S18B0077abst
S18B0077
As a continuation of our previous observation S17B-105, we propose the second Keck/DEIMOS follow-up spectroscopy of a new Milky Way satellite, Cetus III, discovered in the HSC survey. In the previous observation, we have successfully obtained line-of-sight velocities and metallicities for a subset of candidate member stars. In this proposal, we observe the same targets as the previous run and also additional targets that were in the vignetting region of the DEIMOS mask in the previous run. The new spectroscopy will enable us to (1) measure line-of-sight velocity and a dispersion in Cetus III through increased genuine member stars and (2) examine whether some of them belong to binary systems. The latter is essential to accurately estimate dark matter content in this satellite. We will further measure metallicity of the member stars to asses the chemodynamical properties of this satellite. The proposed observation is essential to better understand the nature of faint satellites at the remote halo of the Milky Way Galaxy and its implications on the formation mechanism of the first galaxies in the early Universe.
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