A Blueprint for the Milky Way's Stellar Populations. II. Improved Isochrone Calibration in the SDSS and Pan-STARRS Photometric Systems

Abstract

We improve the identification and isolation of individual stellar populations in the Galactic halo based on an updated set of empirically calibrated stellar isochrones in the Sloan Digital Sky Survey (SDSS) and Pan-STARRS 1 (PS1) photometric systems. Along the Galactic prime meridian ($l=0^{\circ }$ and $180^{\circ }$), where proper motions and parallaxes from Gaia DR2 can be used to compute rotational velocities of stars in the rest frame of the Milky Way, we use the observed double color-magnitude sequences of stars having large transverse motions, which are attributed to groups of stars in the metal-poor halo and the thick disk with halo-like kinematics, respectively. The Gaia sequences directly constrain color-magnitude relations of model colors, and help to improve our previous calibration using Galactic star clusters. Based on these updated sets of stellar isochrones, we confirm earlier results on the presence of distinct groups of stars in the metallicity versus rotational-velocity plane, and find that the distribution of the most metal-poor ([Fe/H] $<-2$) stars in our sample can be modeled using two separate groups on prograde and retrograde orbits, respectively. At $4$-$6$ kpc from the Galactic plane, we find approximately equal proportions of the Splashed Disk, and the metal-rich ($⟨[Fe/H]⟩\sim -1.6$) and metal-poor ($⟨[Fe/H]⟩\sim -2.5$) halos on prograde orbits. The Gaia-Sausage-Enceladus, the metal-weak thick disk, and the retrograde halo structure(s) ($⟨[Fe/H]⟩\sim -2.2$) constitute approximately $10\%$ of the rest of the stellar populations at these distances.

arXiv comment19 pages, 11 figures, 3 tables, accepted for publication in the Astrophysical Journal

References in corpus (55)

• 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
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20
• Co-formation of the Galactic disc and the stellar halo
• The Pan-STARRS1 Photometric System
• A standard stellar library for evolutionary synthesis: I. Calibration of theoretical spectra
• Stellar Chemical Signatures And Hierarchical Galaxy Formation
• Gaia Data Release 2: Kinematics of globular clusters and dwarf galaxies around the Milky Way
• Two Stellar Components in the Halo of the Milky Way
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• Debris streams in the solar neighbourhood as relicts from the formation of the Milky Way
• A standard stellar library for evolutionary synthesis: II. The M dwarf extension
• Two distinct halo populations in the solar neighborhood. Evidence from stellar abundance ratios and kinematics
• 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
• Three Dimensional Structure of the Milky Way Disk
• Streams, substructures and the early history of the Milky Way
• SkyMapper Southern Survey: First Data Release (DR1)
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• The YY Isochrones for alpha-element Enhanced Mixtures
• The GALAH Survey: Second Data Release
• Distances, ages, and epoch of formation of globular clusters
• A Globular Cluster Metallicity Scale Based on the Abundance of Fe II
• The Biggest Splash
• A standard stellar library for evolutionary synthesis. III. Metallicity calibration
• Multiple retrograde substructures in the Galactic halo: A shattered view of Galactic history
• The Angular Momentum Evolution of Very Low Mass Stars
• Gaia reveals a metal-rich in-situ component of the local stellar halo
• Younger and brighter - New distances to globular clusters based on Hipparcos parallax measurements of local subdwarfs
• 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
• Supercal: Cross-Calibration of Multiple Photometric Systems to Improve Cosmological Measurements with Type Ia Supernovae
• The Stellar Metallicity Distribution Function of the Galactic Halo from SDSS Photometry
• 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
• The Distances to Open Clusters from Main-Sequence Fitting. I. New Models and a Comparison to the Properties of the Hyades Eclipsing Binary vB 22
• The Fractions of Inner- and Outer-Halo Stars in the Local Volume
• Evidence for the Third Stellar Population in the Milky Way's Disk
• A Blueprint for the Milky Way's Stellar Populations: The Power of Large Photometric and Astrometric Surveys
• A Photometric Metallicity Estimate of the Virgo Stellar Overdensity
• The Distances to Open Clusters as Derived from Main-sequence Fitting. II. Construction of Empirically Calibrated Isochrones
• Three-dimensional structure of the milky way dust: modeling of LAMOST data
• Characteristics of the two sequences seen in the high-velocity Hertzsprung-Russell diagram in Gaia DR2
• Galactic Globular and Open Cluster Fiducial Sequences in the Pan-STARRS1 Photometric System
• Comparison of the Asteroseismic Mass Scale of Red Clump Giants with Photometric Mass Estimates
• 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
• Asymmetric Mean Metallicity Distribution of the Milky Way's Disk

Cited by in corpus (11)

• Reconstructing the Last Major Merger of the Milky Way with the H3 Survey
• Reconstructing the Disrupted Dwarf Galaxy $Gaia$-Sausage/Enceladus Using its Stars and Globular Clusters
• Beyond spectroscopy. I. Metallicities, distances, and age estimates for over twenty million stars from SMSS DR2 and Gaia EDR3
• The Pristine survey -- XVI. The metallicity of 26 stellar streams around the Milky Way detected with the STREAMFINDER in Gaia EDR3
• Stellar Loci V: Photometric Metallicities of 27 Million FGK Stars based on Gaia Early Data Release 3
• 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
• Chemodynamical Analysis of Metal-rich High-eccentricity Stars in the Milky Way's Disk
• A Blueprint for the Milky Way's Stellar Populations. IV. A String of Pearls $-$ the Galactic Starburst Sequence
• A Blueprint for the Milky Way's Stellar Populations. V. 3D Local Dust Extinction
• Deciphering the Milky Way's star formation at cosmic noon with high proper-motion stars: A precursor to the merger-driven starburst