work deals with the dynamical possibility that in extrasolar planetary systems a terrestrial planet may have stable orbits in a 1:1 mean motion resonance with a Jovian like planet. We studied the motion of fictitious Trojans around the Lagrangian points L₄/L₅ and checked the stability and/or chaoticity of their motion with the aid of the Lyapunov Indicators and the maximum eccentricity. The computations were carried out using the dynamical model of the elliptic restricted three‐body problem that consists of a central star, a gas giant moving in the habitable zone, and a massless terrestrial planet. We found 3 new systems where the gas giant lies in the habitable zone, namely HD99109, HD101930, and HD33564. Additionally we investigated all known extrasolar planetary systems where the giant planet lies partly or fully in the habitable zone. The results show that the orbits around the Lagrangian points L₄/L₅ of all investigated systems are stable for long times (10⁷ revolutions). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the global stability of single‐planet systems

In this paper, we estimate the global stability properties of single‐planet systems by using a catalogue of stability maps. The data of the catalogue were used to generate probability values on the mass parameter–eccentricity plane for the occurrence of stable orbits. We showed that the probability data can be well approximated by a second order surface. Using the resulted formula the likelihood of finding Earth‐like planets in single‐planet systems can be easily estimated. As an example, we derived estimations for four known exoplanetary systems. Our formula can be useful in selecting target stars for future space missions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A planetary system with an escaping Mars

The chaotic behaviour of the motion of the planets in our Solar System is well established. In this work to model a hypothetical extrasolar planetary system our Solar System was modified in such a way that we replaced the Earth by a more massive planet and let the other planets and all the orbital elements unchanged. The major result of former numerical experiments with a modified Solar System was the appearance of a chaotic window at κ _E ∈ (4, 6), where the dynamical state of the system was highly chaotic and even the body with the smallest mass escaped in some cases. On the contrary for very large values of the mass of the Earth, even greater than that of Jupiter regular dynamical behaviour was observed. In this paper the investigations are extended to the complete Solar System and showed, that this chaotic window does still exist. Tests in different ‘Solar Systems’ clarified that including only Jupiter and Saturn with their actual masses together with a more ‘massive’ Earth (4 < κ _E < 6) perturbs the orbit of Mars so that it can even be ejected from the system. Using the results of the Laplace‐Lagrange secular theory we found secular resonances acting between the motions of the nodes of Mars, Jupiter and Saturn. These secular resonances give rise to strong chaos, which is the cause of the appearance of the instability window. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Evaluation of meteorological controls of reconstructed rockfall activity in the Czech Flysch Carpathians

Rockfall is an important process in the final sculpturing of escarpments and scree slopes that originate in bedrock landslides in the Flysch Carpathians. The spatio‐temporal characteristics of rockfall activity were studied at four localities representative of old landslides in the highest part of the Czech Flysch Carpathians (Moravskoslezské Beskydy Mountains). Historical activity, chronology, and spatial context of rockfall activity were reconstructed using dendrogeomorphic techniques and rockfall rate index (RR). A total of 1132 increment cores from 283 trees growing in the rockfall transport and accumulation zones enabled the dating of 989 rockfall events. Reconstruction of a 78‐year‐long RR chronology suggests similar rockfall histories and trends at all study sites, indicating the existence of major common factors driving rockfall dynamics in the region. Temporal analysis and correlation of the RR series obtained with monthly mean temperatures, numbers of days with temperature transitions through 0 °C and monthly precipitation totals show that meteorological characteristics have evident but variable influence on rockfall activity. The most important factor is the effect of freeze–thaw cycles throughout the year, supplemented by low temperatures, especially during autumn. The influence of precipitation totals is of lesser importance. Copyright © 2011 John Wiley & Sons, Ltd.     

