The Milky Way's First Light

The ancient Milky Way abounded with stars a few times more massive than the
Sun, say astronomers in Italy and the United States. These stars left their
mark by showering their stellar companions with carbon, barium, and other
elements. This is "the first direct observational evidence that the IMF
[initial mass function] of stars is not universal over time," the
astronomers say.

The full story is at http://KenCroswell.com/MilkyWayFirstLight.html