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An Icy Leftover Planetesimal Orbiting the Sun is; Planetesimal; Nebular Theory; Nebular Hypothesis;

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Giant planet core formation is thought to proceed roughly along the lines of the terrestrial planet formation. It starts with planetesimals that undergo runaway growth, followed by the slower oligarchic stage. Hypotheses do not predict a merger stage, due to the low probability of collisions between planetary embryos in the outer part of planetary systems. An additional difference is the composition of the , which in the case of giant planets form beyond the so-called and consist mainly of ice—the ice to rock ratio is about 4 to 1. This enhances the mass of planetesimals fourfold. However, the minimum mass nebula capable of terrestrial planet formation can only form 1–2 cores at the distance of Jupiter (5 AU) within 10 million years. The latter number represents the average lifetime of gaseous disks around Sun-like stars. The proposed solutions include enhanced mass of the disk—a tenfold increase would suffice; protoplanet migration, which allows the embryo to accrete more planetesimals; and finally accretion enhancement due to in the gaseous envelopes of the embryos. Some combination of the above-mentioned ideas may explain the formation of the cores of gas giant planets such as and perhaps even . The formation of planets like and is more problematic, since no theory has been capable of providing for the in situ formation of their cores at the distance of 20–30 AU from the central star. One hypothesis is that they initially accreted in the Jupiter-Saturn region, then were scattered and migrated to their present location.

Thomas Chrowder Chamberlin created the Planetesimal theory, which was spawned by an attempt to test the Nebular hypothesis

Characteristics Mass, radius, and temperature

Giant planet core formation is thought to proceed roughly along the lines of the terrestrial planet formation. It starts with planetesimals that undergo runaway growth, followed by the slower oligarchic stage. Hypotheses do not predict a merger stage, due to the low probability of collisions between planetary embryos in the outer part of planetary systems. An additional difference is the composition of the , which in the case of giant planets form beyond the so-called and consist mainly of ice—the ice to rock ratio is about 4 to 1. This enhances the mass of planetesimals fourfold. However, the minimum mass nebula capable of terrestrial planet formation can only form cores at the distance of Jupiter (5 AU) within 10 million years. The latter number represents the average lifetime of gaseous disks around sun-like stars. The proposed solutions include enhanced mass of the disk—a tenfold increase would suffice; protoplanet migration, which allows the embryo to accrete more planetesimals; and finally accretion enhancement due to in the gaseous envelopes of the embryos. Some combination of the above-mentioned ideas may explain the formation of the cores of gas giant planets such as and perhaps even . The formation of planets like and is more problematic, since no theory has been capable of providing for the in situ formation of their cores at the distance of 20–30 AU from the central star. One hypothesis is that they initially accreted in the Jupiter-Saturn region, then were scattered and migrated to their present location.

Visit now to discover an exhuastive list of idioms: avogadro's hypothesis, Glacial theory ∨ hypothesis, Nebular hypothesis, planetesimal hypothesis

Giant planet core formation is thought to proceed roughly along the lines of the terrestrial planet formation. It starts with planetesimals that undergo runaway growth, followed by the slower oligarchic stage. Hypotheses do not predict a merger stage, due to the low probability of collisions between planetary embryos in the outer part of planetary systems. An additional difference is the composition of the s, which in the case of giant planets form beyond the so-called and consist mainly of ice—the ice to rock ratio is about 4 to 1. This enhances the mass of planetesimals fourfold. However, the minimum mass nebula capable of terrestrial planet formation can only form cores at the distance of Jupiter (5 AU) within 10 million years. The latter number represents the average lifetime of gaseous disks around Sun-like stars. The proposed solutions include enhanced mass of the disk—a tenfold increase would suffice; protoplanet migration, which allows the embryo to accrete more planetesimals; and finally accretion enhancement due to in the gaseous envelopes of the embryos. Some combination of the above-mentioned ideas may explain the formation of the cores of gas giant planets such as and perhaps even . The formation of planets like and is more problematic, since no theory has been capable of providing for the in situ formation of their cores at the distance of 20–30 AU from the central star. One hypothesis is that they initially accreted in the Jupiter-Saturn region, then were scattered and migrated to their present location. Another possible solution is the growth of the cores of the giant planets via . In pebble accretion objects between a cm and a meter in diameter falling toward a massive body are slowed enough by gas drag for them to spiral toward it and be accreted. Growth via pebble accretion may be as much as 1000 times faster than by the accretion of planesimals.