Key points are not available for this paper at this time.
Context.The metal-rich bulge globular cluster NGC 6441 shows both a well-developed blue horizontal branch (Rich et al.), and a strong slope upward from the red clump to the blue of the RR Lyrae region. The former corresponds to the well–known second parameter problem. Both features are not explained by conventional evolutionary models.
Caloi et al. (Mon,) studied this question.