The photometric and high resolution spectroscopic study of a sample of RR
Lyrae which exhibit anomalous scatter and large amplitude
variations of their light curves is continuing,
in collaboration with Carretta and Gratton (Padova Obs.), Ivans
and Sneden (Univ. Texas), Marconi (Napoli Obs.), Smith (MSU), and
Wilhelm (Southwestern
Un.). The observational campaign
conducted with the 1.52m telescope in Loiano, the 60 cm of the Michigan
State University, the
40 cm of the Southwestern University, and
the 2.7 m telescope of the McDonald Observatory (for spectroscopy) has been
completed as well as the data reduction.
CM Leo has been found to be a very regular c-type RR Lyrae with metal
abundance [Fe/H]=-1.94
0.2. The photometric and radial velocity curves
of CM Leo have been compared with the prediction of convective pulsational
models getting an absolute magnitude M
=0.47. This value, once corrected
for evolutionary and metallicity effects, leads to a true distance modulus of
the Large Magellanic Cloud of 
=18.43 mag.