UChicago News reports:

Not all archaeologists study ancient pottery and arrowheads. If you’re a stellar archeologist, you seek the oldest stars in the universe—those born long before our own sun and planet came into being.

A group led by University of Chicago scientists has discovered a star that appears to date back to the second generation of stars ever formed. Still inside the tiny primordial galaxy where it was first born, it has a unique elemental makeup that can tell us about these early days of the universe—as well as how most of our periodic table came to exist.

“This is the first really clear detection of which elements are initially produced in primordial galaxies,” said Anirudh Chiti, the first author of the study, a postdoctoral researcher at UChicago at the time of the work and now at Stanford University. “It’s a nice missing piece of the puzzle about how elements were formed back in those early days.”

The study is published March 16 in Nature Astronomy.

Hunting for the most ancient stars

In those early days after the Big Bang, the universe was a lot less interesting than it is now.

There were stars, but they were all the same kind of massive star made of three elements—hydrogen, helium and lithium—because those were the only elements that existed. You wouldn’t be able to find any of the calcium, gold or other elements that make up our world today, because those elements first had to be forged inside the stars themselves.

In the hearts of these massive stars, atoms were fusing to become increasingly heavy elements. When those stars exploded at the end of their lives, new stars formed from the debris, and the process happened over and over until we got the full range of elements that we know and love today.

Scientists have pieced together this broad outline from other evidence. But no one had yet been able to find a star from this period still in its original galaxy, which would help untangle remaining questions about this process of element formation. [Continue reading…]