Ken Freeman is hunting for fossils. But he’s not looking for old bones—he’s exploring the very origin and history of our Milky Way galaxy.
Conventional theory says that our galaxy grew big by engulfing smaller ones. If this is correct, stars from the original galaxies should be still identifiable within the main mass of stars via several tell-tale signs, from unusual velocities to spectral types. These stellar fossils would point to the galaxy’s birth and growth.
Ken, an astronomy professor at the Australian National University (ANU), along with Joss Bland-Hawthorn of the University of Sydney, pioneered the field of galactic archaeology. “Galactic archaeologists are aiming to discover and interpret the stellar fossil record, so that we can get a strong observational basis for our ideas about how galaxies like the Milky Way formed,” says Ken. Doubts linger, however, about whether or not the big-from-small theory is fully correct.
“The theoretical models have great trouble in generating a galaxy shaped like ours,” Ken says. Observations using Australian facilities and instruments could settle the question. The ANU’s new SkyMapper telescope will help select stars for study, and the Australian Astronomical Observatory’s (AAO’s) AAOmega instrument will provide spectral information on these target stars.
The main work, though, will come from the AAO’s High Resolution Multi-Object Spectrometer (HERMES) which, when commissioned in late 2012, will make detailed measurements of the velocity, chemistry and temperature of about a million stars in the hunt for fossils. The HERMES results should begin to emerge around 2015.