Galactic archaeology with asteroseismology: from oscillations to the evolution of the Milky Way

[摘要] Determining precise ages is one of the most limiting factors in accurately characterising the formation history of the Milky Way. Currentuncertainties of order > 40% render age estimates meaningless for stars older than 10 Gyr. It is anticipated that the major Galactic structures formed within the first few Gyr of the Milky Way's history, hence a higher temporal resolution is necessary to study this epoch. In this thesis, we present a series of results aimed at progressing the accuracy to which ages can be determined through asteroseismology. We introduce a new stellar parameter determination code, which can use oscillation mode frequencies as inputs. We show the code performs to expectation from the literature and that including the oscillation modes improves the accuracy and precision of the parameter determinations compared to existing methods. Ensemble asteroseismic grid modelling is applied to the K2 Campaign 3 and 6 fields. We find evidence for a bimodal age distribution for populations extending vertically within the Galactic disc, indicating multiple star formation epochs. Improvements in age resolution are still required to confirm any quiescence between distribution peaks. Increasing observational baselines and using individual mode frequencies may hold the key to achieving the temporal resolution required.

[发布机构] University:University of Birmingham;Department:School of Physics and Astronomy

[关键词] Q Science;QB Astronomy