Spin-orbit
coupling in magnetic systems
€The two stars in Polar systems rotate synchronously with
the orbit by the magnetic interactions, except in the case
of 4 systems which deviate slightly from synchronism
€Intermediate Polar systems are not synchronised
€Many IPs are found to have
Pspin~0.1Porb
due to field/stream interactions
€As the binary evolves and the period decreases it is likely that some IPs evolve into Polars
Norton, Somerscales & Wynn (2003)