We present the first detailed abundance analysis of the metal-poor giant HKII 17435-00532 .
This star was observed as part of the University of Texas long-term project Chemical Abundances of Stars in the Halo ( CASH ) .
A spectrum was obtained with the High Resolution Spectrograph ( HRS ) on the Hobby-Eberly Telescope with a resolving power of R \sim 15 , 000 .
Our analysis reveals that this star may be located on the red giant branch , red horizontal branch , or early asymptotic giant branch .
We find that this metal-poor ( [ Fe/H ] = -2.2 ) star has an unusually high lithium abundance ( \log \varepsilon ( Li ) = +2.1 ) , mild carbon ( [ C/Fe ] = +0.7 ) and sodium ( [ Na/Fe ] = +0.6 ) enhancement , as well as enhancement of both s -process ( [ Ba/Fe ] = +0.8 ) and r -process ( [ Eu/Fe ] = +0.5 ) material .
The high Li abundance can be explained by self-enrichment through extra mixing that connects the convective envelope with the outer regions of the H-burning shell .
If so , HKII 17435-00532 is the most metal-poor star in which this short-lived phase of Li enrichment has been observed .
The Na and n -capture enrichment can be explained by mass transfer from a companion that passed through the thermally-pulsing AGB phase of evolution with only a small initial enrichment of r -process material present in the birth cloud .
Despite the current non-detection of radial velocity variations ( over \sim 180 days ) , it is possible that HKII 17435-00532 is in a long-period or highly-inclined binary system , similar to other stars with similar n -capture enrichment patterns .