Moving mesh simulations of star forming cores in magneto-gravo-turbulence

Philip Mocz (Harvard CfA) - November 21, 2016 at 12:10 pm

Star formation occurs in midst of a contest between self-gravity, turbulent pressure, and the magnetic field. In this talk, I will discuss the role of the magnetic field and under what conditions the cloud cores that form inherit large-scale field morphologies or are governed by cloud turbulence. I describe a new moving mesh constrained transport numerical method to solve the magnetohydrodynamics equations. The moving mesh allows simulations to resolve gravitational collapse over orders of magnitude in dynamic range. I will present a range of simulations of parsec scale supersonic, turbulent molecular clouds, self-consistently resolving star formation down to a few AU scales (relevant for future ALMA observations). Core properties are found to be largely independent of the mean-field strength in the cloud, as long as turbulent pressure dominates the magnetic pressure. In this regime, collapse is approximately isotropic with B proportional to rho^(2/3) due to flux freezing, with turbulent field morphology uncorrelated with the large-scale field. In the strongly magnetized case, collapse is anisotropic with B proportional to rho^(1/2) and the field has a simple hourglass morphology aligned with the large-scale field. Different observations suggest that star formation in the interstellar medium may be occurring in both regimes.

The seminar will be held in 131A Campbell Hall.

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