Unveiling Galactic substructures with M Giant stars: A kinematic and chemical study based on LAMOST DR9, Gaia DR3 and APOGEE DR17

Abstract

Based on the updated M giant star catalog selected from LAMOST DR9, we iden-tify substructures within the integrals-of-motion space through Friends-of-Friends cluster-ing algorithm. We obtain members belonging to several known substructures: the Sagittarius stream, Galactic Anticenter Substructure (GASS), Gaia-Enceladus-Sausage (GES), Splash, and the high-α disk. Furthermore, we also identify two groups which cannot be clearly asso-ciated with previously known substructures. Our findings confirm the existence of metal-rich constituents within the GES, representing newly formed stars that originated from the metal-enriched gas delivered during the GES merger event and subsequently evolved. Additionally, this study further expands the sample of GASS, high-α disk, and Splash stars. Analysis of these metal-rich M giant stars as members of the GES, Splash, and high-α disk compo-nents supports an evolution scenario for the early Milky Way, as proposed by previous stud-ies. In this scenario, stars initially formed in a high-α primordial disk were dynamically heated by the massive accretion event (GES). This process redistributed stellar orbits, creat-ing the Splash population, while the undisturbed portion of the primordial disk persisted as the present-day high-α disk component.

References in corpus (22)

• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• The Gaia-ESO Survey: the Galactic Thick to Thin Disc transition
• Rings and Radial Waves in the Disk of the Milky Way
• A time-resolved picture of our Milky Way's early formation history
• The Hercules-Aquila Cloud
• High-precision abundances of elements in solar-type stars. Evidence of two distinct sequences in abundance-age relations
• Timing the Early Assembly of the Milky Way with the H3 Survey
• Self-consistent Stellar Radial Velocities from LAMOST Medium-Resolution Survey (MRS) DR7
• VLT/FLAMES spectroscopy of red giant branch stars in the Fornax dwarf spheroidal galaxy
• Overview of the LAMOST survey in the first decade
• A Low-Mass Stellar-Debris Stream Associated with a Globular Cluster Pair in the Halo
• The Geometry of Sagittarius Stream from Pan-STARRS1 3$\pi$ RR Lyrae
• TriAnd and its Siblings: Satellites of Satellites in the Milky Way Halo
• The tale of the tail -- disentangling the high transverse velocity stars in Gaia DR2
• Tracing Kinematic and Chemical Properties of Sagittarius Stream by K-Giants, M-Giants, and BHB stars
• Detecting the Sagittarius stream with LAMOST DR4 M giants \& Gaia DR2
• Probing the Galactic Halo with RR Lyrae Stars. II. The Substructures of the Milky Way
• Exploring the Galactic Anticenter substructure with LAMOST & Gaia DR2
• Value-added catalog of M-giant stars in LAMOST DR9
• Atmospheric parameters and kinematic information for the M giants stars from LAMOST DR9
• A New Tidal Stream Discovered in Gaia DR3