Detailed Abundances for the Old Population near the Galactic Center: I. Metallicity distribution of the Nuclear Star Cluster

Abstract

We report the first high spectral resolution study of 17 M giants kinematically confirmed to lie within a few parsecs of the Galactic Center, using R=24,000 spectroscopy from Keck/NIRSPEC and a new linelist for the infrared K band. We consider their luminosities and kinematics, which classify these stars as members of the older stellar population and the central cluster. We find a median metallicity of <[Fe/H]>=-0.16 and a large spread from approximately -0.3 to +0.3 (quartiles). We find that the highest metallicities are [Fe/H]<+0.6, with most of the stars being at or below the Solar iron abundance. The abundances and the abundance distribution strongly resembles that of the Galactic bulge rather than disk or halo; in our small sample we find no statistical evidence for a dependence of velocity dispersion on metallicity.

18 pages, 14 figures, accepted for publication in AJ

References in corpus (15)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• The old nuclear star cluster in the Milky Way: dynamics, mass, statistical parallax, and black hole mass
• Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra
• Stellar Proper Motions in the Galactic Bulge from deep HST ACS/WFC Photometry
• Chemical Abundances of Luminous Cool Stars in the Galactic Center from High-Resolution Infrared Spectroscopy
• Kinematics of the old stellar population at the Galactic Center
• Mapping the Milky Way bulge at high resolution: the 3D dust extinction, CO, and X factor maps
• KMOS view of the Galactic Centre - II. Metallicity distribution of late-type stars
• Experimental and theoretical oscillator strengths of Mg I for accurate abundance analysis
• Discovery of RR Lyrae Stars in the Nuclear Bulge of the Milky Way
• Chemical Abundances of M giants in the Galactic Center: a Single Metal-Rich Population with Low [alpha/Fe]
• Near-Infrared Variability Study of the Central 2.3 arcmin x 2.3 arcmin of the Galactic Centre II. Identification of RR Lyrae Stars in the Milky Way Nuclear Star Cluster
• Chemical evolution of the Galactic Center
• Effects of the selection function on metallicity trends in spectroscopic surveys of the Milky Way

Cited by in corpus (35)

• Nuclear Star Clusters
• The Milky Way's nuclear star cluster: Old, metal-rich, and cuspy
• High Eccentricities and High Masses Characterize Gravitational-wave Captures in Galactic Nuclei as Seen by Earth-based Detectors
• Diversity of nuclear star cluster formation mechanisms revealed by their star formation histories
• The Milky Way's nuclear stellar disc: A dynamically cool and metal-rich component formed from the Central Molecular Zone?
• The inner two degrees of the Milky Way. Evidence of a chemical difference between the Galactic Center and the surrounding inner bulge stellar populations
• Detailed abundances in the Galactic center: Evidence of a metal-rich alpha-enhanced stellar population
• Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky Way
• The Star Formation History of the Milky Way's Nuclear Star Cluster
• Asymmetric spatial distribution of sub-solar metallicity stars in the Milky Way nuclear star cluster
• Abundances of disk and Bulge giants from high-resolution optical spectra III. Sc, V, Cr, Mn, Co, Ni
• Magnesium and silicon in interstellar dust: an X-ray overview
• Disentangling the formation mechanisms of nuclear star clusters
• Revealing the Formation of the Milky Way Nuclear Star Cluster via Chemo-Dynamical Modeling
• 2D kinematics of massive stars near the Galactic Center
• Constraints on the Galactic Centre environment from Gaia hypervelocity stars
• Stellar Populations in the Transition Region of Nuclear Star Cluster and Nuclear Stellar Disc
• Comparing hypervelocity star populations from the Large Magellanic Cloud and the Milky Way
• M giants with IGRINS I. Stellar parameters and $\alpha$-abundance trends of the solar neighborhood population
• Kinematic data rebuild the Nuclear star cluster as the most metal rich region of the Galaxy
• Fluorine Abundances in the Galactic Nuclear Star Cluster
• Constraints on the Galactic Centre environment from Gaia hypervelocity stars II: The evolved population
• Detailed $\alpha$ abundance trends in the inner Galactic bulge
• Evidence of Deep Mixing in IRS 7, a Cool Massive Supergiant Member of the Galactic Nuclear Star Cluster
• Photometric Classification of Stars Around the Milky Way's Central Black Hole: I. Central Parsec
• A spectroscopic map of the Galactic centre -- Observations and resolved stars
• Measuring the alpha-abundance of subsolar-metallicity stars in the Milky Way's central half-parsec: testing globular cluster and dwarf galaxy infall scenarios
• On the manifest link between Terzan 5 and the Galactic bulge
• The S stars' zone of avoidance in the Galactic center
• A Wide Metallicity Range for Gyr-old Stars in the Nuclear Star Cluster
• The multi-zone chemical evolution of the Galactic bulge: predicting abundances for different radial zones
• Chandra X-ray Measurement of Heavy Element Abundances of Wolf-Rayet Stars in the Galactic Center
• New Temperature and Metallicity Scale of Cool Giants from K-band Spectra
• The Near-Infrared Spectrum of the Nuclear Star Cluster: Looking Below the Tip of the Iceberg and Comparisons with Extragalactic Nuclei
• Supergiant GCIRS 22 in the Milky Way Nuclear Star Cluster: Revised alpha abundances