Hypervelocity Star Candidates in the SEGUE G & K Dwarf Sample

Abstract

We present 20 candidate hypervelocity stars from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) G and K dwarf samples. Previous searches for hypervelocity stars have only focused on large radial velocities; in this study we also use proper motions to select the candidates. We determine the hypervelocity likelihood of each candidate by means of Monte Carlo simulations, considering the significant errors often associated with high proper motion stars. We find that nearly half of the candidates exceed their escape velocities with at least 98% probability. Every candidate also has less than a 25% chance of being a high-velocity fluke within the SEGUE sample. Based on orbits calculated using the observed six-dimensional positions and velocities, few, if any, of these candidates originate from the Galactic center. If these candidates are truly hypervelocity stars, they were not ejected by interactions with the Milky Way's supermassive black hole. This calls for a more serious examination of alternative hypervelocity-star ejection scenarios.

8 pages, 5 figures, published in ApJ, this version includes all figures as intended

References in corpus (56)

• The Sloan Digital Sky Survey: Technical Summary
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
• The USNO-B Catalog
• Local Kinematics and the Local Standard of Rest
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III
• SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20
• The Multi-Object, Fiber-Fed Spectrographs for SDSS and the Baryon Oscillation Spectroscopic Survey
• Astrometric Calibration of the Sloan Digital Sky Survey
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• The RAVE Survey: Constraining the Local Galactic Escape Speed
• The SEGUE Stellar Parameter Pipeline. I. Description and Initial Validation Tests
• The spatial structure of mono-abundance sub-populations of the Milky Way disk
• Ejection of hypervelocity stars by the (binary) black hole(s) in the Galactic center
• HST/NICMOS Observations of Massive Stellar Clusters Near the Galactic Center
• Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo
• Properties of spherical galaxies and clusters with an NFW density profile
• The SEGUE Stellar Parameter Pipeline. II. Validation with Galactic Globular and Open Clusters
• Galactic Rotation and Solar Motion from Stellar Kinematics
• The SEGUE Stellar Parameter Pipeline. III. Comparison with High-Resolution Spectroscopy of SDSS/SEGUE Field Stars
• Assessing the Milky Way Satellites Associated with the Sagittarius Dwarf Spheroidal Galaxy
• Interaction of massive black hole binaries with their stellar environment: I. Ejection of hypervelocity stars
• A First Constraint on the Thick Disk Scale Length: Differential Radial Abundances in K Giants at Galactocentric Radii 4, 8, and 12 kpc
• The Milky Way Tomography with SDSS: III. Stellar Kinematics
• HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star
• US 708 - An unbound hyper-velocity subluminous O star
• The SEGUE Stellar Parameter Pipeline. IV. Validation with an Extended Sample of Galactic Globular and Open Clusters
• Sgr A* Companion S0-2: A Probe of Very High-Mass Star Formation
• The SEGUE Stellar Parameter Pipeline. V. Estimation of Alpha-Element Abundance Ratios From Low-Resolution SDSS/SEGUE Stellar Spectra
• A Short Scale Length for the α-Enhanced Thick Disk of the Milky Way: Evidence from Low-Latitude SEGUE Data
• The M31 Velocity Vector. I. Hubble Space Telescope Proper Motion Measurements
• The Stellar Metallicity Distribution Function of the Galactic Halo from SDSS Photometry
• On the origin of high-velocity runaway stars
• Shaping the Globular Cluster Mass Function by Stellar-Dynamical Evaporation
• An Alternative Origin for Hypervelocity Stars
• New Tests for Disruption Mechanisms of Star Clusters: The Large and Small Magellanic Clouds
• MMT Hypervelocity Star Survey
• Galactic Globular and Open Clusters in the Sloan Digital Sky Survey. II. Test of Theoretical Stellar Isochrones
• Cool White Dwarfs in the Sloan Digital Sky Survey
• The Metallicity Distribution Functions of SEGUE G and K dwarfs: Constraints for Disk Chemical Evolution and Formation
• Does the dwarf galaxy system of the Milky Way originate from Andromeda?
• Turbovelocity Stars: Kicks Resulting From the Tidal Disruption of Solitary Stars
• MMT Hypervelocity Star Survey. II. Five New Unbound Stars
• HD 271791: An Extreme Supernova Runaway B Star Escaping from the Galaxy
• S-stars in the Galactic center and hypervelocity stars in the Galactic halo: two faces of the tidal breakup of stellar binaries by the central massive black hole?
• Improved Astrometry and Photometry for the Luyten Catalog. I. Bright Stars
• Hypervelocity Stars from the Andromeda Galaxy
• Proper Motion Catalog From SDSS \intersect USNO-B
• SEGUE-2 Limits on Metal-Rich Old-Population Hypervelocity Stars In the Galactic Halo
• Old-Population Hypervelocity Stars from the Galactic Center: Limits from the SDSS
• Kinematics in galactic tidal tails - A source for Hypervelocity stars?
• Completeness of USNO-B for High Proper-Motion Stars
• Investigation of the errors in SDSS proper-motion measurements using samples of quasars
• Identifying Star Streams in the Milky Way Halo
• A Star in the M31 Giant Stream: the Highest Negative Stellar Velocity Known

