Search results for "Planetary Science"
showing 10 items of 4367 documents
CGCG 480-022: A Distant Lonesome Merger?
2006
[EN]We present a complete analysis, which includes morphology, kinematics, stellar populations, and N-body simulations, of CGCG 480-022, the most distant (cz = 14,317 km s-1) isolated galaxy studied so far in such detail. The results all support the hypothesis that this galaxy has suffered a major merger event with a companion of ~0.1 times its mass. Morphology reveals the presence of a circumnuclear ring and possibly further ring debris. The radial velocity curve looks symmetrical, while the velocity dispersion increases with radius, reaching values that do not correspond to a virialized system. Moreover, this galaxy deviates significantly from the fundamental plane and the Faber-Jackson r…
The ALHAMBRA survey: 2D analysis of the stellar populations in massive early-type galaxies atz< 0.3
2017
Reproduced with permission from Astronomy & Astrophysics
The Gaia-ESO survey: Discovery of a spatially extended low-mass population in the Vela OB2 association
2015
The nearby (distance~350-400 pc), rich Vela OB2 association, includes $\gamma^2$ Velorum, one of the most massive binaries in the solar neighbourhood and an excellent laboratory for investigating the formation and early evolution of young clusters. Recent Gaia-ESO survey observations have led to the discovery of two kinematically distinct populations in the young (10-15 Myr) cluster immediately surrounding $\gamma^2$ Velorum. Here we analyse the results of Gaia-ESO survey observations of NGC 2547, a 35 Myr cluster located two degrees south of $\gamma^2$ Velorum. The radial velocity distribution of lithium-rich pre-main sequence stars shows a secondary population that is kinematically distin…
The Second APOKASC Catalog: The Empirical Approach
2018
We present a catalog of stellar properties for a large sample of 6676 evolved stars with APOGEE spectroscopic parameters and \textit{Kepler} asteroseismic data analyzed using five independent techniques. Our data includes evolutionary state, surface gravity, mean density, mass, radius, age, and the spectroscopic and asteroseismic measurements used to derive them. We employ a new empirical approach for combining asteroseismic measurements from different methods, calibrating the inferred stellar parameters, and estimating uncertainties. With high statistical significance, we find that asteroseismic parameters inferred from the different pipelines have systematic offsets that are not removed b…
Stochastic response of combined primary-secondary structures under seismic input
1992
A technique for non-stationary stochastic analysis of linear combined primary and secondary subsystems subjected to a zero-mean Gaussian base excitation is presented. The proposed technique, based on the use of the Taylor's expansion in evaluating the operators which appear in the step-by-step procedure, does not require the evaluation of the complex eigenproperties of the combined system. Operating in this way, even though the numerical procedure is a conditionally stable one, appears to be more efficient than existing methods to evaluate the dynamic response of such composite systems. It is also shown that the proposed procedure is available whether the seismic input is idealized as a fil…
Combined dynamic response of primary and multiply connected cascaded secondary subsystems
1991
A method is proposed for the deterministic and stochastic non-stationary analysis of linear composite systems with cascaded secondary subsystems subjected to a seismic input. This method makes it possible to evaluate, by means of a unitary formulation, the deterministic and non-stationary stochastic response of both classically and non-classically damped subsystems and of secondary subsystems multiply supported on the primary one, as well as the ground. The proposed procedure is very efficient from a computational point of view, because of the Kronecker algebra systematically employed. Indeed, by using this algebra, it is possible to obtain in a very compact and elegant form the eigenproper…
A paradigm of extreme rainfall pluvial floods in complex urban areas: the flood event of 15 July 2020 in Palermo (Italy)
2021
Abstract. In the last few years, some regions of the Mediterranean area have witnessed a progressive increase in extreme events, such as urban and flash floods, as a response to the increasingly frequent and severe extreme rainfall events, which are often exacerbated by the ever-growing urbanization. In such a context, the urban drainage systems may not be sufficient to convey the rainwater, thus increasing the risk deriving from the occurrence of such events. This study focuses on a particularly intense urban flood that occurred in Palermo (Italy) on 15 July 2020; it represents a typical pluvial flood due to extreme rainfall on a complex urban area that many cities have experienced in rece…
Pianificazione strategica tra sviluppo locale e policentrismo: alcune evidenze empiriche sul caso siciliano
2009
Strategic planning, local development and policentrism: empirical evidence for Sicily The aim of this paper is the analysis of metropolitan strategic planning in Sicily. Urban areas are becoming important units for territorial cohesion policy and strategic planning represents more and more an important policy instrument. Evidence of a policentric pattern is tested across 30 strategic plans carried out by Sicilian cities in order to derive useful insights for policy implications. Methods and Results This study uses multidimensional scaling and rank-size regressions across Sicilian Functional Urban Areas (FUA) as well as descriptive information drawn from strategic plans in order to identify …
OSL dating of sediments from the Gobi Desert, Southern Mongolia
2010
Abstract The present study focuses on the chronological relationship between alternating dune sand and silty water-lain sediments in the central part of the Khongoryn Els dune field in the Gobi Desert, Southern Mongolia. The 23 m high section evolved from the construction of a natural dam by west–east moving sand dunes and fluvial inundation by a river system from the mountain ranges in the south. To resolve the chronology of events, optically stimulated luminescence (OSL) dating was applied and from sedimentological and geochemical analysis the depositional processes could be characterised. Quartz OSL dating of these sediments is hindered by feldspar contamination. Thus, dating of coarse-g…
On the thermodynamics of listric faults
2004
We investigate a novel fully coupled thermal-mechanical numerical model of the crust in order to trace the physics of interaction of its brittle and ductile layers. In a unified approach these layers develop in a natural transition as a function of the state variables pressure, deviatoric stress, temperature and strain-rate. We find that the main storage of elastic energy lies in the domain where brittle and ductile strain-rates overlap so that shear zones are attracted to this zone of maximum energy dissipation. This dissipation appears as a local heat source (shear heating). The brittle-ductile transition zone evolves through extreme weakening by thermo-mechanical feedback. The physics of…