RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 30 July 2015, 11:00-12:00; Duffield Lecture Theatre

Louise Howes

"Final Thesis Talk"

Ladies and Gentlemen, I would like to bring to your attention a momentous occasion. The first SkyMapper Ph.D. is (almost) complete! I know some feared this day would never come; for many students have come before me, and SkyMapper thwarted all their plans. I hope you’ll all join me to celebrate SkyMapper’s achievement by coming to my Final Thesis Talk. I’ve spent the past 3.7 years searching for the oldest stars in the Milky Way, using SkyMapper photometry to hunt for metal-poor stars in the Galactic bulge. Cosmological simulations of galaxy formation predict that the very first stars formed at redshits z>15 in the largest overdensities, which over time grew into the central regions of large galaxies such as the Milky Way. The remnants of these oldest stars should be observable today as metal-poor stars on tightly bound orbits close to the Galactic centre. The EMBLA survey made use of SkyMapper’s unique filter system to hunt through more than 5 million stars in the Galactic bulge, picking out metal-poor candidates to observe using AAOmega/2dF at the AAT. Three years of observations and 14,000 stars later, and we’ve found at least 10 stars with [Fe/H]<-3, and using the latest OGLE astrometry, we have been able to confirm most of them lie on tightly bound objects. These could well be the oldest known objects in the Universe!