Searching for the oldest stars

Presented by ANU College of Science

Take a walk on a moonless night. Watch the Milky Way above, made from a myriad of stars. Did you know that some of them have been shining for more than 13 billion years? These are the oldest, still surviving, objects in our 13.8 billion years old universe. "Stellar archaeology" identifies these extremely rare relics. Analysis of their chemical composition shows that they contain only trace amounts of heavy elements (e.g. calcium, iron) because these stars formed at a time when little of these elements existed. This offers the extraordinary opportunity to use local Milky Way stars for exploring the earliest times in the universe.

This work has revealed tantalizing details about the short-lived very first stars which cannot be studied otherwise. When they exploded as supernovae they left behind individual element signatures in the surrounding gas clouds. These "chemical fingerprints" were incorporated into the next generation long-lived stars that we still observe today. Having access to these fingerprints also provides exclusive information about element nucleosynthesis, chemical evolution, early star and galaxy formation processes, and even the formation of the Milky Way.

Assistant Professor Anna Frebel offers an intriguing account of the latest research results paired with a unique insight into life as an astronomer. Having discovered several of the oldest and most primitive stars using the world's largest telescopes she tells fascinating discovery stories that allow the audience to witness what it means to be a scientist in this day and age.

Spectacular video clips about observing with the 6.5m optical Magellan telescopes in the Atacama Desert in Chile will also be shown.

Anna Frebel is Assistant Professor of Physics at the Massachusetts Institute of Technology (MIT). She has received numerous international honours and awards for her discoveries and subsequent chemical abundance analyses of the oldest stars and how these stars can be employed to uncover information about the early Universe some 13 billion years ago. Professor Frebel has authored more than 70 papers in various refereed journals, including Nature, and enjoys communicating science to the public through public lectures, magazine articles, interviews as well as her popular science book Searching for the oldest stars (available in English after mid-2015, by Princeton University Press).