Formação de planetas terrestres: o caso de acreções ineficientes
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Data
2018-11-26
Autores
Oliveira, Patrick Franco de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Estudos de formação planetária são normalmente baseados em simulações numéricas de N-corpos, onde as colisões envolvendo planetesimais e embriões são geralmente consideradas construtivas, ou seja, geram um novo corpo cuja massa é a soma das massas dos planetas envolvidos e o momento linear total é conservado. Essa aproximação funciona razoavelmente bem para a formação da Terra, Vênus e Marte. Entretanto, o planeta Mercúrio apresenta características que o classificam como sendo um corpo formado basicamente de núcleo, devido à estreita camada de manto. Isso supostamente seria consequência de acreções ineficientes, em que dois corpos em estágio avançado de formação (protoplanetas) colidem e resultam em dois outros corpos com parte da matéria podendo ser perdida. Este tipo de informação pode ser obtida a partir de simulações numéricas em que sejam registradas as condições de colisão. Aqui, nós utilizamos parâmetros para nos ajudar a analisar as colisões, a eterminar colisões de acreção ineficiente e, posteriormente analisar se estas colisões levar a condição da formação de um planeta como Mercúrio de acordo com os cenários propostos por alguns trabalhos, tais como Asphaug & Reufer (2014). Nesse sentido, realizamos simulações baseadas nos modelos de simulações numéricas de N-corpos conforme Izidoro et al. (2014), analisamos as simulações numéricas de Izidoro et al. (2015) e reproduzimos os mapas dos resultados de colisão a partir das leis de escala determinadas por Leinhardt & Stewart (2012) a fim de determinar os casos de acreções ineficientes (regimes de acreção parcial, hit-and-run e erosão). Com isso, conseguimos encontrar casos de análogos a Mercúrio nas simulações.
Planetary formation studies are usually based on numerical simulations of N-bodies, where collisions involving planetesimals and embryos are generally considered constructive, that is, they generate a new body whose mass is the sum of the masses of the planets involved and the total linear momentum is preserved. This approximation works reasonably well for the formation of Earth, Venus, and Mars. However, the planet Mercury presents characteristics that classify it as being a body basically formed of core, due to the narrow layer of mantle. This is supposed to be a consequence of inefficient accretions, in which two bodies in advanced stage of formation (protoplanets) collide and result in two other main bodies with part of the matter being able to be lost. This type of information can be obtained from numerical simulations in which the collision conditions are recorded. Here, we used parameters to help us analyze collisions, to determine collisions of inefficient accretion and then analyze if these collisions lead to the condition of the formation of a planet like Mercury according to the scenarios proposed by some works, such as Asphaug and Reufer (2014). In this sense, we perform simulations based on numerical simulations of N-bodies as Izidoro et al. (2014), we analyzed the numerical simulations of Izidoro et al. (2015) and we reproduce the maps of the collision results from the scaling laws derived by Leinhardt Stewart (2012) to determine cases of inefficient accretions (partial accretion, hit-and-run and erosion regimes). With this, we could find cases of Mercury-analogues in the simulations.
Planetary formation studies are usually based on numerical simulations of N-bodies, where collisions involving planetesimals and embryos are generally considered constructive, that is, they generate a new body whose mass is the sum of the masses of the planets involved and the total linear momentum is preserved. This approximation works reasonably well for the formation of Earth, Venus, and Mars. However, the planet Mercury presents characteristics that classify it as being a body basically formed of core, due to the narrow layer of mantle. This is supposed to be a consequence of inefficient accretions, in which two bodies in advanced stage of formation (protoplanets) collide and result in two other main bodies with part of the matter being able to be lost. This type of information can be obtained from numerical simulations in which the collision conditions are recorded. Here, we used parameters to help us analyze collisions, to determine collisions of inefficient accretion and then analyze if these collisions lead to the condition of the formation of a planet like Mercury according to the scenarios proposed by some works, such as Asphaug and Reufer (2014). In this sense, we perform simulations based on numerical simulations of N-bodies as Izidoro et al. (2014), we analyzed the numerical simulations of Izidoro et al. (2015) and we reproduce the maps of the collision results from the scaling laws derived by Leinhardt Stewart (2012) to determine cases of inefficient accretions (partial accretion, hit-and-run and erosion regimes). With this, we could find cases of Mercury-analogues in the simulations.
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Palavras-chave
Colisões, Formação Planetária, Mercúrio, Collisions, Planet Formation, Mercury, Planetas, Métodos de simulação