The chemical abundance pattern of the extremely metal-poor thin disk star 2MASS J1808-5104 and its origins

Abstract

We present a high-resolution ($R\sim 35,000$), high signal-to-noise ($S/N=350$) Magellan/MIKE spectrum of the bright extremely metal-poor star 2MASS~J1808$-$5104. We find [Fe/H] = $-$4.01 (spectroscopic LTE stellar parameters), [Fe/H] = $-$3.8 (photometric stellar parameters), [Fe/H] = $-$3.7 (spectroscopic NLTE stellar parameters). We measured a carbon-to-iron ratio of $\mbox{[C/Fe]}= 0.38$ from the CH G-band. J1808$-$5104 is thus not carbon-enhanced, contrary to many other stars with similarly low iron abundances. We also determine, for the first time, a barium abundance ($\mbox{[Ba/Fe]} =-0.78$), and obtain a significantly reduced upper limit for the nitrogen abundance ([N/Fe]$<-0.2$). J1808$-$5104 has low ratio of $\mbox{[Sr/Ba]}=-0.17$, which is consistent with that of stars in ultra-faint dwarf galaxies. We also fit the abundance pattern of J1808$-$5104 with nucleosynthesis yields from a grid of Population\,III supernova models. There is a good fit to the abundance pattern which suggests J1808$-$5104 originated from gas enriched by a single massive supernova with a high explosion energy of E $=10\times 10^{51}$\,erg and a progenitor stellar mass of M$=29.5$\,M${}_{\odot }$. Interestingly, J1808$-$5104 is a member of the Galactic thin disk, as confirmed by our detailed kinematic analysis and calculated stellar actions and velocities. Finally, we also established the orbital history of J1808$-$5104 using our time-dependent Galactic potential the \texttt{ORIENT}. J1808$-$5104 appears to have a stable quasi-circular orbit and been largely confined to the thin disk. This unique orbital history, the star's very old age ($\sim 13.5$\,Gyr), and the low [C/Fe] and [Sr/Ba] ratios suggest that J1808$-$5104 may have formed at the earliest epoch of the hierarchical assembly of the Milky Way, and it is most likely associated with the primordial thin disk.

References in corpus (42)

• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• galpy: A Python Library for Galactic Dynamics
• Nucleosynthetic signatures of the first stars
• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
• An extremely primitive halo star
• Carbon-Enhanced Metal-Poor Star Frequencies in the Galaxy: Corrections for the Effect of Evolutionary Status on Carbon Abundances
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• HE 0557-4840 - Ultra-Metal-Poor and Carbon-Rich
• NLTE abundances of Mn in a sample of metal-poor stars
• Probing the Formation of the First Low-Mass Stars with Stellar Archaeology
• The Chemical Evolution of the Draco Dwarf Spheroidal Galaxy
• Observational Constraints on First-Star Nucleosynthesis. I. Evidence for Multiple Progenitors of CEMP-no Stars
• HE 1327-2326, an unevolved star with [Fe/H]<-5.0. II. New 3D-1D corrected abundances from a VLT/UVES spectrum
• An Elemental Assay of Very, Extremely, and Ultra Metal-Poor Stars
• Stellar Archaeology -- Exploring the Universe with Metal-Poor Stars
• Non-LTE aluminium abundances in late-type stars
• High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey
• First stars X. The nature of three unevolved Carbon-Enhanced Metal-Poor stars
• CS 30322-023: an ultra metal-poor TP-AGB star?
• Decoding the stellar fossils of the dusty Milky Way progenitors
• linemake: An Atomic and Molecular Line List Generator
• Carbon-Enhanced Metal-Poor Stars: Relics from the Dark Ages
• Spectroscopic analysis of metal-poor stars from LAMOST: early results
• Chemical Abundance Analysis of the Extremely Metal-Poor Star HE 1300+0157
• Evidence for an aspherical Population III supernova explosion inferred from the hyper metal-poor star HE1327-2326
• Observational Constraints on First-Star Nucleosynthesis. II. Spectroscopy of an Ultra Metal-Poor CEMP-no Star
• Chemical Signatures of the First Supernovae in the Sculptor Dwarf Spheroidal Galaxy
• Zero-metallicity hypernova uncovered by an ultra metal-poor star in the Sculptor dwarf spheroidal galaxy
• Pristine IX: CFHT ESPaDOnS Spectroscopic Analysis of 115 Bright Metal-Poor Candidate Stars
• Exploring the Galaxy's halo and very metal-weak thick disk with SkyMapper and Gaia DR2
• Supernova dust formation and the grain growth in the early universe: The critical metallicity for low-mass star formation
• G64-12 and G64-37 are Carbon-Enhanced Metal-Poor Stars
• WHT follow-up observations of extremely metal-poor stars identified from SDSS and LAMOST
• Metal-poor stars observed with the automated planet finder telescope. I. Discovery of five carbon-enhanced metal-poor stars from LAMOST
• The R-Process Alliance: The Peculiar Chemical Abundance Pattern of RAVE J183013.5-455510
• New Fe I level energies and line identifications from stellar spectra
• The low Sr/Ba ratio on some extremely metal-poor stars
• New ultra metal-poor stars from SDSS: follow-up GTC medium-resolution spectroscopy
• Detailed Iron-Peak Element Abundances in Three Very Metal-Poor Stars
• Ancient Very Metal-Poor Stars Associated With the Galactic Disk in the H3 Survey
• Be and O in the ultra metal-poor dwarf 2MASS J18082002-5104378: The Be-O correlation

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