S21A0098

It is necessary to consistently interpret the near and far stellar halo populations to understand the accretion history of the Milky Way. LMS-1 is a kinematic substructure recently found at heliocentric distance of ∼ 20 kpc. Although it is suggested to be a disrupted low-mass dwarf galaxy that is independent from other known kinematic substructures, its kinematics is similar to the nearby stellar stream, the Helmi stream. We here propose to observe ∼ 15 stars in LMS-1 to clarify the connection between the two streams. Since our very recent results show that the Helmi stream has different α-element abundance trends with metallicity compared to other halo populations, chemical abundance ratios to be measured from the proposed observation will enable us to investigate the connection. Once the connection is confirmed, it advances our understanding of the spatial extent of the Helmi stream, which will open a novel window to constrain the property of the accretion event of its progenitor. On the other hand, it otherwise allows us to chemically characterize a disrupted low-mass dwarf galaxy. Since many of such systems are yet to be found and studied, our observation is, in any case, going to offer an unique opportunity toward the understanding of the Milky Way halo.

This document was translated from L^AT_EX by H^EV^EA.