Non-ideal MHD simulations of subcritical prestellar cores with non-equilibrium chemistry

Abstract

Non-ideal magnetohydrodynamic (MHD) effects are thought to be gravity's closest ally in overcoming the support of magnetic fields and in forming stars. Here, we modify the publicly available version of the adaptive mesh refinement code FLASH (Fryxell et al. 2000; Dubey et al. 2008) to include a detailed treatment of non-ideal MHD and study such effects in collapsing prestellar cores. We implement two very extended non-equilibrium chemical networks, the largest of which is comprised of $\sim$ 300 species and includes a detailed description of deuterium chemistry. The ambipolar-diffusion, Ohmic and Hall resistivities are then self-consistently calculated from the abundances of charged species. We present a series of 2-dimensional axisymmetric simulations where we vary the chemical model, cosmic-ray ionization rate, and grain distribution. We benchmark our implementation against ideal MHD simulations and previously-published results. We show that, at high densities ($n_{{\mathrm{H}}_2}>10^6\mathrm{c}{\mathrm{m}}^{-3}$), the ion that carries most of the perpendicular and parallel conductivities is not ${\mathrm{H}}_3^{+}$ as was previously thought, but is instead ${\mathrm{D}}_3^{+}$.

18 pages, 14 figures. Accepted for publication in MNRAS

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Cited by in corpus (8)

• Chemistry and dynamics of the prestellar core L1544
• Can we observe the ion-neutral drift velocity in prestellar cores?
• The initial magnetic criticality of prestellar cores
• On the limitations of H alpha luminosity as a star formation tracer in spatially resolved observations
• CO enhancement by magnetohydrodynamic waves; Striations in the Polaris Flare
• Differences in chemical evolution between isolated and embedded prestellar cores
• Insights into the first and second hydrostatic core stages from numerical simulations
• Protostellar disc structure and dynamics during star formation from cloud-scale initial conditions