Cited by in corpus (38)

• MMT Hypervelocity Star Survey III: A Complete Survey of Faint B-type Stars in the Northern Milky Way Halo
• The fastest unbound star in our Galaxy ejected by a thermonuclear supernova
• Outflows and complex stellar kinematics in SDSS star forming galaxies
• Maximum speed of hypervelocity stars ejected from binaries
• Revisiting hypervelocity stars after Gaia DR2
• Kinematics and Host-Galaxy Properties Suggest a Nuclear Origin for Calcium-Rich Supernova Progenitors
• Relativistic effects on tidal disruption kicks of solitary stars
• Predicted Space Motions for Hypervelocity and Runaway Stars: Proper Motions and Radial Velocities for the GAIA Era
• High velocity stars from close interaction of a globular cluster and a super massive black hole
• The interaction of core-collapse supernova ejecta with a companion star
• Characterizing the High-Velocity Stars of RAVE: The Discovery of a Metal-Rich Halo Star Born in the Galactic Disk
• High velocity stars from the interaction of a globular cluster and a massive black hole binary
• Constraining Milky Way mass with Hypervelocity Stars
• Predicting the hypervelocity star population in Gaia
• Gaia DR3 in 6D: The search for fast hypervelocity stars and constraints on the Galactic Centre environment
• Core-Collapse Supernovae in Binaries as the Origin of Galactic Hyper-Runaway Stars
• The Nearest High-Velocity Stars Revealed by LAMOST Data Release 1
• New nearby hypervelocity stars and their spatial distribution from Gaia DR2
• Warm Dust around Cool Stars: Field M Dwarfs with WISE 12 or 22 Micron Excess Emission
• Chemical abundances in a high velocity RR Lyrae star near the bulge
• On the origins of extreme velocity stars as revealed by large-scale Galactic surveys
• Candidate hypervelocity stars of spectral type G and K revisited
• Red Runaways: Hypervelocity Stars, Hills Ejecta and Other Outliers in the F-M Star Regime
• Comparing hypervelocity star populations from the Large Magellanic Cloud and the Milky Way
• Constraints on the Galactic Centre environment from \textit{Gaia} hypervelocity stars III: Insights on a possible companion to Sgr A*
• Constraints on the Galactic Centre environment from Gaia hypervelocity stars II: The evolved population
• The luminosity function of quasars by the Principle of Maximum Entropy
• Intermediate-Mass Black Holes in binary-rich star clusters
• Transits Probabilities Around Hypervelocity and Runaway Stars
• Hypervelocity star candidates from Gaia DR2 and DR3 proper motions and parallaxes
• Red Runaways II: Low mass Hills stars in SDSS Stripe 82
• Constraints on the origins of hypervelocity stars: velocity distribution, mergers and star-formation history
• Candidate Hypervelocity Red Clump Stars in the Galactic Bulge Found Using the VVV and Gaia Surveys
• HSC16aayt: Slowly evolving interacting transient rising for more than 100 days
• Detecting Stars at the Galactic Centre via Synchrotron Emission
• Three New Late-type Hypervelocity Star Candidates from Gaia DR2 with Refined Selection Criteria
• Searching for new Hypervelocity Stars with Gaia DR3 and VLT/FORS2 Spectroscopy
• Nearby Low-Mass Hypervelocity Stars