The Pristine survey XIII: Uncovering the very metal-poor tail of the thin disc

Abstract

We evaluate the rotational velocity of stars observed by the Pristine survey towards the Galactic anticentre, spanning a wide range of metallicities from the extremely metal-poor regime ($[Fe/H]<-3$) to nearly solar metallicity. In the Galactic anticentre direction, the rotational velocity ($V_{\varphi }$) is similar to the tangential velocity in the galactic longitude direction ($V_{\ell }$). This allows us to estimate $V_{\varphi }$ from Gaia early data-release 3 (Gaia EDR3) proper motions for stars without radial velocity measurements. This substantially increases the sample of stars in the outer disc with estimated rotational velocities. Our stellar sample towards the anticentre is dominated by a kinematical thin disc with a mean rotation of $\sim -220$ km ${\mathrm{s}}^{-1}$. However, our analysis reveals the presence of more stellar substructures. The most intriguing is a well populated extension of the kinematical thin disc down to $[Fe/H]\sim -2$. A scarser fast rotating population reaching the extremely metal-poor regime, down to $[Fe/H]\sim -3.5$ is also detected, but without statistical significance to unambiguously state whether this is the extremely metal-poor extension of the thin disc or the high rotating tail of hotter structures (like the thick disc or the halo). In addition, a more slowly rotating kinematical thick disc component is also required to explain the observed $V_{\ell }$ distribution at $[Fe/H]>-1.5$. Furthermore, we detect signatures of a "heated disc", the so-called Splash, at metallicities higher than $\sim -1.5$. Finally, at $[Fe/H]<-1.5$ our anticentre sample is dominated by a kinematical halo with a net prograde motion.

arXiv comment18 pages, 14 figures. Accepted for publication in MNRAS

References in corpus (90)

