Zeeman effect measurements of magnetic field strengths in diffuse and molecular clouds have been accumulating over the last decade. There are now well over one hundred Zeeman effect measurements or sensitive upper limits. These measurements sample the cold neutral medium (21 cm HI), low density molecular cores (18 cm OH), and high density molecular cores (3 mm CN). Most recently, an OH Zeeman effect campaign has explored magnetic field strengths in the inter-core regions of GMCs. The goal of all of these measurements is to establish the role (or lack thereof) of magnetic fields in the formation of GMCs and in the star formation processes that occur within them. Results to date clearly point to the energetic importance of magnetic fields in all of these environments. But do magnetic fields largely control the star formation process, as ambipolar diffusion models suggest, or do fields play a secondary role, as suggested by turbulence-driven star formation models? In this talk, I will examine the observational data and its implications for star formation theory. Turbulence-driven models seem to be preferred, but the evidence is hardly conclusive.
December 16, 2011
11:00 am
Array Operations Center Auditorium
All NRAO employees are invited to attend via video, available in Charlottesville Room 230, Green Bank Room 137 and Tucson N525.
Local Host: Claire Chandler