Résumé :
There are currently two extreme-case theoretical paradigms for what drives
star formation: (1) magnetic support of molecular clouds against gravity
with ambipolar diffusion leading to core collapse, and (2) compressible
turbulence in the interstellar medium that sometimes produces
self-gravitating cores, which then collapse once turbulent support
dissipates. The fundamental difference between these paradigms is the role
of magnetic fields. I will describe specifically how observations of
magnetic field strengths and morphologies allow tests of these paradigms,
briefly review observational polarization techniques for studying magnetic
fields in star formation regions, and describe recent observational
results. The recent and previous results of observations of magnetic fields
in molecular clouds will then be used to apply the tests, and the results
for our understanding of the star formation process will be described.
