  We present 23 Doppler images of the spotted RS CVn star HR 1099 from 1981 to
1992. HR 1099 shows a large cool polar spot which has persisted for the 11
years of this study and other low-latitude spots which come and go on
relatively short timescales. The polar spot has variable protuberances which
look very similar to the time-variable vertical extensions of the Sun's polar
coronal hole. The area of the polar spot and its extensions shows marginal
evidence of being periodically variable in time with a period of ~3 years. On
several occasions, isolated prominent spots emerged and then disappeared near
the equator. The tracks of two long-lived spots suggest that some spots which
emerge at low or intermediate latitudes migrate up to the pole in a clockwise
spiral (slower than the orbit), and then apparently merge with the polar spot.
Differential rotation as measured from spot movements showed that intermediate
and low latitudes rotate slightly slower than the orbital angular velocity,
while the pole and highest latitudes appear to be synchronized to the orbit.
The differential rotation is of opposite sign and a factor of 50 less than for
the Sun. We propose that the starspots on HR 1099 and other rapidly rotating RS
CVn stars are, by analogy with solar coronal holes, large unipolar magnetic
regions tightly frozen into multi-kilogauss axisymmetric dipole fields in these
stars. Since the large cool polar spots, the signature of these dipoles, are
not present on more slowly rotating RS CVn stars, we believe that they must be
dynamo-induced rather than remnant fossil fields.
