Symmetries and Rank Deficiency in the Orbit Determination Around Another Planet   总被引：1，自引：0，他引：1  

Claudio Bonanno  Andrea Milani 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):17-33

We study the possible degeneracies for the normal matrix of the observations from the Earth of the motion of a satellite around a planet, and give the possible solutions to the loss of precision in the orbit determination caused by the rank deficiency. Finally we discuss the methods available to control the instability in the orbit determination resulting from the degeneracy.  相似文献   

Instruments, Detectors and the Future of Astronomy with Large Ground Based Telescopes     

Douglas A. Simons  Paola Amico  Dietrich Baade  Sam Barden  Randall Campbell  Gert Finger  Kirk Gilmore  Roland Gredel  Paul Hickson  Steve Howell  Norbert Hubin  Andreas Kaufer  Ralf Kohley  Philip MacQueen  Sergej Markelov  Mike Merrill  Satoshi Miyazaki  Hidehiko Nakaya  Darragh O'Donoghue  Tino Oliva  Andrea Richichi  Derrick Salmon  Ricardo Schmidt  Hongjun Su  Simon Tulloch  Maria Luisa García Vargas  R. Mark Wagner  Olivier Wiecha  Binxun Ye 《Experimental Astronomy》2005,19(1-3):15-44

Results of a survey of instrumentation and detector systems, either currently deployed or planned for use at telescopes larger than 3.5 m, in ground based observatories world-wide, are presented. This survey revealed a number of instrumentation design trends at optical, near, and mid-infrared wavelengths. Some of the most prominent trends include the development of vastly larger optical detector systems (> 10⁹ pixels) than anything built to date, and the frequent use of mosaics of near-infrared detectors – something that was quite rare only a decade ago in astronomy. Some future science applications for detectors are then explored, in an attempt to build a bridge between current detectors and what will be needed to support the research ambitions of astronomers in the future.  相似文献   

Astrophysical Jet Simulations: Comparing Different Numerical Methods     

Andrea Mignone  Silvano Massaglia  Gianluigi Bodo 《Astrophysics and Space Science》2004,293(1-2):199-207

High resolution Godunov-type methods have gained increasing popularity in the last decade due to their ability in modelling highly supersonic flows. Most of these shock-capturing schemes are based on the solution of the Riemann problem between discontinuous data at each cell's interface. The purpose of this work is to investigate the role played by different Riemann solvers in the evolution of a supersonic jet. Morphology, dynamics, conservation properties and cocoon characteristics are examined for the four different cases presented.  相似文献   

Strong gravitational lensing and dynamical dark energy     

Andrea V. Macciò 《Monthly notices of the Royal Astronomical Society》2005,361(4):1250-1256

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First estimates of the fundamental parameters of the relatively bright Galactic open cluster NGC 5288     

Andrés E. Piatti  Juan J. Clariá  Andrea V. Ahumada 《Monthly notices of the Royal Astronomical Society》2006,367(2):599-610

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Annual trace element cycles in calcite–aragonite speleothems: evidence of drought in the western Mediterranean 1200–1100 yr BP     

Emily A. McMillan  Ian J. Fairchild  Silvia Frisia  Andrea Borsato  Frank McDermott 《第四纪科学杂志》2005,20(5):423-433

Each of two calcitic stalagmites from Grotte de Clamouse, Herault, southern France, displays a discrete aragonite layer dated at around 1100 yr BP. The layer of fanning aragonite ray crystals is immediately preceded by calcite with Mg and Sr compositions that are uniquely high for the past 3 kyr. Trace element compositions close to the boundary between original aragonite and calcite are consistent with quasi‐equilibrium partitioning of trace elements between the phases. Study of modern dripwaters demonstrates that pronounced covariation of Mg/Ca and Sr/Ca ratios in dripwater occurs owing to large amounts of calcite precipitation upflow of the drips that fed the stalagmites. Trace element to Ca ratios are enhanced during seasonally dry periods. Ion microprobe data demonstrate a pronounced covariation of trace elements, including Mg and Sr in calcite, and Sr, U and Ba in aragonite. The mean peak spacing is close to the long‐term mean of annual growth rates determined by differences in U‐series ages and so the trace element peaks are interpreted as annual. The trace element chemistry of the stalagmites on annual to inter‐annual scales thus directly reflects the amounts of prior calcite precipitation, interpreted as an index of aridity. The longer‐term context is a multi‐decadal period of aridity (1200–1100 yr BP) possibly correlated with an analogous episode in Central America. The arid period culminated in the nucleation of aragonite, but within a decade was followed by a return to precursor conditions. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Catastrophic fragmentation and formation of families: Preliminary results from a new numerical model     

Paolo Paolicchi  Andrea Verlicchi  Alberto Cellino 《Celestial Mechanics and Dynamical Astronomy》1993,57(1-2):49-56

Preliminary results of an improved version of the semiempirical model for catastrophic break up processes developed by Paolicchi et al., (1989) are presented. Among the several changes with respect to the old version, the most important seem to be related to the new treatment of gravitational effects, including self-compression and reaccumulation of fragments. In particular, the new model is able to analyze processes involving both cm-sized objects, like those studied by means of laboratory experiments, as well as much larger bodies, for which self-gravitational effects are dominant; moreover, in this latter case the model seems in principle adequate to describe with the same physics very different phenomena, like the formation of plausible asteroid families and the creation of single, rapidly spinning, objects. This fact, if confirmed by refined analyses, may be of high importance for our general understanding of asteroid collisional evolution.  相似文献   

A Fundamental Plane of black hole activity   总被引：1，自引：0，他引：1  

Andrea Merloni  Sebastian Heinz  Tiziana Di Matteo 《Monthly notices of the Royal Astronomical Society》2003,345(4):1057-1076

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Biomonitoring of Atmospheric Heavy Metal Deposition by Mosses in the Vicinity of Industrial Sites   总被引：2，自引：0，他引：2  

Harald G. Zechmeister  Alarich Riss  Andrea Hanus-Illnar 《Journal of Atmospheric Chemistry》2004,49(1-3):461-477

At four industrial regions, heavy metal concentrations and calculated depositions were investigated by sampling and analysing mosses. In each region, a special spatial pattern of heavy metal concentrations was detected, reflecting the industrial processes. Metals most likely originating from the industrial sites showed an exponential decrease of concentrations and depositions with increasing distance from the pollution source. The exponential deposition pattern was in some cases modified by a series of natural factors, like the main direction of winds or orographic conditions. The distance at which deposition dropped to background values was up to 20 km. Beside the fact that the moss-metho is a useful tool for deposition measurement in the vicinity of stationary sources, some improvements for using this method are discussed, highlighting factors such as a proper calculation of deposition from concentrations, or the better knowledge of correlations between heavy metal concentrations in mosses and effects on human health.  相似文献   

Erratum to: Mission design,operation and exploitation of the Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission     

Rune?FloberghagenEmail author  Michael?Fehringer  Daniel?Lamarre  Danilo?Muzi  Bj?rn?Frommknecht  Christoph?Steiger  Juan?Pi?eiro  Andrea?da?Costa 《Journal of Geodesy》2012,86(3):241-241

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