The Magnetic Field in the Local Bubble Wall towards l,b∼300,0.

Magnetic fields are thought to play important roles in many areas of interstellar medium dynamics by providing pressure terms as well as resisting the flow of charged particles across field lines. Observationally probably the easiest tracer of the magnetic field is the interstellar polarization, induced by asymmetric dust grains aligned with the magnetic field. Using the well-known Chadrasekhar-Fermi method we can use the dispersion in the polarization angles to derive an estimate of the plane-of-the-sky field component. Complementary measurements of Zeeman splitting in the H I or OH lines, or Faraday rotation of the emission from a background radio source, can provide the line-of-sight component. Here we use polarization of a set of stars with known distances to estimate a magnetic field strength in the wall of the Local Bubble, in a region towards l,b∼(300,0), of ∼8 μG, equivalent to a thermal pressure of ∼18,000 K cm-3. As the bubble wall likely constitutes swept-up material, we argue that this plane-of-the-sky field is fully consistent with a weak, or non-detected, line-of-sight field. [ABSTRACT FROM AUTHOR]