Grand Tack Hypothesis

Toggle the table of contents Grand tack hypothesis 14 languages العربيةDeutschEspañolSuomiFrançaisHrvatskiItaliano日本語한국어МакедонскиРусскийSimple EnglishTagalog中文 Edit links ArticleTalk English ReadEditView history Tools Tools move to sidebar hide Actions ReadEditView history General What links hereRelated changesUpload filePermanent linkPage informationCite this pageGet shortened URL Print/export Download as PDFPrintable version In other projects Wikidata item Appearance move to sidebar hide From Wikipedia, the free encyclopedia Theory of early changes in Jupiter's orbit Jupiter might have shaped the Solar System on its grand tack In planetary astronomy, the grand tack hypothesis proposes that Jupiter formed at a distance of 3.5 AU from the Sun, then migrated inward to 1.5 AU, before reversing course due to capturing Saturn in an orbital resonance, eventually halting near its current orbit at 5.2 AU. The reversal of Jupiter's planetary migration is likened to the path of a sailboat changing directions (tacking) as it travels against the wind.[1] The planetesimal disk is truncated at 1.0 AU by Jupiter's migration, limiting the material available to form Mars.[2] Jupiter twice crosses the asteroid belt, scattering asteroids outward then inward. The resulting asteroid belt has a small mass, a wide range of inclinations and eccentricities, and a population originating from both inside and outside Jupiter's original orbit.[3] Debris produced by collisions among planetesimals swept ahead of Jupiter may have driven an early generation of planets into the Sun.[4] Description[edit] In the grand tack hypothesis, Jupiter underwent a two-phase migration after its formation, migrating inward to 1.5 AU before reversing course and migrating outward. Jupiter's formation took place near the ice line, at roughly 3.5 AU. After clearing a gap in the gas disk Jupiter underwent type II migration, moving slowly toward the Sun with the gas disk. If uninterrupted, this migration would have left Jupiter in a close orbit around the Sun, similar to hot Jupiters in other planetary systems.[5] Saturn also migrated toward the Sun, but being smaller it migrated faster, undergoing either type I migration or runaway migration.[6] Saturn converged on Jupiter and was captured in a 2:3 mean-motion resonance with Jupiter during this migration. An overlapping gap in the gas disk then formed around Jupiter and Saturn,[7] altering the balance of forces on these planets which began migrating together. Saturn partially cleared its part of the gap reducing the torque exerted on Jupiter by the outer disk. The net torque on the planets then became positive, with the torques generated by the inner Lindblad resonances exceeding those from the outer disk, and the planets began to migrate outward.[8] The outward migration was able to continue because interactions between the planets allowed gas to stream through the gap.[9] The gas exchanged angular momentum with the planets during its passage, adding to the positive balance of torques, allowing the planets to migrate outward relative to the disk; the exchange also transferred mass from the outer disk to the inner disk.[10] The transfer of gas to the inner disk also slowed the reduction of the inner disk's mass relative to the outer disk as it accreted onto the Sun, which otherwise would weaken the inner torque, ending the giant planets' outward migration.[8][11] In the grand tack hypothesis this process is assumed to have reversed the…

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