A Holistic View of the Magnetic Field in the Eridanus/Orion Region

Abstract

We present observations of 21 cm emission-line Zeeman splitting at 217 positions in the Orion/Eridanus loop region and incorporate them with stellar polarization data in a partially successful attempt to develop a holistic interpretation of the magnetic field structure on small and large size scales. We develop the "paraboloidal model" to describe the idealized perturbation to ambient magnetic field lines expected for a worm/chimney structure. We compare the magnetic field data to this model and find fair agreement for part of the region. On the small scale of one of the molecular clouds, previous interpretations invoke a helical field; in contrast, our interpretation invokes the Eridanus shock and its interaction with dense molecular clouds, in which the observed reversal in the line-of-sight field occurs naturally.