  Because of the unquestionable presence of magnetic fields in stars, their
role in the structure of stellar atmospheres has for a long time been a subject
of speculation. In our contribution to this discussion we present
spectropolarimetric evidence of the decrease of the radial component of the
magnetic field with altitude in the atmosphere of HD58260, a B-type magnetic
star on the main sequence. We show that the Stokes V profiles of metal lines in
emission of the outer atmosphere are evidence for a field three times weaker
than from absorption lines from inner layers. The extra flow of energetic
particles due to the magnetic-gradient pumping mechanism could be at the origin
of the magnetospheres surrounding this class of stars and at the basis of the
high energy phenomena observed. We also list a series of spectral lines useful
for measuring the surface field of early-type stars.
