Abstract The Large Sky-Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 3 provided 341 691 K giant stars with stellar parameters. Based on the models of Law & Majewski, we identified 252 K giant stars in the leading stream associated with the Sagittarius (Sgr) dwarf galaxy. We obtained 132 K giant stars belonging to the trailing arm of Sgr using the model of Belokurov et al. We studied the metallicity distribution of member stars along the streams and found a flat gradient in the first wrap of the leading stream, –(0.88±0.3) × 10 −3 dex/(°) in the second wrap of the leading stream and –(1.2±0.3) × 10−3 dex/(°) in the first wrap of the trailing stream. Moreover, we obtained a combined metallicity gradient with our sample and data from the literature. We also analyzed the properties of an overdensity, which is located in the leading stream of the Sgr.
Keywords Galaxy: halo — galaxies: individual (Sagittarius) — stars: K giant-branch
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