Are the Formation and Abundances of Metal-Poor Stars the Result of Dust Dynamics?

Abstract

Large dust grains can fluctuate dramatically in their local density, relative to gas, in neutral, turbulent disks. Small, high-redshift galaxies (before reionization) represent ideal environments for this process. We show via simple arguments and simulations that order-of-magnitude fluctuations are expected in local abundances of large grains under these conditions. This can have important consequences for star formation and stellar abundances in extremely metal-poor stars. Low-mass stars could form in dust-enhanced regions almost immediately after some dust forms, even if the galaxy-average metallicity is too low for fragmentation to occur. The abundances of these 'promoted' stars may contain interesting signatures, as the CNO abundances (concentrated in large carbonaceous grains and ices) and Mg and Si (in large silicate grains) can be enhanced or fluctuate independently. Remarkably, otherwise puzzling abundance patterns of some metal-poor stars can be well-fit by standard core-collapse SNe yields, if we allow for fluctuating dust-to-gas ratios. We also show that the observed log-normal-like distribution of enhancements in these species agrees with our simulations. Moreover, we confirm Mg and Si are correlated in these stars, with abundance ratios similar to those in local silicate grains. Meanwhile [Mg/Ca], predicted to be nearly invariant from pure SNe yields, shows large enhancements as expected in the dust-promoted model, preferentially in the [C/Fe]-enhanced metal-poor stars. This suggests that (1) dust exists in second-generation star formation, (2) dust-to-gas ratio fluctuations occur and can be important for star formation, and (3) light element abundances of these stars may be affected by the chemistry of dust where they formed, rather than directly tracing nucleosynthesis.

13 pages, 6 figures, accepted to ApJ (replaced with published version)

References in corpus (44)

• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• The Density Probability Distribution in Compressible Isothermal Turbulence: Solenoidal versus Compressive Forcing
• Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
• Dust Formation and Survival in Supernova Ejecta
• Carbon-Enhanced Metal-Poor Star Frequencies in the Galaxy: Corrections for the Effect of Evolutionary Status on Carbon Abundances
• Fragmentation of star-forming clouds enriched with the first dust
• The relation between gas and dust in the Taurus Molecular Cloud
• Resolving the Formation of Protogalaxies. III. Feedback from the First Stars
• The First Galaxies: Assembly, Cooling and the Onset of Turbulence
• Segue 1: An Unevolved Fossil Galaxy from the Early Universe
• Resolving the Formation of Protogalaxies. II. Central Gravitational Collapse
• Rapid formation of large dust grains in the luminous supernova SN 2010jl
• TOPoS: II. On the bimodality of carbon abundance in CEMP stars. Implications on the early chemical evolution of galaxies
• Accurate, Meshless Methods for Magneto-Hydrodynamics
• An Elemental Assay of Very, Extremely, and Ultra Metal-Poor Stars
• The chemistry of population III supernova ejecta: II - The nucleation of molecular clusters as a diagnostic for dust in the early universe
• Stellar Archaeology -- Exploring the Universe with Metal-Poor Stars
• Shattering and coagulation of dust grains in interstellar turbulence
• Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence
• Is the Scaling of Supersonic Turbulence Universal?
• The Turbulent Dynamo in Highly Compressible Supersonic Plasmas
• Decoding the stellar fossils of the dusty Milky Way progenitors
• The Fundamentally Different Dynamics of Dust and Gas in Molecular Clouds
• Metal-Poor Stars Observed with the Magellan Telescope. III. New Extremely and Ultra Metal-Poor Stars from SDSS/SEGUE and Insights on the Formation of Ultra Metal-Poor Stars
• SD 1313-0019 -- Another second-generation star with [Fe/H] = -5.0, observed with the Magellan Telescope
• The first stars: CEMP--no stars and signatures of spinstars
• Faint Population III supernovae as the origin of the most iron-poor stars
• The properties of the 2175AA extinction feature discovered in GRB afterglows
• Stellar Yields of Rotating First Stars. I. Yields of Weak Supernovae and Abundances of Carbon-enhanced Hyper Metal Poor Stars
• The metal and dust yields of the first massive stars
• Modelling the observed properties of carbon-enhanced metal-poor stars using binary population synthesis
• Evidence for Large Grains in the Star-forming Filament OMC-2/3
• On the (in)variance of the dust-to-metals ratio in galaxies
• On Dust Extinction of Gamma-ray Burst Host Galaxies
• The extinction law inside the 30 Doradus nebula
• The origin of the most iron-poor star
• Constraining dust formation in high-redshift young galaxies
• Dust formation, evolution, and obscuration effects in the very high-redshift universe
• Can We Trust the Dust? Evidence of Dust Segregation in Molecular Clouds
• Kinematics of solid particles in a turbulent protoplanetary disc
• Particle splitting in smoothed particle hydrodynamics based on Voronoi diagram
• Evolution of dust content in galaxies probed by gamma-ray burst afterglows
• Dust Production Factories in the Early Universe: Formation of Carbon Grains in Red-supergiant Winds of Very Massive Population III Stars

Cited by in corpus (8)

• But What About... Cosmic Rays, Magnetic Fields, Conduction, & Viscosity in Galaxy Formation
• When Feedback Fails: The Scaling and Saturation of Star Formation Efficiency
• Ubiquitous Instabilities of Dust Moving in Magnetized Gas
• The Dynamics of Charged Dust in Magnetized Molecular Clouds
• The Resonant Drag Instability (RDI): Acoustic Modes
• Dust in the Wind with Resonant Drag Instabilities: I. The Dynamics of Dust-Driven Outflows in GMCs and HII Regions
• Gravitational Fragmentation of Extremely Metal-poor Circumstellar Discs
• Dust-Evacuated Zones Near Massive Stars: Consequences of Dust Dynamics on Star-forming Regions