RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 02 November 2017, 11:00-12:00; Duffield Lecture Theatre

Sven Buder

"The GALAH survey and Gaia"

In April 2018, the second Data Release of the ESA Gaia mission is expected and will once again broaden our astrometrical horizon. The week before, the team of the stellar spectroscopic Galactic Archaeology with HERMES (GALAH) survey will also publish its second Data Release, containing stellar parameters and up to 30 element abundances - in simple words: ’stellar DNA’ - for an unprecedented number of stars overlapping with Gaia, hence broadening the chemo-dynamic horizon by several magnitudes and dimensions. To accomplish this, the GALAH team is using a multi-step approach of a ’physics-driven’ spectrum analysis for a representative set of stars within the GALAH survey followed by the ’data-driven’ analysis with The Cannon. We construct (’train’) a spectral model of GALAH spectra based on the training set and then propagate the information onto the whole sample of currently more than 500 000 spectra. I will explain the machinery to achieve this in more detail and show first science results of the combination of GALAH and Gaia Data Release 1 - which can help you to get ready for GALAH & Gaia DR2 - including a sneak peak of GALAH DR2 element abundances covering various nucleosynthesis channels like alpha- and s-/r-process.