$s$-Process in Massive Carbon-Enhanced Metal-Poor Stars

Abstract

Observations suggest that the interstellar medium (ISM) might have been highly enriched in carbon at very early times. We explore nucleosynthesis in massive carbon-enhanced metal-poor (CEMP) stars of $12$--$40{\mathrm{M}}_{\odot }$ formed from such an ISM with $[\mathrm{Fe}]\le -2$. We find substantial production of elements heavier than Fe, mostly up to Sr, by the weak \textsl{s}-process in stars with initial abundances of $[\mathrm{CNO}]\gtrsim -1.5$. Even heavier elements, up to Ba, can be produced for $[\mathrm{CNO}]\gtrsim -0.5$. The efficiency of this \textsl{s}-process is sensitive to the initial enhancement of C (or more generally, CNO) and mass of the star, with the yield increasing approximately linearly with the initial Fe abundance. The \textsl{s}-process in CEMP stars of $\gtrsim 20{\mathrm{M}}_{\odot }$ with $[\mathrm{CNO}]\gtrsim -1.5$ can be an important source for heavy elements in the Early Galaxy.

arXiv comment6 pages, 2 figures, and 3 tables, Accepted for publication in MNRAS

References in corpus (16)

• Nucleosynthesis in Massive Stars With Improved Nuclear and Stellar Physics
• Nucleosynthesis and Evolution of Massive Metal-Free Stars
• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• The Stellar Abundances for Galactic Archeology (SAGA) Database - Compilation of the Characteristics of Known Extremely Metal-Poor Stars
• The early star generations: the dominant effect of rotation on the CNO yields
• Variations in the Abundance Pattern of Extremely Metal-poor Stars and Nucleosynthesis in Population III Supernovae
• $s$-process production in rotating massive stars at solar and low metallicities
• Non-standard s process in low metallicity massive rotating stars
• The s process in massive stars at low metallicity. Effect of primary N14 from fast rotating stars
• Observational Constraints on First-Star Nucleosynthesis. I. Evidence for Multiple Progenitors of CEMP-no Stars
• The role of binaries in the enrichment of the early Galactic halo. III. Carbon-enhanced metal-poor stars -- CEMP-s stars
• Carbon-enhanced metal-poor stars: the most pristine objects?
• Abundance Profiling of Extremely Metal-Poor Stars and Supernova Properties in the Early Universe
• The Most Metal-Poor Stars. III. The Metallicity Distribution Function and CEMP Fraction
• Measurement of the reaction O-17(α,n)Ne-20 and its impact on the s process in massive stars
• First direct measurement of resonance strengths in 17O(α, γ)21Ne

Cited by in corpus (4)

• New \textsl{s}-process Mechanism in Rapidly-Rotating Massive Pop II Stars
• The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates
• Chemical analysis of two extremely metal-poor stars HE 2148-2039 and HE 2155-2043
• HD 222925: a New Opportunity to Explore the Astrophysical and Nuclear Conditions of r-process Sites