3.4. Fine structure of the field
M31 was also observed at
20 cm with the VLA
with 45" (150 pc) resolution
(Beck et al., 1998).
The total continuum emission
shows remarkable asymmetries: The ring is thin (full
half-power width of 300-400 pc) in the
northeastern (Fig. 4a) and southwestern
quadrants, but thick (width of 700-1000 pc) in the northwestern and
southeastern (Fig. 4b) quadrants. The latter
quadrant shows several filaments perpendicular to the ring.
 |
 |
Figure 4. Total intensity at
|
The highest resolution (15" or 50 pc) so far was obtained with the
VLA at 6 cm in a
portion of the southwestern ring
(Hoernes, 1997).
The polarization vectors show systematic fluctuations around the mean
orientation, according to
Beck et al. (1989)
possibly signatures of
Parker instabilities. The fine structure of the irregular field
is partly resolved. The largest scale of the turbulent field is
about 50 pc, in agreement with results from the Galaxy (e.g.
Rand & Kulkarni, 1989).