2011/03/31 by Kazunari Iwasaki, Shu-ichiro Inutsuka, Toru Tsuribe
Engineering · Physics and Astronomy · #Boundary value problem #Fluid Dynamics Simulations and Interactions #Gravitation #Gravitational acceleration #Gravitational collapse #Gravitational instability #Instability #Laser-Plasma Interactions and Diagnostics #Pulsars and Gravitational Waves Research #Smoothed-particle hydrodynamics #Wavenumber #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/733/1/17
12 pages, 14 figures, to be published in the Astrophysical Journal
openalex publication_date 2011/04/27 · arxiv created 2011/05/02 · arxiv updated 2015/05/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate the gravitational fragmentation of expanding shells driven by H ii regions using the three-dimensional Lagrangian simulation codes based on the Riemann solver, called Godunov smoothed particle hydrodynamics. The ambient gas is assumed to be uniform. In order to attain high resolution to resolve the geometrically thin dense shell, we calculate not the whole but a part of the shell. We find that perturbations begin to grow earlier than predicted by linear analysis under the thin-shell approximation. The wavenumber of the most unstable mode is larger than that in the thin-shell linear analysis. The development of the gravitational instability is accompanied by the significant deformation of the contact discontinuity. These results are consistent with a linear analysis presented by Iwasaki et al. that have taken into account the density profile across the thickness and approximate shock and contact discontinuity boundary conditions. We derive useful analytic formulae for the fragment scale and the epoch when the gravitational instability begins to grow.