The Staffelegg Formation: a new stratigraphic scheme for the Early Jurassic of northern Switzerland

The deposits of the Early Jurassic in northern Switzerland accumulated in the relatively slowly subsiding transition zone between the southwestern part of the Swabian basin and the eastern part of the Paris basin under fully marine conditions. Terrigenous fine-grained deposits dominate, but calcarenitic and phosphorit-rich strata are intercalated. The total thickness varies between 25 and 50 m. In the eastern and central parts of N Switzerland, sediments Sinemurian in age constitute about 90% of the total thickness. To the West, however, in the Mont Terri area, Pliensbachian and Toarcian deposits form 70% of the total thickness. Stratigraphic gaps occur on a local to regional scale throughout N Switzerland. Such hiatus comprise a subzone to a stage in time. With respect to lithology and fossil content, the Early Jurassic deposits in northern Switzerland are similar to those in SW Germany. Nonetheless, an exact stratigraphic correlation is hardly possible, particulary in the southern and southwestern Folded Jura where distinct facies changes occur over short distances. Revised existing and new litho- and biostratigraphic data form the base to refine the stratigraphic subdivision of the deposits that have been informally called “Lias”. The name Staffelegg Formation is suggested and defined as the mapping unit for the Early Jurassic. The Staffelegg Formation is introduced for Early Jurassic sediments in northern Switzerland between the Doubs River and Mt. Weissenstein in the west and the Randen Hills located north of the city of Schaffhausen in the east. The Staffelegg Formation starts within the Planorbis zone of the Hettangian. The upper boundary to the overlying Aalenian Opalinus-Ton is diachronous. The lithostratigraphic names previously in use have been replaced by new ones, in accordance within the rules of lithostratigraphic nomenclature. The Staffelegg Formation comprises 11 members and 9 beds. Several of these beds are important correlation horizons in terms of allostratigraphy. Some of them correspond to strata or erosional unconformities encountered in the Swabian realm, some of them can be correlated with strata in the Paris basin. The facies transition to the Paris basin is expressed by introduction of a corresponding lithostratigraphic unit.     

Co-occurrence of <Emphasis Type="Italic">Neusticosaurus edwardsii</Emphasis> and <Emphasis Type="Italic">N. peyeri</Emphasis> (Reptilia) in the Lower Meride Limestone (Middle Triassic,Monte San Giorgio)

A newly opened excavation in the Cassina beds of the Lower Meride Limestone (Monte San Giorgio UNESCO World Heritage List, Canton Ticino, Switzerland), has yielded a pachypleurosaurid (Reptilia: Sauropterygia) specimen which is identified as Neusticosaurus peyeri. The resulting co-occurrence of N. peyeri and N. edwardsii, the latter so far regarded as the sole species of the genus present in this horizon, challenges the hypothesis of a single anagenetic lineage in Neusticosaurus species from Monte San Giorgio. In addition, it leads to a reconsideration of the phylogenetic inferences about Neusticosaurus evolution in the Monte San Giorgio area. The stratigraphic distribution of the Neusticosaurus species in the Monte San Giorgio basin is updated on the basis of recent finds.     

Crustal profiles of active continental collisional belt: Czechoslovak deep seismic reflection profiling in the West Carpathians

Summary. Czechoslovak deep seismic reflection profiles across the West Carpathians, the first in the Alpine-Himalayan belt, and surface geological data, suggest that the passive margin of the Eurasian plate was obliquely overriden by the upper Carpatho-Pannonian plate during the end of the Krosno sea subduction some 17-14 Ma ago. The following period was dominated by slight oblique continental collision (transpression and transtension) of the West Carpathian-East Alpine continental material escaping from the East Alpine collision zone and Eurasian Brunovistulic passive margin. Crustal shortening in the North was accommodated by significant northerly dipping backthrusting and crustal thickening. Backthrusting is clearly observable on deep seismic lines 2T and 3T. Different subsidence features are present on the deep seismic line 3T. There are active pull-apart graben in the Vienna basin, mid-Miocene (16–10 Ma) low-angle normal faulting in the Danube basin, and there is a normal simple shear zone offsetting the Moho boundary beneath the Danube basin.     

