T. Foglizzo et M. Tagger, THE PARKER-SHEARING INSTABILITY IN AZIMUTHALLY MAGNETIZED DISCS, Astrophysical letters & communications, 34(1-6), 1996, pp. 351-356
Using a linear analysis, in the framework of the shearing sheet approx
imation, we have investigated the stability of a differentially rotati
ng, stratified gaseous disc embedded in a purely azimuthal magnetic fi
eld. We show that a realistic differential rotation is strong enough t
o couple the different waves, and allows, in particular, an efficient
coupling of the Parker mode with spiral density waves. Perturbations w
ith a vertical wavelength much smaller than the scaleheight of the dis
c are subject to the shearing instability. We describe its mechanism i
n detail, and its interplay with the Parker instability when the verti
cal stratification is taken into account.