Seeding the second star -- II. CEMP star formation enriched from faint supernovae

Abstract

Carbon-enhanced metal-poor (CEMP) stars are the living fossils holding records of chemical enrichment from early generations of stars. In this work, we perform a set of numerical simulations of the enrichment from a supernova (SN) of a first generation of metal-free (Pop III) star and the gravitational collapse of the enriched cloud, considering all relevant cooling/heating processes and chemical reactions as well as the growth of dust grains. We adopt faint SN models for the first time with progenitor masses $M_{\mathrm{PopIII}}=13$--$80{\mathrm{M}}_{⨀}$, which yield C-enhanced abundance patterns ($[C/Fe]=4.57$--$4.75$) through mixing and fallback of innermost layers of the ejecta. This model also considers the formation and destruction of dust grains. We find that the metals ejected by the SN can be partly re-accreted by the same dark matter minihalo, and carbon abundance of the enriched cloud $A(\mathrm{C})=3.80$--$5.06$ is lower than the abundance range of observed CEMP stars ($A(\mathrm{C})\gtrsim 6$) because the mass of the metals ejected by faint SNe is smaller than normal core-collapse SNe due to extensive fallback. We also find that cloud fragmentation is induced by gas cooling from carbonaceous grains for $M_{\mathrm{PopIII}}=13{\mathrm{M}}_{⨀}$ even with the lowest iron abundance $[Fe/H]\sim -9$. This leads to the formation of low-mass stars, and these ``giga metal-poor'' stars can survive until the present-day Universe and may be found by future observations.

19 pages, 14 figures, 3 tables, accepted for publication in MNRAS

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Cited by in corpus (10)

• The role of faint population III supernovae in forming CEMP stars in ultra-faint dwarf galaxies
• A Minimum Dilution Scenario for Supernovae and Consequences for Extremely Metal-Poor Stars
• Metal Mixing in Minihalos: The Descendants of Pair-Instability Supernovae
• How much metals did the first stars provide to the ultra-faint dwarfs?
• 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
• The energy distribution of the first supernovae
• Gravitational waves from mergers of Population III binary black holes: roles played by two evolution channels
• Can Population III stars be major origins of both merging binary black holes and extremely metal poor stars?
• Metal-Poor Stars Observed with the Southern African Large Telescope II. An Extended Sample
• Where are the extremely metal-poor stars in the Milky Way and Andromeda? Expectations from TNG50