A Blueprint for the Milky Way's Stellar Populations: The Power of Large Photometric and Astrometric Surveys

Abstract

Recent advances from astronomical surveys have revealed spatial, chemical, and kinematical inhomogeneities in the inner region of the stellar halo of the Milky Way Galaxy. In particular, large spectroscopic surveys, combined with Gaia astrometric data, have provided powerful tools for analyzing the detailed abundances and accurate kinematics for individual stars. Despite these noteworthy efforts, however, spectroscopic samples are typically limited by the numbers of stars considered; their analysis and interpretation are also hampered by the complex selection functions that are often employed. Here we present a powerful alternative approach $-$ a synoptic view of the spatial, chemical, and kinematical distributions of stars in the Milky Way based on large photometric survey databases, enabled by a well-calibrated technique for obtaining individual stellar metal abundances from broad-band photometry. We combine metallicities with accurate proper motions from the Gaia mission along the Prime Meridian of the Galaxy, and find that various stellar components are clearly separated from each other in the metallicity versus rotation-velocity space. The observed metallicity distribution of the inner-halo stars deviates from the traditional single-peaked distribution, and exhibits complex substructures comprising varying contributions from individual stellar populations, sometimes with striking double peaks at low metallicities. The substructures revealed from our less-biased, comprehensive maps demonstrate the clear advantages of this approach, which can be built upon by future mixed-band and broad-band photometric surveys, and used as a blueprint for identifying the stars of greatest interest for upcoming spectroscopic studies.

arXiv comment15 pages, 11 figures. Accepted for publication in the Astrophysical Journal after minor revision

References in corpus (59)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Gaia Data Release 2. Summary of the contents and survey properties
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• LSST: from Science Drivers to Reference Design and Anticipated Data Products
• Gaia Data Release 2: The astrometric solution
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• Tracing Galaxy Formation with Stellar Halos I: Methods
• Co-formation of the Galactic disc and the stellar halo
• The GALAH Survey: Scientific Motivation
• A standard stellar library for evolutionary synthesis: I. Calibration of theoretical spectra
• Kinematics of Metal-Poor Stars in the Galaxy. III. Formation of the Stellar Halo and Thick Disk as Revealed from a Large Sample of Non-Kinematically Selected Stars
• The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
• Two Stellar Components in the Halo of the Milky Way
• The Milky Way Tomography with SDSS: II. Stellar Metallicity
• Two distinct halo populations in the solar neighborhood. Evidence from stellar abundance ratios and kinematics
• The SEGUE Stellar Parameter Pipeline. I. Description and Initial Validation Tests
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
• The ACS Survey of Galactic Globular Clusters. XII. Photometric Binaries along the Main-Sequence
• SkyMapper Southern Survey: First Data Release (DR1)
• The GALAH Survey: Second Data Release
• Photometric Calibration of the First 1.5 Years of the Pan-STARRS1 Survey
• The Dual Origin of Stellar Halos
• Galactic Rotation and Solar Motion from Stellar Kinematics
• The Biggest Splash
• The origin of accreted stellar halo populations in the Milky Way using APOGEE, $\text{Gaia}$, and the EAGLE simulations
• J-PLUS: The Javalambre Photometric Local Universe Survey
• Mapping the stellar structure of the Milky Way thick disk and halo using SEGUE photometry
• Light Curve Templates and Galactic Distribution of RR Lyrae Stars from Sloan Digital Sky Survey Stripe 82
• The Milky Way has no in-situ halo other than the heated thick disc. Composition of the stellar halo and age-dating the last significant merger with Gaia DR2 and APOGEE
• The Angular Momentum Evolution of Very Low Mass Stars
• Formation and Evolution of the Disk System of the Milky Way: [alpha/Fe] Ratios and Kinematics of the SEGUE G-Dwarf Sample
• The Milky Way Tomography with SDSS: III. Stellar Kinematics
• The Southern Photometric Local Universe Survey (S-PLUS): improved SEDs, morphologies and redshifts with 12 optical filters
• Gaia reveals a metal-rich in-situ component of the local stellar halo
• One large blob and many streams frosting the nearby stellar halo in Gaia DR2
• The Case for the Dual Halo of the Milky Way
• The Distances to Open Clusters from Main-Sequence Fitting. III. Improved Accuracy with Empirically Calibrated Isochrones
• Galactic Globular and Open Clusters in the Sloan Digital Sky Survey. I. Crowded Field Photometry and Cluster Fiducial Sequences in ugriz
• Disentangling the Galactic Halo with APOGEE: I. Chemical and Kinematical Investigation of Distinct Metal-Poor Populations
• Stellar haloes of simulated Milky Way-like galaxies: Chemical and kinematic properties
• The origin of the diverse morphologies and kinematics of Milky Way-mass galaxies in the FIRE-2 simulations
• The Stellar Metallicity Distribution Function of the Galactic Halo from SDSS Photometry
• Resolving the Metallicity Distribution of the Stellar Halo with the H3 Survey
• Hypercalibration: A Pan-STARRS1-based recalibration of the Sloan Digital Sky Survey
• Origin of the excess of high-energy retrograde stars in the Galactic halo
• Galactic Globular and Open Clusters in the Sloan Digital Sky Survey. II. Test of Theoretical Stellar Isochrones
• Population Studies. XIII. A New Analysis of the Bidelman-MacConnell "Weak-Metal" Stars - Confirmation of Metal-Poor Stars in the Thick Disk of the Galaxy
• A dynamical and kinematical model of the Galactic stellar halo and possible implications for galaxy formation scenarios
• The Fractions of Inner- and Outer-Halo Stars in the Local Volume
• Evidence for the Third Stellar Population in the Milky Way's Disk
• The tale of the tail -- disentangling the high transverse velocity stars in Gaia DR2
• Chemical trends in the Galactic Halo with APOGEE data
• A new sample of southern radio galaxies: Host galaxy masses and star-formation rates
• The Distances to Open Clusters from Main-Sequence Fitting. V. Extension of Color Calibration and Test using Cool and Metal-Rich Stars in NGC 6791
• Photometric Metallicity Calibration with SDSS and SCUSS and its Application to distant stars in the South Galactic Cap
• Asymmetric Mean Metallicity Distribution of the Milky Way's Disk

