Figure 5.14: The HR diagram in the δ Sct region, showing as a background all stars
with parallax accuracies better than 5 per cent. The known or suspected δ Sct stars
are indicated by circles, the SX Phe-like stars by asterisks. All periodic variables
with B − V between 0.1 and 0.5 are indicate with + signs. The colours of the
symbols indicate the amplitudes of the variations, from low (blue, typically around
0.02 mag.) to red (high, typically around 1.0 mag.)