The s-process enriched star HD 55496: origin from a globular cluster or from the tidal disruption of a dwarf galaxy?

Abstract

We present a new abundance analysis of HD 55496, previously known as a metal-poor barium star. We found that HD 55496 has a metallicity [Fe/H] $=-1.55$ and is s-process enriched. We find that HD 55496 presents four chemical peculiarities: (i) a Na-O abundance anti-correlation; (ii) it is aluminum rich; (iii) it is carbon poor for a s-process enriched star and (iv) the heavy 2${}^{nd}$ s-process peak elements, such as Ba, La, Ce, and Nd, present smaller abundances than the lighter s-process elements, such as Sr, Y and Zr, which is not usually observed among the chemically-peculiar binary stars at this metallicity. The heavy-element abundance pattern suggests that the main source of the neutrons is the ${}^{22}$Ne($\alpha$,n)${}^{25}$Mg reaction. Taken all these abundance evidence together into consideration, this strongly suggests that HD 55496 is a "second generation of globular cluster star" formed from gas already strongly enriched in s-process elements and now is a field halo object. Our dynamical analysis, however, indicates that the past encounter probabilities with the known globular clusters is very small ($\le 6\%$). This evidence, together with the fact of having a retrograde motion, points to a halo intruder possibly originated from the tidal disruption of a dwarf galaxy.

References in corpus (49)

• The 'Forbidden' Abundance of Oxygen in the Sun
• Galactic Chemical Evolution: Hydrogen Through Zinc
• The Chemical Compositions of Galactic Disk F and G Dwarfs
• Global survey of star clusters in the Milky Way II. The catalogue of basic parameters
• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• Properties of stellar generations in Globular Clusters and relations with global parameters
• Abundances and Kinematics of Field Halo and Disk Stars I: Observational Data and Abundance Analysis
• A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
• Nucleosynthesis and mixing on the Asymptotic Giant Branch. III. Predicted and observed s-process abundances
• Evolution, nucleosynthesis and yields of AGB stars at different metallicities (III): intermediate mass models, revised low mass models and the ph-FRUITY interface
• Pulkovo Compilation of Radial Velocities for 35495 Hipparcos Stars in a Common System
• Extremely Metal-Poor Stars. VIII. High-Resolution, High-Signal-To-Noise Analysis of Five Stars with [Fe/H] < -3.5
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy
• Improved Laboratory Transition Probabilities for Neutral Chromium and Re-determination of the Chromium Abundance for the Sun and Three Stars
• First Stars II. Elemental abundances in the extremely metal-poor star CS 22949--037: A diagnostic of early massive supernovae
• Na-O Anticorrelation And HB I. The Na-O anticorrelation in NGC 2808
• Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-process Rich, Metal-Poor Stars, and Rare Earth Lab Data
• Local Stellar Kinematics from RAVE Data: I. Local Standard of Rest
• Stellar Archaeology: a Keck Pilot Program on Extremely Metal- Poor Stars From the Hamburg/ESO Survey. III. The Lead (Pb) Star HE 0024-2523
• Stellar Archaeology: a Keck Pilot Program on Extremely Metal-Poor Stars from the Hamburg/ESO Survey. II. Abundance Analysis
• More lead stars
• First stars IV.CS 29497-030: Evidence for operation of the s-process at very low metallicity
• Improved Ni I log(gf) Values and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937
• CS 30322-023: an ultra metal-poor TP-AGB star?
• New analysis of the two carbon-rich stars CS 22948-27 and CS 29497-34 : binarity and neutron-capture elements
• CS22964-161: A Double-Lined Carbon- and s-Process-Enhanced Metal-Poor Binary Star
• Oxygen abundances in low- and high-alpha field halo stars and the discovery of two field stars born in globular clusters
• Chemical tagging in the SDSS-III/APOGEE survey: new identifications of halo stars with globular cluster origins
• Chemical tagging of three distinct populations of red giants in the globular cluster NGC 6752
• Atypical Mg-poor Milky Way field stars with globular cluster second-generation like chemical patterns
• Exploring Halo Substructure with Giant Stars: Substructure in the Local Halo as Seen in the Grid Giant Star Survey Including Extended Tidal Debris from Omega Centauri
• Chemical abundances and kinematics of barium stars
• Oxygen Overabundance in the Extremely Iron-Poor Star CS29498-043
• Discovery of a Metal-Poor Field Giant with a Globular Cluster Second-Generation Abundance Pattern
• The s process in AGB stars as constrained by a large sample of Barium stars
• When binaries keep track of recent nucleosynthesis: The Zr - Nb pair in extrinsic stars as an s-process diagnostic
• Potassium in globular cluster stars: comparing normal clusters to the peculiar cluster NGC 2419
• The completeness-corrected rate of stellar encounters with the Sun from the first Gaia data release
• Spectroscopic analysis of the two subgiant branches of the globular cluster NGC1851
• On metal-deficient barium stars and their link with yellow symbiotic stars
• Chemical analysis of giant stars in the young open cluster NGC 3114
• Detailed Abundances of 15 Stars in the Metal-Poor Globular Cluster NGC 4833
• The Na-O anticorrelation in horizontal branch stars. V. NGC 6723
• C, N and O abundances in red clump stars of the Milky Way
• Chemical analysis of CH stars - II: atmospheric parameters and elemental abundances
• The Na-O anticorrelation in horizontal branch stars. IV. M22
• CD-62\degree1346: an extreme halo or hypervelocity CH~star?
• A chemical signature from fast-rotating low-metallicity massive stars: ROA 276 in omega Centauri
• High-resolution spectroscopic observations of the new CEMP-s star CD-50${}^{\circ }$776

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• Low-mass low-metallicity AGB stars as an efficient i-process site explaining CEMP-rs stars
• Chemodynamics of newly identified giants with globular cluster like abundance patterns in the bulge, disk, and halo of the Milky Way
• Galactic ArchaeoLogIcaL ExcavatiOns (GALILEO) I. An updated census of APOGEE N-rich giants across the Milky Way
• Jurassic: A Chemically Anomalous Structure in the Galactic Halo
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