Formation of carbon-enhanced metal-poor stars as a consequence of inhomogeneous metal mixing

Abstract

We present a novel scenario for the formation of carbon-enhanced metal-poor (CEMP) stars. Carbon enhancement at low stellar metallicities is usually considered a consequence of faint or other exotic supernovae. An analytical estimate of cooling times in low-metallicity gas demonstrates a natural bias, which favours the formation of CEMP stars as a consequence of inhomogeneous metal mixing: carbon-rich gas has a shorter cooling time and can form stars prior to a potential nearby pocket of carbon-normal gas, in which star formation is then suppressed due to energetic photons from the carbon-enhanced protostars. We demonstrate that this scenario provides a natural formation mechanism for CEMP stars from carbon-normal supernovae, if inhomogeneous metal mixing provides carbonicity differences of at least one order of magnitude separated by >10pc. In our fiducial (optimistic) model, 8% (83%) of observed CEMP-no stars ([Ba/Fe]<0) can be explained by this formation channel. This new scenario may change our understanding of the first supernovae and thereby our concept of the first stars. Future 3D simulations are required to assess the likelihood of this mechanism to occur in typical high-redshift galaxies.

7 pages, 5 figures, published in ApJL, summary in Figure 1

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Cited by in corpus (18)

• Four-hundred Very Metal-Poor Stars Studied with LAMOST and Subaru. II. Elemental abundances
• Public Release of A-SLOTH: Ancient Stars and Local Observables by Tracing Halos
• The role of faint population III supernovae in forming CEMP stars in ultra-faint dwarf galaxies
• The chemical signature of jet-driven hypernovae
• Origin of the CEMP-no Group Morphology in the Milky Way
• Implications of inhomogeneous metal mixing for stellar archaeology
• Stellar winds and metal enrichment from fast-rotating Population III stars
• Chemo-Dynamically Tagged Groups of CEMP Stars in the Halo of the Milky Way. I. Untangling the Origins of CEMP-$s$ and CEMP-no Stars
• Origin of metals in old Milky Way halo stars based on GALAH and Gaia
• Inception of a first quasar at cosmic dawn
• The stochastic enrichment of Population II stars
• Photoevaporation of Minihalos during Cosmic Reionization: Primordial and Metal-Enriched Halos
• Formation of Pop II star clusters in the aftermath of a pair instability supernova
• Does the structure of Pop III supernova ejecta affect the elemental abundance of extremely metal-poor stars?
• A Carbon-enhanced Lyman Limit System: Signature of the First Generation of Stars?
• A second-generation star in a relic dwarf galaxy
• Carbon measurements in two ultra-faint dwarf galaxies: Grus II and Tucana IV
• Towards model-free stellar chemical abundances. Potential applications in the search for chemically peculiar stars in large spectroscopic surveys