Transition spectra of dynamical systems

The spectra of ‘stretching numbers’ (or ‘local Lyapunov characteristic numbers’) are different in the ordered and in the chaotic domain. We follow the variation of the spectrum as we move from the centre of an island outwards until we reach the chaotic domain. As we move outwards the number of abrupt maxima in the spectrum increases. These maxima correspond to maxima or minima in the curve a(θ), where a is the stretching number, and θ the azimuthal angle. We explain the appearance of new maxima in the spectra of ordered orbits. The orbits just outside the last KAM curve are confined close to this curve for a long time (stickiness time) because of the existence of cantori surrounding the island, but eventually escape to the large chaotic domain further outside. The spectra of sticky orbits resemble those of the ordered orbits just inside the last KAM curve, but later these spectra tend to the invariant spectrum of the chaotic domain. The sticky spectra are invariant during the stickiness time. The stickiness time increases exponentially as we approach an island of stability, but very close to an island the increase is super exponential. The stickiness time varies substantially for nearby orbits; thus we define a probability of escape P_n(x) at time n for every point x. Only the average escape time in a not very small interval Δx around each x is reliable. Then we study the convergence of the spectra to the final, invariant spectrum. We define the number of iterations, N, needed to approach the final spectrum within a given accuracy. In the regular domain N is small, while in the chaotic domain it is large. In some ordered cases the convergence is anomalously slow. In these cases the maximum value of a_k in the continued fraction expansion of the rotation number a = [a₀,a₁,... a_k,...] is large. The ordered domain contains small higher order chaotic domains and higher order islands. These can be located by calculating orbits starting at various points along a line parallel to the q-axis. A monotonic variation of the sup {q}as a function of the initial condition q₀ indicates ordered motions, a jump indicates the crossing of a localized chaotic domain, and a V-shaped structure indicates the crossing of an island. But sometimes the V-shaped structure disappears if the orbit is calculated over longer times. This is due to a near resonance of the rotation number, that is not followed by stable islands. This revised version was published online in July 2006 with corrections to the Cover Date.     

Multiple Quaternary erosion and infill cycles in overdeepened basins of the northern Alpine foreland

The cumulative effect of repeated extensive glaciations represents a poorly constrained component in the understanding of landscape evolution in mid-latitude mountain ranges such as the Alps. Timing, extent, and paleo-climatic conditions of these glaciations are generally poorly understood due to the often-fragmentary character of terrestrial Quaternary records. In this context, the sedimentary infills of subglacial basins may serve as important archives to complement the Quaternary stratigraphy over several glacial–interglacial cycles. In this study, sedimentary facies, valley-fill architecture, and luminescence dating are used to describe nine erosional and depositional cycles (Formations A–I) in the Lower Glatt valley, northern Switzerland. These cycles can be related to the ‘Birrfeld’ Glaciation (~ MIS2), the ‘Beringen’ Glaciation (~ MIS6), and up to three earlier Middle Pleistocene glaciations that can be tentatively correlated to the regional glaciation history. Evidence suggests that deep bedrock trough incision and/or partial re-excavation last occurred mainly during the ‘Beringen’ and ‘Habsburg’ Glaciations. Second-order, ‘inlaid’ glacial basins document separate glacier re-advances during the Beringen Glaciation. The arrangement of subglacial basins in the Glatt valley with different sub-parallel or bifurcating bedrock troughs, re-excavated segments, and inlaid basins document changes in the magnitude and the spatial focus of subglacial erosion over time. The Glatt valley may thus serve as a key example for the glacial landscape evolution in many other repeatedly glaciated forelands.     

Assessing the saltwater remediation potential of a three-dimensional,heterogeneous, coastal aquifer system

This paper evaluates the remediation potential of a salinized coastal aquifer by utilizing a scenario simulation. Therefore, the numerical model OpenGeoSys is first validated against analytical and experimental data to represent transient groundwater level development and variable density saline intrusion. Afterwards, a regional scale model with a three-dimensional, heterogeneous hydrogeology is calibrated for a transient state and used to simulate a best-case scenario. Water balances are evaluated in both the transient calibration and scenario run. Visualization techniques help to assess the complex model output providing valuable insight in the occurring density-driven flow processes. Furthermore, modeling and visualization results give information on the time scale for remediation activities and, due to limitations in data quality and quantity reveal potential for model improvement.