The dynamic mature of the Adams ring arcs - Fraternite, Egalite (2,1), Liberte, Courage

By considering the finite mass of Fraternite, the dynamic nature of the Adams ring arcs is regarded as caused by the reaction of a test body (a minor arc) through the Lindblad resonance (LR). Assumming the eccentricity of the test body is larger than that of Galatea, this generates several locations along the ring in the neighborhood of Fraternite where the time averaged force on a test body vanishes. These locations appear to correspond to the time dependent configuration of Egalite (2,1), Liberte, and Courage, and seem to be able to account for the dynamics of the arcs. Such a configuration is a dynamic one because the minor arcs are not bounded by the corotation eccentricity resonance (CER) externally imposed by Galatea, but are self-generated by LR reacting to the external fields

Padrões de beta diversidade filogenética de anuros na Mata Atlântica

Orientador: Mauricio Osvaldo de MouraMonografia (Bacharelado) - Universidade Federal do Paraná. Setor de Ciências Biológicas. Curso de Graduação em Ciências Biológica

Forças de radiações eletromagneticas sobre corpos esfericos em movimento translacional e rotacional

Orientador: Germano Bruno AfonsoDissertação (mestrado) - Universidade Federal do ParanaResumo: Desenvolve-se um modelo dependente do tempo para as forcas translacionais de radiações eletromagnéticas tanto para as absorvidas e espalhadas como também para as termicamente emitidas. Resolvendo-se uma equação dependente do tempo para a difusão de energia térmica, mostra-se que os efeitos conhecidos na literatura cientifica como Yarkovsky e Invemo-VerSo sao casos particulares de um mesmo fenômeno que e o da existência de uma inércia térmica característica. Extende-se o modelo para os casos que envolvem fontes de radiações eletromagnéticas de dimensões finitas, e aplicam-se os resultados obtidos para o satélite CASTOR. Utilizando-se o tratamento relativístico restrito, extraem-se os efeitos conhecidos como Poynting-Robertson e Doppler-Diferencial. Desenvolve-se também o modelo para as forcas rotacionais de radiações eletromagnéticas.Abstract: A time dependent model is developed for the translational electromagnetic radiation force due to the radiation absortion and scattering as well as to the thermal radiation emission, A time dependent thermal energy difusion equation is solved to show that the well know Yarkovsky and Summer-Winter effects are particular cases of the same phenomenon: the thermal inertia existence. The model is extended for finit dimensions electromagnetic radiation source, and its results are applied to CASTOR satellite. By using the special relativistic treatment, the known Poynting-Robertson and Doppler-Diferential effects were easy obtained. A rotational electromagnetic radiation force is also develloped

OSS (Outer Solar System): A fundamental and planetary physics mission to Neptune, Triton and the Kuiper Belt

The present OSS mission continues a long and bright tradition by associating the communities of fundamental physics and planetary sciences in a single mission with ambitious goals in both domains. OSS is an M-class mission to explore the Neptune system almost half a century after flyby of the Voyager 2 spacecraft. Several discoveries were made by Voyager 2, including the Great Dark Spot (which has now disappeared) and Triton's geysers. Voyager 2 revealed the dynamics of Neptune's atmosphere and found four rings and evidence of ring arcs above Neptune. Benefiting from a greatly improved instrumentation, it will result in a striking advance in the study of the farthest planet of the Solar System. Furthermore, OSS will provide a unique opportunity to visit a selected Kuiper Belt object subsequent to the passage of the Neptunian system. It will consolidate the hypothesis of the origin of Triton as a KBO captured by Neptune, and improve our knowledge on the formation of the Solar system. The probe will embark instruments allowing precise tracking of the probe during cruise. It allows to perform the best controlled experiment for testing, in deep space, the General Relativity, on which is based all the models of Solar system formation. OSS is proposed as an international cooperation between ESA and NASA, giving the capability for ESA to launch an M-class mission towards the farthest planet of the Solar system, and to a Kuiper Belt object. The proposed mission profile would allow to deliver a 500 kg class spacecraft. The design of the probe is mainly constrained by the deep space gravity test in order to minimise the perturbation of the accelerometer measurement.Comment: 43 pages, 10 figures, Accepted to Experimental Astronomy, Special Issue Cosmic Vision. Revision according to reviewers comment