• Scikit-learn: Machine Learning in Python
• 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
• The Gaia mission
• The Seventh Data Release of the Sloan Digital Sky Survey
• Hierarchical Galaxy Formation
• Local Kinematics and the Local Standard of Rest
• The Sloan Digital Sky Survey Photometric Camera
• 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
• The New Galaxy: Signatures of its Formation
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• Co-formation of the Galactic disc and the stellar halo
• The Chemical Evolution of the Galaxy: the two-infall model
• 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
• Abundance Gradients and the Formation of the Milky Way
• Near-Field Cosmology with Metal-Poor Stars
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• Estimating distances from parallaxes
• Chemodynamical evolution of the Milky Way disk I: The solar vicinity
• Gaia Data Release 2: Mapping the Milky Way disc kinematics
• In disguise or out of reach: first clues about in-situ and accreted stars in the stellar halo of the Milky Way from Gaia DR2
• Photometric Response Functions of the SDSS Imager
• Outer structure of the Galactic warp and flare: explaining the Canis Major over-density
• 4MOST: Project overview and information for the First Call for Proposals
• Galactic Rotation and Solar Motion from Stellar Kinematics
• The Biggest Splash
• Footprints of the Sagittarius dwarf galaxy in the $Gaia$ data set
• Old stellar Galactic disc in near-plane regions according to 2MASS: scales, cut-off, flare and warp
• The birth of the Milky Way as uncovered by accurate stellar ages with Gaia
• The Pristine survey I: Mining the Galaxy for the most metal-poor stars
• The Gaia-ESO Survey: the Galactic Thick to Thin Disc transition
• 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
• Formation and Evolution of the Disk System of the Milky Way: [alpha/Fe] Ratios and Kinematics of the SEGUE G-Dwarf Sample
• Using chemical tagging to redefine the interface of the Galactic disk and halo
• The Sausage Globular Clusters
• Galactic Archaeology with asteroseismic ages: evidence for delayed gas infall in the formation of the Milky Way disc
• A three-dimensional map of the Milky Way using classical Cepheid variable stars
• Chemical Cartography with APOGEE: Large-scale Mean Metallicity Maps of the Milky Way
• Kinematics and chemical properties of the Galactic stellar populations. The HARPS FGK dwarfs sample
• Where are the most ancient stars in the Milky Way?
• Disentangling the Galactic Halo with APOGEE: I. Chemical and Kinematical Investigation of Distinct Metal-Poor Populations
• The Milky Way's external disc constrained by 2MASS star counts
• An intuitive 3D map of the Galactic warp's precession traced by classical Cepheids
• Sausage & Mash: The dual origin of the Galactic thick disc and halo from the gas-rich Gaia-Enceladus-Sausage merger
• A spectroscopic survey of thick disc stars outside the solar neighbourhood
• Tracing the formation of the Milky Way through ultra metal-poor stars
• Observational Properties of the Metal-Poor Thick Disk of the Milky Way Galaxy and Insights into Its Origins
• APOGEE DR16: a multi-zone chemical evolution model for the Galactic disc based on MCMC methods
• Metal Abundances and Kinematics of Bright Metal-Poor Giants Selected from the LSE Survey: Implications for the Metal-Weak Thick Disk
• Stellar parametrization from Gaia RVS spectra
• The Pristine survey X: a large population of low-metallicity stars permeates the Galactic disk
• 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
• Evidence of a dynamically evolving Galactic warp
• NIHAO-UHD: The properties of MW-like stellar disks in high resolution cosmological simulations
• In the thick of it: metal-poor disc stars in RAVE
• Galactic Archaeology with asteroseismic ages. II. Confirmation of a delayed gas infall using Bayesian analysis based on MCMC methods
• Two chemically similar stellar overdensities on opposite sides of the plane of the Galaxy
• The Pristine Survey -- VI. The first three years of medium-resolution follow-up spectroscopy of Pristine EMP star candidates
• The relationship between mono-abundance and mono-age stellar populations in the Milky Way disk
• The Pristine survey VIII: The metallicity distribution function of the Milky Way halo down to the extremely metal-poor regime
• Reviving old controversies: is the early Galaxy flat or round? Investigations into the early phases of the Milky Way formation through stellar kinematics and chemical abundances
• Exploring the origin of low-metallicity stars in Milky Way-like galaxies with the NIHAO-UHD simulations
• Pristine IX: CFHT ESPaDOnS Spectroscopic Analysis of 115 Bright Metal-Poor Candidate Stars
• The Pristine survey III: Spectroscopic confirmation of an efficient search for extremely metal-poor stars
• The Century Survey Galactic Halo Project III: A Complete 4300 deg^2 Survey of Blue Horizontal Branch Stars in the Metal-Weak Thick Disk and Inner Halo
• Searching for the metal-weak thick disc in the solar neighbourhood
• Evolution of lithium in the Milky Way halo, discs and bulge
• Evidence of a thick disk rotation-metallicity correlation
• The Splash without a merger
• Exploring the Galaxy's halo and very metal-weak thick disk with SkyMapper and Gaia DR2
• Evidence for the Third Stellar Population in the Milky Way's Disk
• Exploring the Galactic Warp Through Asymmetries in the Kinematics of the Galactic Disk
• Testing General Relativity with Growth rate measurement from Sloan Digital Sky Survey III Baryon Oscillations Spectroscopic Survey galaxies
• A Blueprint for the Milky Way's Stellar Populations: The Power of Large Photometric and Astrometric Surveys
• Fluorine in the solar neighborhood: modelling the Galactic thick and thin discs
• Modelling the chemical evolution of Zr, La, Ce and Eu in the Galactic discs and bulge
• The chemodynamics of prograde and retrograde Milky Way stars
• Through thick and thin: Structure of the Galactic thick disc from extragalactic surveys
• Rotational signature of the Milky Way stellar halo
• Disk-Like Chemistry of the Triangulum-Andromeda Overdensity as Seen by APOGEE
• The Rotation-Metallicity Relation for the Galactic Disk as Measured in the Gaia DR1 TGAS and APOGEE Data
• A-type stars in the Canada-France Imaging Survey II. Tracing the height of the disc at large distances with Blue Stragglers
• Ancient Very Metal-Poor Stars Associated With the Galactic Disk in the H3 Survey
• The metal-rich halo component extended in z: a characterization with Gaia DR2 and APOGEE
• The Pristine survey II: a sample of bright stars observed with FEROS
• Cardinal kinematics: I. Rotation fields of the APOGEE Survey
• An empirical formula for the distribution function of a thin exponential disc
• Milky Way chemo-dynamics in the era of Gaia
• Evidence of a large scale positive rotation-metallicity correlation in the Galactic thick disk

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• The Pristine survey: XXV. The very metal-poor Galaxy: Chemodynamics through the follow-up of the Pristine-Gaia synthetic catalogue
• Chronology of our Galaxy from Gaia colour-magnitude diagram fitting (ChronoGal) II. Unveiling the formation and evolution of the kinematically selected Thick and Thin Discs
• The globular cluster system of the nearest Seyfert II galaxy Circinus
• A Very Metal-poor RR Lyrae Star with a Disk Orbit Found in the Solar Neighborhood
• The metal-poor tail of the APOGEE survey I. Uncovering [Fe/H] < -2.5 stars from the inner Galaxy to the Magellanic Clouds
• Detailed Abundance Determination of Metal-Poor Stars with X-Shooter I. Unusual Chemistry in Halo Stars
• The disturbed outer Milky Way disc
• An ancient system hidden in the Galactic plane?