We show that SDSS J170733.93+585059.7 ( hereafter SDSS J1707+58 ) , previously identified by Aoki and collaborators as a carbon-enhanced metal-poor star ( with s-process-element enhancements ; CEMP-s ) , on the assumption that it is a main-sequence turn-off star , is the RR Lyrae star VIII-14 identified by the Lick Astrograph Survey .
Revised abundances for SDSS J1707+58 are [ Fe/H ] = –2.92 , [ C/Fe ] = +2.79 , and [ Ba/Fe ] = +2.83 .
It is thus one of the most metal-poor RR Lyrae stars known , and has more extreme [ C/Fe ] and [ Ba/Fe ] than the only other RR Lyrae star known to have a CEMP-s spectrum ( TY Gru ) .
Both stars are Oosterhoff II stars with prograde kinematics , in contrast to stars with [ C/Fe ] < +0.7 , such as KP Cyg and UY CrB , which are disk stars .
Twelve other RR Lyrae stars with [ C/Fe ] \geq + 0.7 are presented as CEMP candidates for further study .