http://www.newsweek.com/turns-out-were-living-zombie-galaxy-1088220

Our galaxy has “died” once before and we are now in its second life, according to a hypothesis put forward by a Japanese researcher.

In much of the Milky Way, the stars can be divided into two groups. Stars in the first group are rich in so-called “alpha” elements such as oxygen, magnesium and silicon, while those in the other are abundant in iron.