Discovery of a nitrogen-enhanced mildly metal-poor binary system: Possible evidence for pollution from an extinct AGB Star

Abstract

We report the serendipitous discovery of a nitrogen-rich, mildly metal-poor ([Fe/H]=-1.08) giant star in a single-lined spectroscopic binary system found in the SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) survey, Data Release 14 (DR14). Previous work has assumed that the two percent of halo giants with unusual elemental abundances have been evaporated from globular clusters, but other origins for their abundance signatures, including binary mass transfer, must also be explored. We present the results of an abundance re-analysis of the APOGEE-2 high-resolution near-infrared spectrum of 2M12451043+1217401 with the Brussels Automatic Stellar Parameter (BACCHUS) automated spectral analysis code, and re-derive manually the main element families, namely the light elements (C, N), elements (O, Mg, Si), iron-peak element (Fe), \textit{s}-process element (Ce), and the light odd-Z element (Al). Our analysis confirm the N-rich nature of 2M12451043+1217401, which has a [N/Fe] ratio of $+0.69$, and shows that the abundances of C and Al are slightly discrepant from that of a typical mildly metal-poor RGB star, but exhibit Mg, Si, O and \textit{s}-process abundances (Ce) of typical field stars. We also detect a particularly large variability in its radial velocity over the period of the APOGEE-2 observations, and the most likely orbit fit to the radial velocity data has a period of $730.89\pm 106.86$ days, a velocity semi-amplitude of $9.92\pm 0.14$ km s${}^{-1}$, and an eccentricity of $\sim 0.1276\pm 0.1174$, which support the hypothesis of a binary companion, and that has probably been polluted by a now-extinct AGB star.

arXiv commentAccepted for publication in A&A, 13 pages, 8 figures, 7 tables

References in corpus (51)

• Gaia Data Release 2. Summary of the contents and survey properties
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• Astrophysics Source Code Library
• ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline
• Multiple Stellar Populations in Globular Clusters
• 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
• VLT/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies: I. Nucleosynthesis and Abundance Ratios
• The Data Reduction Pipeline for the Apache Point Observatory Galactic Evolution Experiment
• A new implementation of the infrared flux method using the 2MASS catalogue
• Target Selection for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Evolution, nucleosynthesis and yields of AGB stars at different metallicities (III): intermediate mass models, revised low mass models and the ph-FRUITY interface
• Target Selection for the SDSS-IV APOGEE-2 Survey
• StarHorse: A Bayesian tool for determining stellar masses, ages, distances, and extinctions for field stars
• The Payne: self-consistent ab initio fitting of stellar spectra
• A holistic approach to carbon-enhanced metal-poor stars
• The elemental composition of the Sun III. The heavy elements Cu to Th
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy
• Lifting the Dusty Veil With Near- and Mid-Infrared Photometry: I. Description and Applications of the Rayleigh-Jeans Color Excess Method
• Binarity in Carbon-Enhanced Metal-Poor stars
• The Bar and Spiral Structure Legacy (BeSSeL) Survey: Mapping the Milky Way with VLBI Astrometry
• Building the Galactic halo from globular clusters: evidence from chemically unusual red giants
• New H-band Stellar Spectral Libraries for the SDSS-III/APOGEE survey
• Chemical Abundances in Field Red Giants from High-Resolution H-Band Spectra using the APOGEE Spectral Linelist
• Light-element Abundance Variations in the Milky Way Halo
• An accurate and self-consistent chemical abundance catalogue for the APOGEE/Kepler sample
• A Search for Nitrogen-Enhanced Metal-Poor Stars
• A homogeneous analysis of globular clusters from the APOGEE survey with the BACCHUS code. I. The Northern clusters
• APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy
• Chemical tagging in the SDSS-III/APOGEE survey: new identifications of halo stars with globular cluster origins
• Atypical Mg-poor Milky Way field stars with globular cluster second-generation like chemical patterns
• Discovery of a Metal-Poor Field Giant with a Globular Cluster Second-Generation Abundance Pattern
• Constraints of the physics of low-mass AGB stars from CH and CEMP stars
• The Gaia-ESO Survey: A globular cluster escapee in the Galactic halo
• Chemodynamics of newly identified giants with globular cluster like abundance patterns in the bulge, disk, and halo of the Milky Way
• The Relationship Between Globular Cluster Mass, Metallicity, and Light Element Abundance Variations
• More nitrogen rich B-type stars in the SMC cluster, NGC 330
• Detecting outliers and learning complex structures with large spectroscopic surveys - a case study with APOGEE stars
• The Gaia-ESO Survey: low-alpha element stars in the Galactic Bulge
• A cyclic bipolar wind in the interacting binary V393 Scorpii
• H-band discovery of additional Second-Generation stars in the Galactic Bulge Globular Cluster NGC 6522 as observed by APOGEE and Gaia
• Searching for tidal tails around $\omega$ Centauri using RR Lyrae Stars
• CN Anomalies in the Halo System and the Origin of Globular Clusters in the Milky Way
• RAVE stars tidally stripped/ejected from $\omega$ Centauri globular cluster
• Close encounters involving RAVE stars beyond the 47 Tucanae tidal radius
• A peculiar interacting Be star binary in the Small Magellanic Cloud
• The SMC B-type supergiant AzV322: a g-mode pulsator with a circumstellar disc

