Four years ago, Anna Frebel, a young astronomer at the Massachusetts Institute of Technology, found an ancient star in a neighboring galaxy whose chemical composition proved nearly identical to some unusual stars on the outskirts of our own galaxy, which are older than the Milky Way itself.
It was a striking discovery, suggesting that the relatively young Milky Way is growing by conquest — “cannibalizing” nearby older dwarf galaxies. And it underscored the importance of a new way of learning how the universe evolved from the Big Bang to the modern cosmos.
Traditionally, astronomers study the early universe by looking back in time — peering deeper and deeper into space for vestiges of light from billions of years ago. But in the last decade, Dr. Frebel and others have used powerful telescopes and high-resolution spectroscopes to study the chemical composition of very old stars closer to home, in the Milky Way’s halo, producing a wealth of information about the creation of elements and the formation of the first stars and galaxies.
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