Abstract
We investigate formation of close-in terrestrial planets from planetary
embryos under the influence of a hot Jupiter (HJ) using gravitational N-body
simulations that include gravitational interactions between the gas disk and
the terrestrial planet (e.g., type I migration). Our simulations show that
several terrestrial planets efficiently form outside the orbit of the HJ,
making a chain of planets, and all of them gravitationally interact directly or
indirectly with the HJ through resonance, which leads to inward migration of
the HJ. We call this mechanism of induced migration of the HJ as "crowding
out." The HJ is eventually lost by collision with the central star, and only
several terrestrial planets remain. We also find that the efficiency of the
crowding-out effect depends on model parameters; for example, the heavier the
disk is, the more efficient the crowding out is. When planet formation occurs
in a massive disk, the HJ can be lost to the central star and is never
observed. On the other hand, for a less massive disk, the HJ and terrestrial
planets can coexist; however, the companion planets can be below the detection
limit of current observations. In both cases, systems with the HJ and
terrestrial planets have little chance for detection. Therefore, our model
naturally explains the lack of companion planets in HJ systems regardless of
the disk mass. In effect, our model provide a theoretical prediction for future
observations; additional planets can be discovered just outside the HJ, and
their masses should generally be small.
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