Mark Morris
University of California, Los Angeles
HAWC+ Observations of the Magnetic Field in the Sickle
Explorations of Interface Instabilities Observations at 53 µm of polarized thermal dust emission from the region surrounding the Sickle HII region (G0.18-0.04) surrounding the Quintuplet Cluster in the Galactic center have been made with the HAWC+ far-IR polarimeter on SOFIA. The data provide abundant information on the geometry of the magnetic field on both sides of the ionization front at the interface with the molecular cloud. The magnetic field in the cloud is relatively uniform, and is predominantly parallel to the Galactic plane, as has long been known. However, the radiation field and the strong winds from the massive Quintuplet Cluster stars impact the cloud along two edge-on surfaces within which the magnetic field has very different orientations relative to the local directions of the incoming wind and radiation. Where the ambient cloud field is perpendicular to the incoming wind and radiation, the field is compressed and remains laminar, and the interface is dynamically stable. In contrast, where the magnetic field orientation within the cloud is parallel to the direction of the wind and radiation impacting the interface, the surface is unstable to forming corrugations that have evolved into the bright-rimmed pillars that have been observed there. The role of the magnetic field in damping or enhancing such instabilities according to the field orientation will be discussed.
