Aluminum Enhanced Metal-Poor Stars buried in the Inner Galaxy

Abstract

Stars with higher aluminum and nitrogen enrichment are often the key pieces for the chemical makeup of multiple populations in almost all globular clusters (GCs). There is also compelling observational evidence that some Galactic components could be partially built from dissipated GCs. Thus, the identification of such kinds of stars among metal-poor field stars may provide insights on the composite nature of the Milky Way (MW) bulge and inner stellar halo, as well as reveal other chemical peculiarities. Here, based on APOGEE spectra, we report the discovery of 29 mildly metal-poor ([Fe/H]$\lesssim -0.7$) stars with stellar atmospheres strongly enriched in aluminum (Al-rich stars: [Al/Fe]$\gtrsim +0.5$), well above the typical Galactic levels, located within the Solar radius toward the bulge region, which lies in highly eccentric orbits ($e\gtrsim 0.6$). We find many similarities for almost all of the chemical species measured in this work with the chemical patterns of GCs, so we conjecture that they have likely been dynamically ejected into the bulge and inner halo from GCs formed in situ and/or GC formed in different progenitors of known merger events experienced by the MW, such as the \textit{Gaia}-Sausage-Enceladus and/or Sequoia.

arXiv commentAccepted for publication on Astronomy & Astrophysics Letters. 11 pages, 6 figures, 2 tables

References in corpus (48)

• Gaia Data Release 2. Summary of the contents and survey properties
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• Gaia Data Release 2: The astrometric solution
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
• Astrophysics Source Code Library
• Co-formation of the Galactic disc and the stellar halo
• ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline
• Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
• Mean proper motions, space orbits and velocity dispersion profiles of Galactic globular clusters derived from Gaia DR2 data
• Origin of the system of globular clusters in the Milky Way
• The Data Reduction Pipeline for the Apache Point Observatory Galactic Evolution Experiment
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• The Metal Content of Bulge Field Stars from FLAMES-GIRAFFE Spectra. I. Stellar parameters and Iron Abundances
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
• APOGEE Data Releases 13 and 14: Data and Analysis
• Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar
• The Sausage Globular Clusters
• Chemodynamical history of the Galactic Bulge
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy
• From the bulge to the outer disc: StarHorse stellar parameters, distances, and extinctions for stars in APOGEE DR16 and other spectroscopic surveys
• Homogeneous Analysis of Globular Clusters from the APOGEE Survey with the BACCHUS Code. II. The Southern Clusters and Overview
• APOGEE Data Releases 13 and 14: Stellar Parameter and Abundance Comparisons With Independent Analyses
• Ages and kinematics of chemically selected, accreted Milky Way halo stars
• Accretion relicts in the solar neighbourhood: debris from omegaCen's parent galaxy
• Characterization and history of the Helmi streams with Gaia DR2
• A homogeneous analysis of globular clusters from the APOGEE survey with the BACCHUS code. I. The Northern clusters
• Chemical tagging in the SDSS-III/APOGEE survey: new identifications of halo stars with globular cluster origins
• Atypical Mg-poor Milky Way field stars with globular cluster second-generation like chemical patterns
• Exploring Halo Substructure with Giant Stars: Substructure in the Local Halo as Seen in the Grid Giant Star Survey Including Extended Tidal Debris from Omega Centauri
• How Many Components? Quantifying the Complexity of the Metallicity Distribution in the Milky Way Bulge with APOGEE
• Field Stars and Clusters of the Galactic Bulge: Implications for Galaxy Formation
• Discovery of a Metal-Poor Field Giant with a Globular Cluster Second-Generation Abundance Pattern
• The Relationship Between Globular Cluster Mass, Metallicity, and Light Element Abundance Variations
• Chemodynamics of newly identified giants with globular cluster like abundance patterns in the bulge, disk, and halo of the Milky Way
• Identifying Sagittarius Stream Stars By Their APOGEE Chemical Abundance Signatures
• The Gaia-ESO Survey: low-alpha element stars in the Galactic Bulge
• Discovery of a new stellar sub-population residing in the (inner) stellar halo of the Milky Way
• The COMBS survey I: Chemical Origins of Metal-Poor Stars in the Galactic Bulge
• H-band discovery of additional Second-Generation stars in the Galactic Bulge Globular Cluster NGC 6522 as observed by APOGEE and Gaia
• Dynamical Orbital classification of selected N-rich stars with \textit{Gaia} DR2 astrometry
• Self-consistent analysis of stellar clusters: An application to HST data of the halo globular cluster NGC 6752
• The enigmatic globular cluster UKS~1 obscured by the bulge: \textit{H}-band discovery of nitrogen-enhanced stars
• Discovery of a nitrogen-enhanced mildly metal-poor binary system: Possible evidence for pollution from an extinct AGB Star
• Formation of N-rich field stars in the high-density building blocks of the Galactic bulge

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• Spectroscopic Observations of Obscured Populations in the Inner Galaxy: 2MASS-GC02, Terzan 4, and the 200 km/s stellar peak
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• CAPOS: The bulge Cluster APOGEE Survey VI. Characterizing multiple stellar populations and chemical abundances in the bulge globular cluster NGC 6569
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