Editing Planetary migration (section)

==Resonance capture==
The migration of planets can lead to planets being captured in resonances and chains of resonances if their orbits converge. The orbits of the planets can converge if the migration of the inner planet is halted at the inner edge of the gas disk, resulting in a system of tightly orbiting inner planets;<ref name="Cossou_etal_2014">{{cite journal |last1=Cossou |first1=Cchristophe |last2=Raymond|first2=Sean N. |last3=Hersant |first3=Franck |last4=Pierens |first4=Arnaud |title=Hot super-Earths and giant planet cores from different migration histories |journal=Astronomy & Astrophysics |date=2014 |volume=569 |page=A56 |doi=10.1051/0004-6361/201424157 |arxiv=1407.6011 |bibcode=2014A&A...569A..56C|s2cid=118845477 }}</ref> or if migration is halted in a convergence zone where the torques driving Type&nbsp;I migration cancel, for example near the ice line, in a chain of more distant planets.<ref name="Cossou_etal_2013">{{cite journal |last1=Cossou |first1=C. |last2=Raymond |first2=S.N. |last3=Pierens |first3=A. |title=Convergence zones for Type&nbsp;I migration: An inward shift for multiple planet systems |journal=Astronomy & Astrophysics |date=2013 |volume=553 |page=L2 |doi=10.1051/0004-6361/201220853 |arxiv=1302.2627|bibcode=2013A&A...553L...2C|s2cid=67764633 }}</ref>

Gravitational encounters can also lead to the capture of planets with sizable eccentricities in resonances.<ref name="Raymond_etal_2008">{{cite journal |last1=Raymond |first1=Sean N. |last2=Barnes |first2=Rory |last3=Armitage |first3=Philip J. |last4=Gorelick |first4=Noel |title=Mean motion resonances from planet-planet scattering |journal=The Astrophysical Journal Letters |date=2008 |volume=687 |issue=2 |page=L107 |doi=10.1086/593301 |arxiv=0809.3449 |bibcode=2008ApJ...687L.107R|s2cid=13063710 }}</ref> In the [[grand tack hypothesis]] the migration of Jupiter is halted and reversed when it captured Saturn in an outer resonance.<ref name="Walsh_etal_2011">{{cite journal|last1=Walsh|first1=Kevin J. |last2=Morbidelli |first2=Alessandro |last3=Raymond |first3=Sean N. |last4=O'Brien |first4=David P. |last5=Mandell |first5=Avi M. |title=A low mass for Mars from Jupiter's early gas-driven migration |journal=Nature |date=2011 |volume=475 |issue=7355 |pages=206–209 |doi=10.1038/nature10201 |pmid=21642961 |arxiv=1201.5177 |bibcode=2011Natur.475..206W|s2cid=4431823 }}</ref> The halting of Jupiter's and Saturn's migration and the capture of Uranus and Neptune in further resonances may have prevented the formation of a compact system of super-earths similar to many of those found by Kepler.<ref>{{cite journal |last1=Izidoro |first1=André |last2=Raymond |first2=Sean N. |last3=Morbidelli |first3=Alessandro |last4=Hersant |first4=Franck |last5=Pierens |first5=Arnaud |title=Gas giant planets as dynamical barriers to inward-migrating super-Earths |journal=Astrophysical Journal Letters |date=2015 |volume=800 |issue=2 |page=L22 |doi=10.1088/2041-8205/800/2/L22 |arxiv=1501.06308 |bibcode=2015ApJ...800L..22I|s2cid=118380596 }}</ref> The outward migration of planets can also result in the capture of planetesimals in resonance with the outer planet; for example the [[resonant trans-Neptunian object]]s in the Kuiper belt.<ref name=Malhotra_1995>{{cite journal |last=Malhotra |first=Renu |title=The origin of Pluto's orbit: Implications for the Solar System beyond Neptune |journal=Astronomical Journal |date=1995 |volume=110 |page=420 |doi=10.1086/117532 |arxiv=astro-ph/9504036 |bibcode=1995AJ....110..420M |s2cid=10622344 }}</ref> 

Although planetary migration is expected to lead to systems with chains of resonant planets most exoplanets are not in resonances. The resonance chains can be disrupted by gravitational instabilities once the gas disk dissipates.<ref name="Izidoro_etal_2017">{{cite journal |last1=Izidoro |first1=Andre |last2=Ogihara |first2=Masahiro |last3=Raymond |first3=Sean N. |last4=Morbidelli |first4=Alessaandro |last5=Pierens |first5=Arnaud |last6=Bitsch |first6=Bertram |last7=Cossou |first7=Christophe |last8=Hersant |first8=Franck |title=Breaking the Chains: Hot Super-Earth systems from migration and disruption of compact resonant chains |arxiv=1703.03634 |date=2017 |doi=10.1093/mnras/stx1232 |volume=470 |issue=2 |journal=Monthly Notices of the Royal Astronomical Society |pages=1750–1770 |doi-access=free |bibcode=2017MNRAS.470.1750I|s2cid=119493483 }}</ref> Interactions with leftover planetesimals can break resonances of low mass planets leaving them in orbits slightly outside the resonance.<ref name="Chatterjee_Ford_2015">{{cite journal |last1=Chatterjee |first1=Sourav |last2=Ford |first2=Eric B. |title=Planetesimal interactions can explain the mysterious period ratios of small near-resonant planets |journal=The Astrophysical Journal |date=2015 |volume=803 |issue=1 |page=33 |doi=10.1088/0004-637X/803/1/33 |arxiv=1406.0521 |bibcode=2015ApJ...803...33C|s2cid=118411464 }}</ref> Tidal interactions with the star, turbulence in the disk, and interactions with the wake of another planet could also disrupt resonances.<ref name="Baruteau_etal_2014">{{cite book |last1=Baruteau |first1=C. |last2=Crida |first2=A. |last3=Paardekooper |first3=S.-M. |last4=Masset |first4=F. |last5=Guilet |first5=J. |last6=Bitsch |first6=B. |last7=Nelson |first7=R. |last8=Kley |first8=W. |last9=Papaloizou |first9=J. |title=Protostars and Planets VI |chapter=Planet-Disk Interactions and Early Evolution of Planetary Systems |arxiv=1312.4293 |date=2014 |publisher=University of Arizona Press |pages=667–689 |bibcode=2014prpl.conf..667B |doi=10.2458/azu_uapress_9780816531240-ch029|isbn=9780816531240 |s2cid=67790867 }}</ref> Resonance capture might be avoided for planets smaller than Neptune with eccentric orbits.<ref name="Pan_Schlichting_2017">{{cite arXiv |last1=Pan |first1=Margaret |last2=Schlichting |first2=Hilke E. |title=Avoiding resonance capture in multi-planet extrasolar systems |date=2017 |eprint=1704.07836|class=astro-ph.EP }}</ref>