"On the Measurement of Vorticity in Astrophysical Fluids" 

Steven Spangler; Professor emeritus of Physics and Astronomy, University of Iowa

Vorticity is the "swirliness" of a fluid, technically defined as the curl of the velocity field. Since plasmas are fluids, vorticity is an important concept in plasma physics as well. Vorticity is important in the understanding of turbulence because turbulence can be envisioned as a tangled web of vortices of different sizes and intensities. It would seem impossible to measure vorticity remotely in an astrophysical fluid like the interstellar medium, but a recent report claims just such a measurement. I examine this possibility, with the goal of determining how credible astronomical vorticity measurements can be.