The role and importance of magnetic fields in the star formation process
remains controversial. The most important observable parameter that could
resolve this controversy is the mass to magnetic flux ratio, which is
proportional to the ratio of column density to magnetic field
strength. Magnetic field strengths in the interstellar medium and in
molecular clouds have been measured by detection of the Zeeman effect in
radio-frequency lines of H I, OH, H2O, and CN. Statistical
estimates of field strengths have also been made from the dispersion in
position angles of linearly polarized dust emission and absorption. In this
talk I will review the current state of the observational data on magnetic
field strengths and on mass to flux ratios as functions of the volume
density of hydrogen in atomic and molecular clouds and discuss the
implications of these results for understanding the role of magnetic fields
in star formation. I will also briefly discuss future prospects for
resolving the controversial issue of whether magnetic fields are a
significant player in the star formation process.
To begin viewing slides, click on the first slide below. (Or, view as pdf.)