Two Portions of Sagittarius Stream in the LAMOST Complete Spectroscopic Survey of Pointing Area at Southern Galactic Cap

Abstract

We constructed a sample of 13,798 stars with $T{}_{\mathrm{eff}}$, log $g$, [Fe/H], radial velocity, proper motions and parallaxes from LAMOST DR5 and Gaia DR2 in the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) at the Southern Galactic Cap consisting of areas A and B. Using the distributions in both proper motions and radial velocity, we detected very significant overdensities in these two areas. These substructures most likely are portions of Sagittarius (Sgr) stream. With the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, 220 candidates stream members were identified. Based upon distance to the Sun and published models, 106 of these stars are likely to be the members of the Sgr stream. The abundance pattern of these members using [$\alpha$/Fe] from Xiang et al. were found to be similar to Galactic field stars with [Fe/H] $<$ -1.5 and deficient to Milky Way populations at similar metallicities with [Fe/H] $>$ -1.0. No vertical and only small radial gradients in metallicity along the orbit of Sgr stream were found in our Sgr stream candidates.

ApJ in press

References in corpus (14)

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• An all-sky proper motion map of the Sagittarius stream using Gaia DR2
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• Full 5D characterisation of the Sagittarius stream with Gaia DR2 RR Lyrae
• Identifying Sagittarius Stream Stars By Their APOGEE Chemical Abundance Signatures
• Tracing Kinematic and Chemical Properties of Sagittarius Stream by K-Giants, M-Giants, and BHB stars
• The LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap I. The Spectroscopic Redshift Catalog

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• Existence of Tidal Tails for the Globular Cluster NGC 5824
• A New Cold Stream near the Southern Galactic Pole
• A Dwarf Galaxy Debris Stream Associated with Palomar 1 and the Anticenter Stream
• The mass and redshift dependence of halo star clustering