Low States and Outbursts
Some IPs have shown occasional low states in archival plate photometry,
but probably not as frequently as in AM Her type systems. What are
they caused by, is it X-ray irradiation? IPs have stronger hard X-rays
but the accretion disk would shield the secondary...
Several IPs have shown occasional, very short, outbursts. Several lines
of evidence points to these being episodes of enhanced accretion rate
from the secondary.
GK Per, an anomalous system in many respects, has very long outbursts,
possibly related to the long orbital period of this system.
References