Cited by in corpus (22)

• Nitrogen enhancements 440 Myr after the Big Bang: super-solar N/O, a tidal disruption event or a dense stellar cluster in GN-z11?
• Close Binary Companions to APOGEE DR16 Stars: 20,000 Binary-star Systems Across the Color-Magnitude Diagram
• Aluminum Enhanced Metal-Poor Stars buried in the Inner Galaxy
• Axion Astrophysics
• Discovery of a new stellar sub-population residing in the (inner) stellar halo of the Milky Way
• Dynamical Orbital classification of selected N-rich stars with \textit{Gaia} DR2 astrometry
• VVV CL001: Likely the Most Metal-Poor Surviving Globular Cluster in the Inner Galaxy
• The enigmatic globular cluster UKS~1 obscured by the bulge: \textit{H}-band discovery of nitrogen-enhanced stars
• Galactic ArchaeoLogIcaL ExcavatiOns (GALILEO) I. An updated census of APOGEE N-rich giants across the Milky Way
• APOGEE discovery of a chemically atypical star disrupted from NGC 6723 and captured by the Milky Way bulge
• APOGEE spectroscopic evidence for chemical anomalies in dwarf galaxies: The case of M~54 and Sagittarius
• Discovery of a large population of Nitrogen-Enhanced stars in the Magellanic Clouds
• Jurassic: A Chemically Anomalous Structure in the Galactic Halo
• On the Chemical and Kinematic Consistency Between N-rich Metal-poor Field Stars and Enriched Populations in Globular Clusters
• CAPOS: The bulge Cluster APOgee Survey III. Spectroscopic Tomography of Tonantzintla 2
• Galactic ArchaeoLogIcaL ExcavatiOns (GALILEO) II. t-SNE Portrait of Local Fossil Relics and Structures
• The search for extratidal star candidates around Galactic globular clusters NGC 2808, NGC 6266, and NGC 6397 with {\textit{Gaia}} DR2 astrometry
• A Nitrogen-Enhanced Metal-Poor star discovered in the globular cluster ESO280-SC06
• Near-infrared chemical abundances of stars in the Sculptor dwarf galaxy
• CAPOS: The bulge Cluster APOGEE Survey VI. Characterizing multiple stellar populations and chemical abundances in the bulge globular cluster NGC 6569
• LAMOST J045019.27+394758.7, with peculiar abundances of N, Na, V, Zn, is possibly a Sculptor dwarf galaxy escapee
• Not all nitrogen-rich field stars originate from globular clusters