Discovery of Peculiar Double-Mode Pulsations and Period Doubling in   KEPLER RRc Variables
  We analyzed the Long Cadence photometry of 4 first overtone RR Lyr-type stars (RRc stars) observed by the KEPLER telescope. All studied variables are multiperiodic. The strongest secondary peak appears for f_2/f_1 = 1.58-1.63, or P_2/P_1 = 0.61-0.63. In each star we detect at least one subharmonic of f_2, either at ~1/2 f_2 or at ~3/2 f_2. The presence of subharmonics is a characteristic signature of a period doubling. 
P. Moskalik, R. Smolec, K. Kolenberg, J. Nemec, A. Kunder, M. Chadid,   G. Kopacki, R. Szab\'o and KEPLER WG#13 members
astro-ph.SR