Figure 2. A color-color diagram which combines data from different catalogs and spectral regions.
The symbols represent the same groups of objects as in Fig. 1. A few open circles in the upper
right-hand corner represent normal K-type stars. Most of the M-type stars seen in Fig. 1 are out
of the range of Fig. 2. They have larger F_K/F₁₂ flux ratios. The dashed lines show empirical
boundaries between cool and hot stars with CS dust. All known dusty RV Tau stars are presented
in Figs. 1 and 2.