EVIDENCE FOR MAGNETIC-FIELD-INDUCED ANISOTROPY OF THE INTERSTELLAR-MEDIUM

TURBULENCE in the interstellar medium transfers energy from parsec-siz ed regions to much smaller scales, and may be responsible for supporti ng clouds against gravitational collapse(1). Fluctuations in the elect ron density, which trace turbulence, occur on scales ranging from 10(6 ) to > 10(13) cm-the largest range of spatial scales seen in natural t urbulence. Despite almost thirty years of study, however, the causes a nd effects of interstellar turbulence are still poorly understood. Her e we present observations of OH masers in the Galactic star-forming co mplex W49N, which we use as point sources to investigate scattering al ong the line of sight. The masers' images are elliptical, and aligned roughly perpendicular to the Galactic plane. This alignment suggests t hat the magnetic field of our Galaxy influences interstellar turbulenc e(2,3) by mediating the transfer of energy from large to small spatial scales.