Planetary Rings

Planetary rings are the only nearby astrophysical disks, and the only disks that have been investigated by spacecraft. Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 1e-7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close-range and in real-time in planetary rings. We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The main rings of Saturn comprise our system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty rings, likely generated by embedded source bodies, are surprisingly found to sport azimuthally-confined arcs. Finally, every known ring system includes a substantial component of diffuse dusty rings. Planetary rings have shown themselves to be useful as detectors of planetary processes around them, including the planetary magnetic field and interplanetary impactors as well as the gravity of nearby perturbing moons. Experimental rings science has made great progress in recent decades, especially numerical simulations of self-gravity wakes and other processes but also laboratory investigations of coefficient of restitution and spectroscopic ground truth. The age of self-sustained ring systems is a matter of debate; formation scenarios are most plausible in the context of the early solar system, while signs of youthfulness indicate at least that rings have never been static phenomena.Comment: 82 pages, 34 figures. Final revision of general review to be published in "Planets, Stars and Stellar Systems", P. Kalas and L. French (eds.), Springer (http://refworks.springer.com/sss

Étude numérique des anneaux planétaires

We consider in this work the dynamics of narrow planetary rings with low optical depth. For many of these rings, nearby satellites seem to have a crucial importance on the long term evolution of features like sharp edges, clumps, diffuse and multiple components, braids, arcs, etc … To study this kind of rings, we have developed a fast numerical code based on the impulse approximation, which describes the interactions with the satellite(s). The model also takes into account the effects of radiation forces (radiation pressure and Poynting-Robertson drag), and collisions between particles. We study in details the Lindblad and corotation mean motion resonances, both in the horizontal and vertical directions. The code is used to explore the stability of Neptune ring arcs. We show that the satellite Galatea is able to confine radially and azimuthally the particles in corotation sites, and that these structures thus obtained are in good agreement with the observations. This allows us to propose a model for the origin of this ring. The latter would be composed by a small number of large particles. Collisions between these bodies would produce dust which is subsequently captured in the corotation sties, forming arcs. Then, non gravitational forces and stochastic diffusion from one site to the other, may cause the escape of the particles from the arcs, explaining the continuous ring.Nous considérons dans ce travail la dynamique des anneaux étroits à faible épaisseur optique. Pour beaucoup de ces anneaux, des satellites proches semblent avoir une influence prépondérante sur l'évolution à long terme des structures telles que des bords nets, des grumeaux plus brillants, des composantes diffuses et multiples, des tresses, arcs, etc pour étudier les anneaux, nous avons développé un code numérique rapide base sur l'approximation d'impulsion qui décrit l'interaction avec le(s) satellite(s). Le modèle prend aussi en compte les effets dus aux forces de radiation (pression de radiation et effet Poynting-Robertson), et les collisions entre les particules. Nous étudions en détail les résonances de moyen mouvement de Lindblad et de corotation, aussi bien horizontales que verticales. Le code est utilisé pour explorer numériquement la stabilité des arcs de Neptune. Nous montrons que le satellite Galatea est capable de confiner radialement et azimutalement des particules sur des sites de corotation, et que les structures obtenues sont en bon accord avec celles qui sont observées dans l'anneau Adams et ses arcs. Cela nous permet alors de proposer un modèle pour l'origine de cet anneau. L’anneau serait composé d'un petit nombre de grosses particules. Les collisions entre ces corps parents génèrent de la poussière qui se piègent sur les sites de corotation en formant les arcs. Puis les forces de radiation et les collisions les font échapper des résonances et diffuser lentement, formant ainsi l'anneau continu

Forças de radiações eletromagneticas sobre corpos esfericos em movimento translacional e rotacional

Orientador: Germano Bruno AfonsoDissertação (mestrado) - Universidade Federal do ParanaResumo: Desenvolve-se um modelo dependente do tempo para as forcas translacionais de radiações eletromagnéticas tanto para as absorvidas e espalhadas como também para as termicamente emitidas. Resolvendo-se uma equação dependente do tempo para a difusão de energia térmica, mostra-se que os efeitos conhecidos na literatura cientifica como Yarkovsky e Invemo-VerSo sao casos particulares de um mesmo fenômeno que e o da existência de uma inércia térmica característica. Extende-se o modelo para os casos que envolvem fontes de radiações eletromagnéticas de dimensões finitas, e aplicam-se os resultados obtidos para o satélite CASTOR. Utilizando-se o tratamento relativístico restrito, extraem-se os efeitos conhecidos como Poynting-Robertson e Doppler-Diferencial. Desenvolve-se também o modelo para as forcas rotacionais de radiações eletromagnéticas.Abstract: A time dependent model is developed for the translational electromagnetic radiation force due to the radiation absortion and scattering as well as to the thermal radiation emission, A time dependent thermal energy difusion equation is solved to show that the well know Yarkovsky and Summer-Winter effects are particular cases of the same phenomenon: the thermal inertia existence. The model is extended for finit dimensions electromagnetic radiation source, and its results are applied to CASTOR satellite. By using the special relativistic treatment, the known Poynting-Robertson and Doppler-Diferential effects were easy obtained. A rotational electromagnetic radiation force is also develloped