Surface imaging of long-period variable stars

The photospheric surfaces of five long-period variables (o Cet, R Leo, W Hya, χ Cyg and R Cas) have been imaged in the optical/near-IR with the 4.2-m William Herschel Telescope. All exhibit departures from circular symmetry. Our data are consistent with the presence of bright compact features, individually contributing between 5 and 20 per cent of the total stellar flux, on most of the stars. The characteristics and behaviour of the features are similar to those reported on the surfaces of late-type supergiants. However, the data presented here are inadequate to identify a common physical origin.