3.2.2 Coronal active regions where the magnetic field is closed. This gives kg m and pascals. Thus, is small in the corona.
Coronal holes have a weaker magnetic field strength and a lower temperature.
Typically we take Thus, in a coronal hole the plasma beta has a typical value of and is even smaller than the active region value. To a good approximation the magnetic field in the solar corona is force-free since the plasma beta is much smaller than unity. This is not the case in the convection zone where the plasm beta is usually much larger than unity. The next few sections will consider different force free equilibria. Hydrostatic Pressure Balance Prof.