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The rapid growth via pebble accretion allows the cores to grow large enough to accrete massive gas envelopes forming gas giants while avoiding migrating very close to the star. In simulations, cold gas giants like Jupiter and Saturn can form via pebble accretion if their initial embryos began growing beyond 20 AU. This distant formation offers ...
Pebble accretion may accelerate the formation of planets by a factor of 1000 compared to the accretion of planetesimals, allowing giant planets to form before the dissipation of the gas disk. [28] [29] However, core growth via pebble accretion appears incompatible with the final masses and compositions of Uranus and Neptune. [30]
In this model giant planet formation is divided into two stages: a) accretion of a core of approximately 10 M E and b) accretion of gas from the protoplanetary disk. [2] [22] [67] Either method may also lead to the creation of brown dwarfs. [31] [68] Searches as of 2011 have found that core accretion is likely the dominant formation mechanism. [68]
[46] [47] If most of the growth of planetesimals and embryos into terrestrial planets was due to pebble accretion, a small Mars could be the result this process having been less efficient with increasing distances from the Sun. [48] [49] Convergent migration of planetary embryos in the gas disk toward 1 AU would result in the formation of ...
However, the current understanding of Earth's formation allows for less than 1% of Earth's material accreting after the Moon formed, implying that the material accreted later must have been very water-rich. Models of early Solar System dynamics have shown that icy asteroids could have been delivered to the inner Solar System (including Earth ...
The theory has two main points that seek to explain the formation of regularly spaced beach cusps. The first is that positive feedback between the morphology of the beach and the flow of the water creates relief patterns. On a flat beach, surface areas will develop with a slightly lower relief than their surroundings.
The capture model fails to explain the similarity in these isotopes (if the Moon had originated in another part of the Solar System, those isotopes would have been different), while the co-accretion model cannot adequately explain the loss of water (if the Moon formed similarly to the Earth, the amount of water trapped in its mineral structure ...
The anhydrous nature of the crust on Venus prevents it from sliding past each other, whereas through the study of oxygen isotopes, the presence of water on Earth can be confirmed from 4.3 Ga. [22] Thus, this model helps provide a mechanism for how plate tectonics could have been triggered on Earth, although it does not demonstrate that ...