Satélites irregulares de júpiter: configurações propícias do processo de captura de asteróides binários
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Data
2009-08-29
Autores
Gaspar, Helton da Silva [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A existência de satélites irregulares é um tema de interesse científico há muito tempo devido às suas características peculiares, isto é, órbitas bem excêntricas, distantes do planeta e geralmente com altas inclinações em relação ao plano equatorial de seu planeta, chegando a ser em grande parte retrógradas. A existência de famílias de satélites irregulares, caracterizadas pela semelhança dos elementos orbitais dos satélites que as compõem é, ainda hoje, um fato não explicado. Tais características sugerem que os satélites irregulares não tenham sido formados juntamente com os planetas que estes orbitam, como se acredita ser o caso dos satélites regulares. Deste modo, uma explicação coerente para a existência dos mesmos é a captura gravitacional de corpos, formados em outras regiões, a partir de órbitas heliocêntricas após a ocorrência de um encontro próximo com o planeta. Entretanto, sob a dinâmica do Problema Circular Restrito de Três Corpos - PCR3C - capturas gravitacionais têm carater temporário, o que torna necessária a existência de um mecanismo de captura auxiliar. Isto tem incentivado, por anos, à proposição de vários modelos para explicar a existência dos satélites irregulares através da captura gravitacional, dentre os quais três se destacam na literatura: Dissipação por arrasto em gás, Pull-down capture – captura por puxão, interação colisional ou por encontros próximos com satélites pré-existentes, capturas de planetesimais durante encontros planetários e captura de asteróides binários. Considerando a dinâmica de 4-Corpos, investigamos numericamente a viabilidade de um modelo no qual um ente de um asteróide binário é capturado após sofrer um encontro próximo com um Júpiter, avaliando as condições que propiciam a captura de cada um dos membros, realizando um mapeamento dos parâmetros de modo...
The existence of irregular satellites has been the focus of scientific interest for many years. That is due to their peculiar orbital features, i.e., highly eccentric orbits, large distance from the planet and, usually, with high inclination and many of them are retrograde. There are very well characterized families of irregular satellites, whose origin were not explained yet. These features suggest that irregular satellites were not formed together with the planet, during its formation stage, as were the regular ones. Therefore, an explanation for their existence is the gravitational capture of asteroids, originally in heliocentric orbits, that had a close encounter with the planet. However, considering only the Restrict Three Body Problem dynamics, it is not possible to accomplish permanent captures, being necessary the existence of an auxiliary mechanism. Then, several models were proposed in order to generate a permanent capture. Among the most important we found Gas drag dissipation, Pull-down capture, collisional and close encounters interactions with regular satellites, capture during planetary encounters and capture of binary asteroids. The current research had assessed how viable is a 4-body mechanism in which a member body of a binary asteroid remain captured after a close encounter with Jupiter. In order to accomplish that, we have mapped a set o parameters in order to find the proper conditions to yield the capture of one member. From the main results it is shown a very well permanent capture probability of the minor member when the primordial binary asteroid disrupts at a suitable “quadrature” configuration. Finally, it is also shown that this capture mechanism is well explained through energy exchanges.
The existence of irregular satellites has been the focus of scientific interest for many years. That is due to their peculiar orbital features, i.e., highly eccentric orbits, large distance from the planet and, usually, with high inclination and many of them are retrograde. There are very well characterized families of irregular satellites, whose origin were not explained yet. These features suggest that irregular satellites were not formed together with the planet, during its formation stage, as were the regular ones. Therefore, an explanation for their existence is the gravitational capture of asteroids, originally in heliocentric orbits, that had a close encounter with the planet. However, considering only the Restrict Three Body Problem dynamics, it is not possible to accomplish permanent captures, being necessary the existence of an auxiliary mechanism. Then, several models were proposed in order to generate a permanent capture. Among the most important we found Gas drag dissipation, Pull-down capture, collisional and close encounters interactions with regular satellites, capture during planetary encounters and capture of binary asteroids. The current research had assessed how viable is a 4-body mechanism in which a member body of a binary asteroid remain captured after a close encounter with Jupiter. In order to accomplish that, we have mapped a set o parameters in order to find the proper conditions to yield the capture of one member. From the main results it is shown a very well permanent capture probability of the minor member when the primordial binary asteroid disrupts at a suitable “quadrature” configuration. Finally, it is also shown that this capture mechanism is well explained through energy exchanges.
Descrição
Palavras-chave
Satelites, Asteroides, Irregular Satellites, Binary Asteroids, Gravitational Capture
Como citar
GASPAR, Helton da Silva. Satélites irregulares de júpiter: configurações propícias do processo de captura de asteróides binários. 2009. 44 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Engenharia de Guaratinguetá, 2009.