Exploring Kinematic And Chemical Properties Of Stellar Streams

The stellar stream is a debris of dwarf galaxy or globular cluster that is de-formed,distegrated and torn apart by tidal force.As a significant composition of galactic halo,tidal stream is crucial for exploring the formation of the Milky Way.Based on stellar sepectroscopic data of SDSS and LMAOST,we characterize the kinematic and chemical properties of Sgr stream and VOD region to understand Lambda Cold Dark Matter and gravitational potential of the Milky Way.We used 1354 members of Sgr stream to compare distance and Vgsr of leading and trailing arm with obsevation and model theoretical models.The Vgsr of trailing arm is lower than LM10 and DL17.We find the VY and metallicity of trailing arm exhibit a trend along Z direction.We divide trailing arm into inner one and outer one depending on whether Z greater than-18 kpc.We summarize statistical data and get that the metallicity of RGBs in inner trailing arm is metal-richer than out trailing arm,but the metallicity of K giants stay the same.The two components of trailing arm have a clear boundary in Energy-Angular momentum plane.The energy of trailing arm is higher than leading arm.To avoid random fluctuations,we select fake groups with the same FoF method.We select 7 significant groups in VOD region by comparing 29 grousp with stan-dard result of model.The previous study indicates that group 1,2 and 5 are probably parts of perpendicular stream.VSS is also a part of perpendicular stream.We further analyse kinematic properties of perpendicular stream and Sgr stream and predict that group 4 is also a part of perpendicular stream.Af-fected by Sgr stream,group 4 deviate from its original orbit and move closer to galactic center.Finally,we judge that Feature C doesn't belong to Sgr stream because of short distance.