J01020100-7122208: an accreted evolved blue straggler that wasn't ejected from a supermassive black hole

Abstract

J01020100-7122208 is a star whose origin and nature still challenges us. It was first believed to be a yellow super giant ejected from the Small Magellanic Cloud, but it was more recently claimed to be a red giant accelerated by the Milky Way's central black hole. In order to unveil its nature, we analysed photometric, astrometric and high resolution spectroscopic observations to estimate the orbit, age, and 16 elemental abundances. Our results show that this star has a retrograde and highly-eccentric orbit, $e=0.914_{-0.020}^{+0.016}$. Correspondingly, it likely crossed the Galactic disk at $550\mathrm{pc}$ from the Galactic centre. We obtained a spectroscopic mass and age of $1.09\pm 0.10$ $M_{\odot }$ and $4.51\pm 1.44$ Gyr respectively. Its chemical composition is similar to the abundance of other retrograde halo stars. We found that the star is enriched in europium, having [Eu/Fe] = 0.93 $\pm$ 0.24, and is more metal-poor than reported in the literature, with [Fe/H] = -1.30 $\pm$ 0.10. This information was used to conclude that J01020100-7122208 is likely not a star ejected from the central black of the Milky Way or from the Small Magellanic Cloud. Instead, we propose that it is simply a halo star which was likely accreted by the Milky Way in the distant past but its mass and age suggest it is probably an evolved blue straggler.

17 pages, 9 Figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

References in corpus (78)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Gaia mission
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• Multimodal nested sampling: an efficient and robust alternative to MCMC methods for astronomical data analysis
• X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue
• Nucleosynthesis in Chandrasekhar Mass Models for Type Ia Supernovae and Constraints on Progenitor Systems and Burning-Front Propagation
• 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
• Gaia Early Data Release 3: The astrometric solution
• Star Formation Histories, Abundances and Kinematics of Dwarf Galaxies in the Local Group
• The mass distribution and gravitational potential of the Milky Way
• Co-formation of the Galactic disc and the stellar halo
• Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
• Galactic Chemical Evolution: Hydrogen Through Zinc
• Galactic chemical evolution: Carbon through Zinc
• Gaia Early Data Release 3: Photometric content and validation
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• Optimal Techniques in Two-dimensional Spectroscopy: Background Subtraction for the 21st Century
• 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 GALAH+ Survey: Third Data Release
• Two distinct halo populations in the solar neighborhood. Evidence from stellar abundance ratios and kinematics
• Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• Vertical waves in the solar neighbourhood in Gaia DR2
• Modern stellar spectroscopy caveats
• Gaia FGK Benchmark Stars - Metallicity
• Gaia FGK Benchmark Stars: Effective temperatures and surface gravities
• The RAVE survey: the Galactic escape speed and the mass of the Milky Way
• APOGEE Data Releases 13 and 14: Data and Analysis
• Multiple retrograde substructures in the Galactic halo: A shattered view of Galactic history
• SkyMapper Southern Survey: Second Data Release (DR2)
• Gas Dynamics in the Milky Way: Second Pattern Speed and Large-Scale Morphology
• Young [$\alpha$/Fe]-enhanced stars discovered by CoRoT and APOGEE: What is their origin?
• The Role of Type Ia Supernovae in Chemical Evolution I: Lifetime of Type Ia Supernovae and Galactic Supernova Rates
• Accuracy and precision of industrial stellar abundances
• Europium production: neutron star mergers versus core-collapse supernovae
• Gaia FGK benchmark stars: abundances of alpha and iron-peak elements
• Ages and kinematics of chemically selected, accreted Milky Way halo stars
• The Gaia FGK Benchmark Stars - High resolution spectral library
• The Fall of a Giant. Chemical evolution of Enceladus, alias the Gaia Sausage
• Abundances for metal-poor stars with accurate parallaxes II. alpha-elements in the halo
• Atomic and Molecular Data for Optical Stellar Spectroscopy
• The Great Escape: Discovery of a nearby 1700 km/s star ejected from the Milky Way by Sgr A*
• The CatWISE Preliminary Catalog: Motions from $WISE$ and $NEOWISE$ Data
• Chronologically dating the early assembly of the Milky Way
• The Correlation Between Mixing Length and Metallicity on the Giant Branch: Implications for Ages in the Gaia Era
• Two distinct halo populations in the solar neighborhood. III. Evidence from stellar ages and orbital parameters
• The SkyMapper-Gaia RVS view of the Gaia-Enceladus-Sausage -- an investigation of the metallicity and mass of the Milky Way's last major merger
• Testing the Asteroseismic Mass Scale Using Metal-Poor Stars Characterized with APOGEE and Kepler
• Origin of the excess of high-energy retrograde stars in the Galactic halo
• Galactic Archaeology with asteroseismology and spectroscopy: Red giants observed by CoRoT and APOGEE
• The Age of the Milky Way Inner Halo
• Binary stars in the Galactic thick disc
• Cannibals in the thick disk: the young $\alpha -$rich stars as evolved blue stragglers
• Element Ratios and the Formation of the Stellar Halo
• Elevated r-process enrichment in Gaia Sausage and Sequoia
• Effective temperature determinations of late-type stars based on 3D non-LTE Balmer line formation
• Yellow Supergiants in the Small Magellanic Cloud (SMC): Putting Current Evolutionary Theory to the Test
• Gaia FGK Benchmark stars: Opening the black box of stellar element abundance determination
• The age of the Milky Way halo stars from the Sloan Digital Sky Survey
• Unveiling systematic biases in 1D LTE excitation-ionisation balance of Fe for FGK stars. A novel approach to determination of stellar parameters
• GRACES observations of young [alpha/Fe]-rich stars
• Gaia FGK Benchmark Stars: New Candidates At Low-Metallicities
• Origin of $\alpha$-rich young stars: clues from C, N and O
• Light Elements in the Universe
• The Fastest Travel Together: Chemical Tagging of the Fastest Stars in Gaia DR2 to the Stellar Halo
• Joint constraints on the Galactic dark matter halo and Galactic Centre from hypervelocity stars
• On the Relative Ages of the $\alpha$-Rich and $\alpha$-Poor Stellar Populations in the Galactic Halo
• The chemodynamics of prograde and retrograde Milky Way stars
• Chemical abundances in a high velocity RR Lyrae star near the bulge
• Optical high-resolution spectroscopy of 14 young $\alpha$-rich stars
• A Runaway Yellow Supergiant Star in the Small Magellanic Cloud
• A Runaway Giant in the Galactic Halo

Cited by in corpus (2)

• Cannibals in the thick disk II -- Radial-velocity monitoring of the young alpha-rich stars
• The accreted Galaxy: An overview of TESS metal-poor accreted stars candidates