The high velocity stars in the Local Stellar Halo from Gaia and LAMOST

Abstract

Based on the first Gaia data release and spectroscopy from the LAMOST Data Release 4, we study the kinematics and chemistry of the local halo stars. The halo stars are identified kinematically with a relative speed of at least 220 km s${}^{-1}$ with respect to the local standard of rest. In total, 436 halo stars are identified. From this halo sample, 16 high velocity (HiVel) stars are identified. We studied the metallicity and [$\alpha$/Fe] distribution of these HiVel stars. Though most of HiVel stars are metal-poor, there are several stars that have metallicity above $-0.5$ dex. To understand the origin of high velocity stars, we evolve the trajectory of the star backwards along the orbit in our adopted Galaxy potential model to determine the orbital parameters and assess whether the star could have originated in the Galactic center. We found that some high velocity stars could have originated from the Galactic center, but other stars were probably kicked up from the Galactic disk.

arXiv comment9 pages, 6 figures, accepted for publication in ApJ

References in corpus (58)

• The Gaia mission
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• MILES: A Medium resolution INT Library of Empirical Spectra
• The New Galaxy: Signatures of its Formation
• GAIA: Composition, Formation and Evolution of the Galaxy
• The mass distribution and gravitational potential of the Milky Way
• Stellar Chemical Signatures And Hierarchical Galaxy Formation
• The RAVE Survey: Constraining the Local Galactic Escape Speed
• Gaia Data Release 1: Astrometry - one billion positions, two million proper motions and parallaxes
• Two distinct halo populations in the solar neighborhood. Evidence from stellar abundance ratios and kinematics
• LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) The survey science plan
• The age structure of stellar populations in the solar vicinity. Clues of a two-phase formation history of the Milky Way disk
• A database of high and medium-resolution stellar spectra
• Ejection of hypervelocity stars by the (binary) black hole(s) in the Galactic center
• Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo
• The Dual Origin of Stellar Halos
• The ELODIE archive
• The RAVE survey: the Galactic escape speed and the mass of the Milky Way
• Cosmological simulations of the formation of the stellar haloes around disc galaxies
• Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters
• Formation and Evolution of the Disk System of the Milky Way: [alpha/Fe] Ratios and Kinematics of the SEGUE G-Dwarf Sample
• Thin disc, Thick Disc and Halo in a Simulated Galaxy
• Gaia reveals a metal-rich in-situ component of the local stellar halo
• HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star
• US 708 - An unbound hyper-velocity subluminous O star
• The LAMOST Stellar Parameter Pipeline at Peking University --- LSP3
• MMT Hypervelocity Star Survey III: A Complete Survey of Faint B-type Stars in the Northern Milky Way Halo
• Formation of In Situ Stellar Haloes in Milky Way-Mass Galaxies
• Estimating distances from parallaxes. III. Distances of two million stars in the Gaia DR1 catalogue
• The fastest unbound star in our Galaxy ejected by a thermonuclear supernova
• The Formation of a Disk Galaxy within a Growing Dark Halo
• Hypervelocity Stars. I. The Spectroscopic Survey
• On the origin of high-velocity runaway stars
• An Alternative Origin for Hypervelocity Stars
• MMT Hypervelocity Star Survey
• Companion stars of Type Ia supernovae and hypervelocity stars
• Maximum speed of hypervelocity stars ejected from binaries
• LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC): the second release of value-added catalogues
• Element Ratios and the Formation of the Stellar Halo
• Producing type Iax supernovae from a specific class of helium-ignited WD explosions?
• Runaway and hypervelocity stars in the Galactic halo: Binary rejuvenation and triple disruption
• The First Hypervelocity Star from the LAMOST Survey
• Heated Disc Stars in the Stellar Halo
• MMT Hypervelocity Star Survey. II. Five New Unbound Stars
• On the kinematics of a runaway Be star population
• The relation between chemical abundances and kinematics of the Galactic disc with RAVE
• Characterizing the High-Velocity Stars of RAVE: The Discovery of a Metal-Rich Halo Star Born in the Galactic Disk
• A Dipole on the Sky: Predictions for Hypervelocity Stars from the Large Magellanic Cloud
• High velocity stars from the interaction of a globular cluster and a massive black hole binary
• Runaway Stars, Hypervelocity Stars, and Radial Velocity Surveys
• On the spatial distribution and the origin of hypervelocity stars
• Discovery of two new hypervelocity stars from the LAMOST spectroscopic surveys
• Hypervelocity Stars from the Andromeda Galaxy
• Metal-poor hypervelocity star candidates from the Sloan Digital Sky Survey
• Supernovae in the Central Parsec: A Mechanism for Producing Spatially Anisotropic Hypervelocity Stars
• Reconstructing the Accretion History of the Galactic Stellar Halo from Chemical Abundance Ratio Distributions
• The spatial and velocity distributions of hypervelocity stars

Cited by in corpus (16)

• A nearby repeating fast radio burst in the direction of M81
• Overview of the LAMOST survey in the first decade
• Chemical and Kinematic Properties of the Galactic Disk from the LAMOST and Gaia Sample Stars
• 591 high velocity stars in the Galactic halo selected from LAMOST DR7 and Gaia DR2
• Nearby high-speed stars in Gaia DR2
• New nearby hypervelocity stars and their spatial distribution from Gaia DR2
• Stars made in outflows may populate the stellar halo of the Milky Way
• Cool stars in the Galactic Center as seen by APOGEE: M giants, AGB stars and supergiant stars/candidates
• Local stellar formation history from the 40 pc white dwarf sample
• The Triangulum Extended (TREX) Survey: The Stellar Disk Dynamics of M33 as a Function of Stellar Age
• Detectability of Wandering Intermediate-Mass Black Holes in the Milky Way Galaxy from Radio to X-rays
• The origin of high velocity stars from Gaia and LAMOST
• HST Low Resolution Stellar Library
• A possible surviving companion of the SN Ia in the Galactic SNR G272.2-3.2
• A Large Catalog of DA White Dwarf Characteristics Using SDSS and Gaia Observations
• OGLE-2017-BLG-1038: A Possible Brown-dwarf Binary Revealed by Spitzer Microlensing Parallax