Using a technique called spectroscopy, they were able to see that the light shining from the galaxy's edges seemed to come from very hot sources rich in helium but essentially devoid of heavier elements.

利用名为“光谱学”的技术，他们发现从星系边缘发出的光，似乎来自非常热的光源，而这个光源富含氦元素但基本上不含重元素。