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S20A0123abst

S20A0123

We propose to obtain high-resolution spectra with Subaru/HDS for 11 brighter members(G < 15) of the GD-1 stream confirmed by data from Gaia DR2, SDSS DR14 and LAMOST DR6. Its progenitor is confirmed by the previous study to be a globular cluster with [Fe/H] ∼ βˆ’2.3 and age of 13 Gyr (Li, Yanny & Wu 2018, ApJ, 869, 122), perhaps one of the most metal-poor globular clusters in the Milky Way. This program will determine the abundance patterns of Ξ± elements (O, Mg, Si, Ca, Ti), odd-Z elements(Na, Al), iron-peak (Sc, Cr, Ni, Mn) and the neutron capture elements (Y, Ba, Eu) to confirm the progenitor of GD-1 stream by measurement of chemical abundances. Such high-resolution abundance patterns and comparison with Galactic field stars, globular clusters and dwarf galaxies will reveal the formation mechanism and the evidence for multiple populations of the progenitor of the GD-1 stream, and may also lead to the discovery of the most metal-poor globular cluster in the Milky Way. This work will reveal not only the origin of the GD-1 stream, but the contribution of merging clusters to the formation of the metal-poor halo.

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