S20A0121abst
S20A0121
We propose a research program aiming at addressing one of the fundamental questions in the chemical evolution of the Milky Way: do stars migrate radially in the Galactic disk? This is a critical question because, if true, radial migration determines the fate of the Galactic chemical evolution, revolutionising our perception of the origin of the Solar system. We will confront with this quintessential question by a GMOS spectroscopic (0.36–0.92 µm) survey of 162 planetary nebulae (PNe) in the Galactic disk, augmented with the archival VLT/Keck/Subaru UV-optical spectra of additional 68 PNe. Our data set will determine the [O/Ne/S/Cl/Ar] gradients at <∼1, ∼4–6, and >∼8 Gyr ago with with improved PN distance scales delivered by gaia. In this semester, we observe 31 young-age (<∼1 Gyr) PNe in order to (1) establish the metallicity gradient at <∼1 Gyr ago and (2) verify the flattening metallicity gradient from ∼4–6 Gyr to <∼1 Gyr ago found even in our research based on the archived data. If the flattening gradient from ∼4–6 Gyr to <∼1 Gyr is true, we will have to identify physical processes other than radial migration in order to explain the observational data. Thus, this proposed observation is important in order to determine the future direction of the study on Galaxy chemical evolution.
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