New spectroscopic analysis techniques for Galactic archaeology
Astronomy and astrophysics
Friday 27 March 2015
to 11:30 at
Karin Lind (Uppsala University)
The analysis of cool star spectra has a century-long successful history, but the recent explosion in the quality and quantity of spectra has made it clear to us that the state-of-the-art analysis do not do justice to the information content of the data and cannot extract stellar parameters and element abundances to the accuracy that the broader context requires. In particular, significant errors are caused by uncertain atomic and molecular data and the failures of the common assumptions of local thermodynamic equilibrium (LTE) and 1D hydrostatic geometry of the stellar atmospheres. In particular at low metallicities, departures from LTE are large and tend to amplify further using the more realistic temperature stratifications predicted by 3D hydrodynamical models. To successfully utilise these models in the era of large spectroscopic surveys challenges us to develop combined 3D+NLTE techniques that are still numerically feasible for very large samples. I will present efforts made in this direction.