SDSS J102915.14+172927.9: Revisiting the chemical pattern

Abstract

Context: The small- to intermediate-mass ($M<0.8M_{\odot }$), most metal-poor stars that formed in the infancy of the Universe are still shining today in the sky. They are very rare, but their discovery and investigation brings new knowledge on the formation of the first stellar generations. Aims: SDSS J102915.14+172927.9 is one of the most metal-poor star known to date. Since no carbon can be detected in its spectrum, a careful upper limit is important, both to classify this star and to distinguish it from the carbon-enhanced stars that represent the majority at these metallicities. Methods: We undertook a new observational campaign to acquire high-resolution UVES spectra. The new spectra were combined with archival spectra in order to increase the signal-to-noise ratio. From the combined spectrum, we derived abundances for seven elements (Mg, Si, Ca, Ti, Fe, Ni, and a tentative Li) and five significant upper limits (C, Na, Al, Sr, and Ba). Results: The star has a carbon abundance A(C) <4.68 and therefore is not enhanced in carbon, at variance with the majority of the stars at this Fe regime, which typically show A(C)> 6.0. A feature compatible with the Li doublet at 670.7 nm is tentatively detected. Conclusions: The upper limit on carbon implies $Z<1.915\times 10^{-6}$, more than 20 times lower than the most iron-poor star known. Therefore, the gas cloud out of which the star was formed did not cool via atomic lines but probably through dust. Fragmentation of the primordial cloud is another possibility for the formation of a star with a metallicity this low.

References in corpus (60)

• Gaia Data Release 3: Summary of the content and survey properties
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• Local Kinematics and the Local Standard of Rest
• galpy: A Python Library for Galactic Dynamics
• First stars V - Abundance patterns from C to Zn and supernova yields in the early Galaxy
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• The chemical make-up of the Sun: A 2020 vision
• A stellar relic from the early Milky Way
• Thermal and Fragmentation Properties of Star-forming Clouds in Low-metallicity Environments
• The Formation of the First Low-Mass Stars From Gas With Low Carbon and Oxygen Abundances
• First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
• The Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data
• Simulations of stellar convection with CO5BOLD
• A single low-energy, iron-poor supernova as the source of metals in the star SMSS J 031300.36-670839.3
• NLTE line formation of Fe for late-type stars. I. Standard stars with 1D and <3D> model atmospheres
• The Updated BaSTI Stellar Evolution Models and Isochrones: I. Solar Scaled Calculations
• Formation of the First Stars
• An extremely primitive halo star
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• CH in stellar atmospheres: an extensive linelist
• The First Galaxies: Chemical Enrichment, Mixing, and Star Formation
• Probing the Formation of the First Low-Mass Stars with Stellar Archaeology
• The updated BaSTI stellar evolution models and isochrones: II. alpha-enhanced calculations
• TOPoS: II. On the bimodality of carbon abundance in CEMP stars. Implications on the early chemical evolution of galaxies
• Gaia Data Release 3: External calibration of BP/RP low-resolution spectroscopic data
• The First Population II Stars Formed in Externally Enriched Mini-halos
• A primordial star in the heart of the Lion
• Four-hundred Very Metal-Poor Stars Studied with LAMOST and Subaru. II. Elemental abundances
• Tracing the formation of the Milky Way through ultra metal-poor stars
• Non-local thermodynamic equilibrium stellar spectroscopy with 1D and <3D> models - I. Methods and application to magnesium abundances in standard stars
• The Pristine Survey IV: Approaching the Galactic metallicity floor with the discovery of an ultra metal-poor star
• The formation of the extremely primitive star SDSS J102915+172927 relies on dust
• MyGIsFOS: an automated code for parameter determination and detailed abundance analysis in cool stars
• Reviving old controversies: is the early Galaxy flat or round? Investigations into the early phases of the Milky Way formation through stellar kinematics and chemical abundances
• A NLTE line formation for neutral and singly-ionised titanium in model atmospheres of the reference A-K stars
• Back to the Lithium Plateau with J0023+0307 with [Fe/H]<-6
• On the formation of very metal-poor stars: The case of SDSS J1029151+172927
• X-Shooter GTO: evidence for a population of extremely metal-poor, alpha-poor stars
• Ultra metal-poor stars: Spectroscopic determination of stellar atmospheric parameters using iron Non-LTE line abundances
• Dust grain growth and the formation of the extremely primitive star SDSS J102915+172927
• An in-depth spectroscopic examination of molecular bands from 3D hydrodynamical model atmospheres I. Formation of the G-band in metal-poor dwarf stars
• Discovery of a thin lithium plateau among metal-poor red giant branch stars
• The chemical signature of surviving Population III stars in the Milky Way
• Young giants of intermediate mass Evidence of rotation and mixing
• NLTE analysis of the methylidyne radical (CH) molecular lines in metal-poor stellar atmospheres
• The Pristine survey XIV: chemical analysis of two ultra-metal-poor stars
• Raising the observed metallicity floor with a 3D non-LTE analysis of SDSS J102915.14+172927.9
• An empirical recipe for inelastic hydrogen-atom collisions in non-LTE calculations
• The formation of the primitive star SDSS J102915+172927: effect of the dust mass and the grain-size distribution
• Probing the early Milky Way with GHOST spectra of an extremely metal-poor star in the Galactic disk
• Espresso observations of HE 0107$-$5240 and other CEMP-no stars with $[Fe/H]\le -4.5$
• Possible Evidence for Metal Accretion onto the Surfaces of Metal-Poor Main-Sequence Stars
• High-speed stars. II. An unbound star, young stars, bulge metal-poor stars, and Aurora candidates
• An investigation of the formation and line properties of MgH in 3D hydrodynamical model stellar atmospheres
• The extremely low metallicity star SDSS J102915+172927: a subgiant scenario
• High speed stars: III. Detailed abundances and binary nature of the extreme speed star GHS143
• Implications of time-dependent molecular chemistry in metal-poor dwarf stars

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• Discovery of an $[Fe/H]\sim -4.8$ Star in $Gaia$ XP Spectra
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