Stellar Abundance Maps of the Milky Way Disk

Abstract

To understand the formation of the Milky Way's prominent bar it is important to know whether stars in the bar differ in the chemical element composition of their birth material as compared to disk stars. This requires stellar abundance measurements for large samples across the Milky Way's body. Such samples, e.g. luminous red giant stars observed by SDSS's Apogee survey, will inevitably span a range of stellar parameters; as a consequence, both modelling imperfections and stellar evolution may preclude consistent and precise estimates of their chemical composition at a level of purported bar signatures, which has left current analyses of a chemically distinct bar inconclusive. Here, we develop a new self-calibration approach to eliminate both modelling and astrophysical abundance systematics among red giant branch (RGB) stars of different luminosities (and hence surface gravity $\log g$). We apply our method to $48,853$ luminous Apogee DR16 RGB stars to construct spatial abundance maps of $20$ chemical elements near the Milky Way's mid-plane, covering Galactocentric radii of $0\mathrm{kpc}<R_{\mathrm{GC}}<20\mathrm{kpc}$. Our results indicate that there are no abundance variations whose geometry matches that of the bar, and that the mean abundance gradients vary smoothly and monotonically with Galactocentric radius. We confirm that the high-$\alpha$ disk is chemically homogeneous, without spatial gradients. Furthermore, we present the most precise [Fe/H] vs. $R_{\mathrm{GC}}$ gradient to date with a slope of $-0.057\pm 0.001\mathrm{dex}\mathrm{kp}{\mathrm{c}}^{-1}$ out to approximately $15$ kpc.

arXiv commentApJ accepted

References in corpus (59)

• Array Programming with NumPy
• emcee: The MCMC Hammer
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• 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
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• The New Galaxy: Signatures of its Formation
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
• APOGEE Data and Spectral Analysis from SDSS Data Release 16: Seven Years of Observations Including First Results from APOGEE-South
• The Data Reduction Pipeline for the Apache Point Observatory Galactic Evolution Experiment
• Abundances, Stellar Parameters, and Spectra From the SDSS-III/APOGEE Survey
• The Circular Velocity Curve of the Milky Way from $5$ to $25$ kpc
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
• Target Selection for the SDSS-IV APOGEE-2 Survey
• APOGEE Data Releases 13 and 14: Data and Analysis
• Red giant masses and ages derived from carbon and nitrogen abundances
• The Milky Way's Stellar Disk
• The stellar population structure of the Galactic disk
• Dynamical heating across the Milky Way disc using APOGEE and $Gaia$
• Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar
• Spectroscopic determination of masses (and implied ages) for red giants
• Tracing chemical evolution over the extent of the Milky Way's Disk with APOGEE Red Clump Stars
• Deep learning of multi-element abundances from high-resolution spectroscopic data
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. IV. Two bulge populations
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. VI. Age and abundance structure of the stellar populations in the central sub-kpc of the Milky Way
• Accuracy and precision of industrial stellar abundances
• On the origin of the chemical bimodality of disk stars: A tale of merger and migration
• From the bulge to the outer disc: StarHorse stellar parameters, distances, and extinctions for stars in APOGEE DR16 and other spectroscopic surveys
• Simultaneous calibration of spectro-photometric distances and the Gaia DR2 parallax zero-point offset with deep learning
• The influence of atomic diffusion on stellar ages and chemical tagging
• The Open Cluster Chemical Abundances and Mapping Survey: IV. Abundances for 128 Open Clusters using SDSS/APOGEE DR16
• Measuring Radial Orbit Migration in the Milky Way Disk
• APOGEE Data Releases 13 and 14: Stellar Parameter and Abundance Comparisons With Independent Analyses
• The chemical homogeneity of open clusters
• Chemical Cartography with APOGEE: Multi-element abundance ratios
• The Galactic Disc in Action Space as seen by Gaia DR2
• An accurate and self-consistent chemical abundance catalogue for the APOGEE/Kepler sample
• The Inside-out Growth of the Galactic Disk
• Keeping it Cool: Much Orbit Migration, yet Little Heating, in the Galactic Disk
• Extended distribution functions for our Galaxy
• The disc origin of the Milky Way bulge: Dissecting the chemo-morphological relations using N-body simulations and APOGEE
• In the Galactic disk, stellar [Fe/H] and age predict orbits and precise [X/Fe]
• Mapping the Galactic Metallicity Gradient with Open Clusters: The State-of-the-Art and Future Challenges
• The Similarity of Abundance Ratio Trends and Nucleosynthetic Patterns in the Milky Way Disk and Bulge
• Spectrophotometric parallaxes with linear models: Accurate distances for luminous red-giant stars
• Orbital Torus Imaging: Using Element Abundances to Map Orbits and Mass in the Milky Way
• The AMBRE Project: Spectrum normalisation influence on Mg abundances in the metal-rich Galactic disc
• High- and Low-$\alpha$ Disk Stars Separate Dynamically at all Ages
• The chemical properties of the Milky Way's on-bar and off-bar regions: evidence for inhomogeneous star formation history in the bulge
• Actions are weak stellar age indicators in the Milky Way disk
• Tracing birth properties of stars with abundance clustering

Cited by in corpus (26)

• The Poor Old Heart of the Milky Way
• A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
• A direct measurement of the distance to the Galactic center using the kinematics of bar stars
• Unveiling the time evolution of chemical abundances across the Milky Way disk with APOGEE
• Chemical Cartography with APOGEE: Mapping Disk Populations with a Two-Process Model and Residual Abundances
• Migration and Mixing in the Galactic Disc from Encounters between Sagittarius and the Milky Way
• Reliability and limitations of inferring birth radii in the Milky Way disk
• The imprint of clump formation at high redshift. II. The chemistry of the bulge
• The Gaia-ESO Survey: Old super-metal-rich visitors from the inner Galaxy
• Chemical Cartography with APOGEE: Two-process Parameters and Residual Abundances for 288,789 Stars from Data Release 17
• The Non-Axisymmetric Influence: Radius and Angle-Dependent Trends in a Barred Galaxy
• The chemical enrichment of the Milky Way disk evaluated using conditional abundances
• Is Terzan 5 the remnant of a building block of the Galactic bulge? Evidence from APOGEE
• SpectroTranslator: a deep-neural network algorithm to homogenize spectroscopic parameters
• Rediscovering the Milky Way with orbit superposition approach and APOGEE data II. Chrono-chemo-kinematics of the disc
• Rediscovering the Milky Way with orbit superposition approach and APOGEE data I. Method validation
• Are Milky-Way-like galaxies like the Milky Way? A view from SDSS-IV/MaNGA
• A Galactic Self-Portrait: Density Structure and Integrated Properties of the Milky Way Disk
• Effects of physical conditions on the stellar initial mass function: The low-metallicity star-forming region Sh 2-209
• Metallicities of old open clusters: A new Galactic map
• Milky Way's Metal-Poor Stars display Chemical Transition near the Solar Radius
• Nuclear astrophysics
• The impact of relativistic corrections on the detectability of dark-matter spikes with gravitational waves
• 3D elemental abundances of stars at formation across the histories of Milky Way-mass galaxies in the FIRE simulations
• Neutron-capture elements record the ordered chemical evolution of the disc over time
• Recovering Signals in CoRoT Mission (RSCoRoT): I. Short Period Variable Stars