SDSS J1229+1122
SDSS J1229+1122 (SDSS J122952.66+112227.8) is a blue supergiant O-type star in the tail of dwarf irregular galaxy IC 3418. It illuminates a nebula clump of gas, and was discovered from the spectrum of the illumination source. The clump of gas lives in a tail caused by ram pressure stripping of gas from the galaxy by the galaxy cluster. It was decided to be a blue supergiant through analysis of its spectrum.