We present a new abundance analysis of HD 55496 , previously known as a metal-poor barium star .
We found that HD 55496 has a metallicity [ Fe/H ] = -1.55 and is s-process enriched .
We find that HD 55496 presents four chemical peculiarities : ( i ) a Na-O abundance anti-correlation ; ( ii ) it is aluminum rich ; ( iii ) it is carbon poor for a s-process enriched star and ( iv ) the heavy 2 ^ { nd } s-process peak elements , such as Ba , La , Ce , and Nd , present smaller abundances than the lighter s-process elements , such as Sr , Y and Zr , which is not usually observed among the chemically-peculiar binary stars at this metallicity .
The heavy-element abundance pattern suggests that the main source of the neutrons is the ^ { 22 } Ne ( \alpha , n ) ^ { 25 } Mg reaction .
Taken all these abundance evidence together into consideration , this strongly suggests that HD 55496 is a ‘ ‘ second generation of globular cluster star ’ ’ formed from gas already strongly enriched in s-process elements and now is a field halo object .
Our dynamical analysis , however , indicates that the past encounter probabilities with the known globular clusters is very small ( \leq 6 \% ) .
This evidence , together with the fact of having a retrograde motion , points to a halo intruder possibly originated from the tidal disruption of a dwarf galaxy .