主星系 meaning in English

dominant galaxy

X - rays from chandra ( colored purple ) , optical and ultraviolet ( uv ) data from hubble ( red and orange ) , and radio emission from the very large array ( vla ) and merlin ( blue ) show how the jet from the main galaxy on the lower left is striking its companion galaxy to the upper right
钱德拉（紫色部分）的x射线，哈勃(红色和橙色部分）的光学和紫外线，以及vla和merlin射电图像显示在图左下方的主星系发出的喷流正击中乐在右上方的伴星系。