The Self-Similarity of Shear-dominated Viscous Stirring
Author(s) -
Benjamin F. Collins,
Hilke E. Schlichting,
Re’em Sari
Publication year - 2007
Publication title -
the astronomical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.61
H-Index - 271
eISSN - 1538-3881
pISSN - 0004-6256
DOI - 10.1086/513718
Subject(s) - eccentricity (behavior) , planetesimal , classical mechanics , physics , self similarity , population , shearing (physics) , mechanics , statistical physics , distribution function , boltzmann equation , distribution (mathematics) , mathematical analysis , geometry , mathematics , planet , astrophysics , quantum mechanics , demography , sociology , political science , law , thermodynamics
We examine the growth of eccentricities of a population of particles withinitially circular orbits around a central massive body. Successive encountersbetween pairs of particles increase the eccentricities in the disk on average.As long as the epicyclic motions of the particles are small compared to theshearing motion between Keplerian orbits, there is no preferred scale for theeccentricities. The simplification due to this self-similarity allows us tofind an analytic form for the distribution function; full numericalintegrations of a disk with 200 planetesimals verify our analyticalself-similar distribution. The shape of this non-equilibrium profile isidentical to the equilibrium profile of a shear-dominated population whosemutual excitations are balanced by dynamical friction or Epstein gas drag.Comment: 8 pages, 2 figure
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