Cited by in corpus (30)

• Dynamically Tagged Groups of Very Metal-poor Halo Stars from the HK and Hamburg/ESO Surveys
• Beyond spectroscopy. I. Metallicities, distances, and age estimates for over twenty million stars from SMSS DR2 and Gaia EDR3
• The R-Process Alliance: Chemo-Dynamically Tagged Groups of Halo $r$-Process-Enhanced Stars Reveal a Shared Chemical-Evolution History
• The Atari Disk, a Metal-Poor Stellar Population in the Disk System of the Milky Way
• The Photometric Metallicity and Carbon Distributions of the Milky Way's Halo and Solar Neighborhood from S-PLUS Observations of SDSS Stripe 82
• Stellar Metallicities from SkyMapper Photometry II: Precise photometric metallicities of $\sim$280,000 giant stars with [Fe/H] $<-0.75$ in the Milky Way
• Chasing Accreted Structures within Gaia DR2 using Deep Learning
• Dynamically Tagged Groups of Metal-Poor Stars from the Best \& Brightest Survey
• Cosmological Insights into the Early Accretion of \textit{r}-Process-Enhanced stars. I. A Comprehensive Chemo-dynamical Analysis of LAMOST J1109+0754
• The Pristine survey XIII: Uncovering the very metal-poor tail of the thin disc
• Stellar Loci V: Photometric Metallicities of 27 Million FGK Stars based on Gaia Early Data Release 3
• Chemo-Dynamically Tagged Groups of CEMP Stars in the Halo of the Milky Way. I. Untangling the Origins of CEMP-$s$ and CEMP-no Stars
• The R-Process Alliance: Chemo-Dynamically Tagged Groups II. An Extended Sample of Halo $r$-Process-Enhanced Stars
• The Metal-Poor Metallicity Distribution of the Ancient Milky Way
• Dynamically Tagged Groups of Metal-Poor Stars II. The Radial Velocity Experiment Data Release 6
• Jurassic: A Chemically Anomalous Structure in the Galactic Halo
• Targeting Bright Metal-poor Stars in the Disk and Halo Systems of the Galaxy
• A Blueprint for the Milky Way's Stellar Populations. III. Spatial Distributions and Population Fractions of Local Halo Stars
• Candidate Members of the VMP/EMP Disk System of the Galaxy from the SkyMapper and SAGES Surveys
• A Blueprint for the Milky Way's Stellar Populations. II. Improved Isochrone Calibration in the SDSS and Pan-STARRS Photometric Systems
• Chemodynamical Analysis of Metal-rich High-eccentricity Stars in the Milky Way's Disk
• Proper motion measurements for stars up to $100$ kpc with Subaru HSC and SDSS Stripe 82
• A Blueprint for the Milky Way's Stellar Populations. IV. A String of Pearls $-$ the Galactic Starburst Sequence
• Stellar Loci VI: An Updated Catalog of the Best and Brightest Metal-poor Stars
• A Blueprint for the Milky Way's Stellar Populations. V. 3D Local Dust Extinction
• High-Resolution Chemical Abundances of the Nyx Stream
• Deciphering the Milky Way disc formation time encrypted in the bar chrono-kinematics
• Search for the metal-weak thick disk from the LAMOST DR5
• Deciphering the Milky Way's star formation at cosmic noon with high proper-motion stars: A precursor to the merger-driven starburst
• New families in our Solar neighborhood: applying Gaussian Mixture models for objective classification of structures in the Milky Way and in simulations