The red clump giants are potentially very useful as standard candles.
There is some controversy about the stability of their I-band absolute
magnitude, but it does not seem to be serious. No controversy was ant
icipated about their colors, with metal rich giants expected to be red
der and cooler than the metal poor giants. The purpose of this paper i
s to point out that no such correlation is apparent between [Fe/H] and
T-eff as determined with Washington CCD photometry for the giants in
Baade's Window. No explanation is offered for this surprising result.
It is also unknown why the Galactic bulge red clump giants are redder
than the clump giants near the Sun by 0.2 mag in the (V - I)(0) color.