Institution
International Space Science Institute
Nonprofit•Bern, Switzerland•
About: International Space Science Institute is a nonprofit organization based out in Bern, Switzerland. It is known for research contribution in the topics: Solar wind & Comet. The organization has 120 authors who have published 858 publications receiving 25772 citations. The organization is also known as: ISSI.
Topics: Solar wind, Comet, Stars, Galaxy, Population
Papers published on a yearly basis
Papers
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TL;DR: In this article, the authors developed a numerical model that computes the production rate and non-gravitational acceleration of the nucleus of comet 67P as a function of time, taking into account its complex shape with a shape model reconstructed from OSIRIS imagery.
Abstract: Aims. We use four observational data sets, mainly from the Rosetta mission, to constrain the activity pattern of the nucleus of comet 67P/Churyumov-Gerasimenko (67P).
Methods. We developed a numerical model that computes the production rate and non-gravitational acceleration of the nucleus of comet 67P as a function of time, taking into account its complex shape with a shape model reconstructed from OSIRIS imagery. We used this model to fit three observational data sets: the trajectory data from flight dynamics; the rotation state as reconstructed from OSIRIS imagery; and the water production measurements from ROSINA of 67P. The two key parameters of our model, adjusted to fit the three data sets all together, are the activity pattern and the momentum transfer efficiency (i.e., the so-called η parameter of the non-gravitational forces).
Results. We find an activity pattern that can successfully reproduce the three data sets simultaneously. The fitted activity pattern exhibits two main features: a higher effective active fraction in two southern super-regions (~ 10 %) outside perihelion compared to the northern regions (< 4 %), and a drastic rise in effective active fraction of the southern regions (~25 − 35%) around perihelion. We interpret the time-varying southern effective active fraction by cyclic formation and removal of a dust mantle in these regions. Our analysis supports moderate values of the momentum transfer coefficient η in the range 0.6
− 0.7; values η ≤ 0.5 or η ≥ 0.8 significantly degrade the fit to the three data sets.
Our conclusions reinforce the idea that seasonal effects linked to the orientation of the spin axis play a key role in the formation and evolution of dust mantles, and in turn, they largely control the temporal variations of the gas flux.
21 citations
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TL;DR: In this article, the authors present an overview of commonly applied data analysis methods and their implication for the obtained results, and suggest that because it does not imply least-squares fitting of prescribed periodic or proxy data functions into the considered times series, time-domain analysis provides a more reliable method than multiple regression analysis for extracting decadal-scale signals from observational ozone datasets.
Abstract: Because of its chemical and radiative properties, atmospheric ozone constitutes a key element of the Earth's climate system. Absorption of sunlight by ozone in the ultraviolet wavelength range is responsible for stratospheric heating, and determines the temperature structure of the middle atmosphere. Changes in middle atmospheric ozone concentrations result in an altered radiative input to the troposphere and to the Earth's surface, with implications on the energy balance and the chemical composition of the lower atmosphere. Although a wide range of ground- and satellite-based measurements of its integrated content and of its vertical distribution have been performed since several decades, a number of uncertainties still remain as to the response of middle atmospheric ozone to changes in solar irradiance over decadal time scales. This paper presents an overview of achieved findings, including a discussion of commonly applied data analysis methods and of their implication for the obtained results. We suggest that because it does not imply least-squares fitting of prescribed periodic or proxy data functions into the considered times series, time-domain analysis provides a more reliable method than multiple regression analysis for extracting decadal-scale signals from observational ozone datasets. Applied to decadal ground-based observations, time-domain analysis indicates an average middle atmospheric ozone increase of the order of 2% from solar minimum to solar maximum, which is in reasonable agreement with model results.
21 citations
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TL;DR: In this article, the authors reported a search for similar enhancement during the 1999 Quadrantids, which have the highest mass flux of any of the major streams. And they suggested that different chemical-physical properties of the Leonid and Quadrantid streams may be responsible for the difference.
Abstract: Enhancements of the Na emission and temperature from the lunar atmosphere were reported during the Leonid meteor showers of 1995, 1997 and 1998. Here we report a search for similar enhancement during the 1999 Quadrantids, which have the highest mass flux of any of the major streams. No enhancements were detected. We suggest that different chemical–physical properties of the Leonid and Quadrantid streams may be responsible for the difference.
21 citations
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TL;DR: In this paper, the problem of interacting relativistic current sheets in self-consistent kinetic plasma simulations within the framework of the Particle-In-Cell model is addressed, where the interaction is enforced in head-on collisions of up to 10 current sheets at relativistically bulk speeds.
21 citations
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Max Planck Society1, German Aerospace Center2, University of Maryland, College Park3, University of Bern4, Open University5, INAF6, Uppsala University7, Leiden University8, Hong Kong Polytechnic University9, Space Research Institute10, University of Naples Federico II11, University of Padua12, Tel Aviv University13, Paris Observatory14, Braunschweig University of Technology15, International Space Science Institute16, University of Bremen17, Ames Research Center18, University of Winnipeg19, University of Paris20, University of Manchester21, University of Cambridge22, Spanish National Research Council23, European Space Research and Technology Centre24, National Central University25, University of Münster26, University of Warsaw27, IAC28, Queen's University Belfast29, Imperial College London30, Centre national de la recherche scientifique31, University of Nice Sophia Antipolis32, Carnegie Institution for Science33, University of Cologne34, United States Naval Research Laboratory35, Cardiff University36, ETH Zurich37
TL;DR: The Triple F ( Fresh From the Fridge) mission as mentioned in this paper was proposed to extract three sample cores of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory.
Abstract: The Triple F ( Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA's Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS.
21 citations
Authors
Showing all 122 results
Name | H-index | Papers | Citations |
---|---|---|---|
Franz E. Bauer | 118 | 939 | 58465 |
Gilles Chabrier | 95 | 384 | 40066 |
Tamas I. Gombosi | 84 | 612 | 26497 |
André Balogh | 81 | 546 | 22494 |
Isabelle Baraffe | 72 | 287 | 21612 |
Anny Cazenave | 72 | 276 | 20198 |
Travis S. Metcalfe | 70 | 239 | 17016 |
Mark Sargent | 66 | 217 | 14925 |
Nathan A. Schwadron | 65 | 495 | 16768 |
G. Paschmann | 61 | 185 | 15887 |
Joachim Wambsganss | 59 | 310 | 13732 |
J. Geiss | 56 | 191 | 9427 |
Tilman Spohn | 56 | 195 | 9042 |
Lennart Bengtsson | 55 | 210 | 13109 |
Rudolf A. Treumann | 50 | 311 | 9004 |