Serpens Caput constellation. Optical image of the constellation Serpens Caput. Serpens is a constellation of the northern hemisphere. It is split into two non-contiguous parts, Serpens Caput (Serpent Head) to the west and Serpens Cauda (Serpent Tail) to the east. Between these two halves lies the constellation of Ophiuchus, the Serpent-Bearer. The brightest star in Serpens Caput is the red giant star Alpha Serpentis, or Unukalhai.