The s process in massive stars at low metallicity. Effect of primary N14 from fast rotating stars

Abstract

The goal of this paper is to analyze the impact of a primary neutron source on the s-process nucleosynthesis in massive stars at halo metallicity. Recent stellar models including rotation at very low metallicity predict a strong production of primary N14. Part of the nitrogen produced in the H-burning shell diffuses by rotational mixing into the He core where it is converted to Ne22 providing additional neutrons for the s process. We present nucleosynthesis calculations for a 25 Msun star at [Fe/H] = -3, -4, where in the convective core He-burning about 0.8 % in mass is made of primary Ne22. The usual weak s-process shape is changed by the additional neutron source with a peak between Sr and Ba, where the s-process yields increase by orders of magnitude with respect to the yields obtained without rotation. Iron seeds are fully consumed and the maximum production of Sr, Y and Zr is reached. On the other hand, the s-process efficiency beyond Sr and the ratio Sr/Ba are strongly affected by the amount of Ne22 and by nuclear uncertainties, first of all by the Ne22(alpha,n)Mg25 reaction. Finally, assuming that Ne22 is primary in the considered metallicity range, the s-process efficiency decreases with metallicity due to the effect of the major neutron poisons Mg25 and Ne22. This work represents a first step towards the study of primary neutron source effect in fast rotating massive stars, and its implications are discussed in the light of spectroscopic observations of heavy elements at halo metallicity.

Accepted for publication in ApJ Letters, 11 pages, 2 figures, 1 table

References in corpus (5)

• Nucleosynthetic signatures of the first stars
• First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
• Very low metallicity massive star models: Pre-SN evolution and primary nitrogen production
• A strong case for fast stellar rotation at very low metallicities
• Nucleosynthesis in the Early Galaxy

Cited by in corpus (61)

• Segue 1: An Unevolved Fossil Galaxy from the Early Universe
• The elemental composition of the Sun III. The heavy elements Cu to Th
• Chemical evolution with rotating massive star yields II. A new assessment of the solar s- and r- process components
• High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey
• The role of neutron star mergers in the chemical evolution of the Galactic halo
• The 12C + 12C reaction and the impact on nucleosynthesis in massive stars
• Exploring the Origin of Lithium, Carbon, Strontium and Barium with four new Ultra Metal-Poor Stars
• Nucleosynthesis Modes in the High-Entropy-Wind of Type II Supernovae: Comparison of Calculations with Halo-Star Observations
• Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process
• How many nucleosynthesis processes exist at low metallicity?
• New insights on Ba over-abundance in open clusters. Evidence for the intermediate neutron-capture process at play?
• The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis. II. Early chemical enrichment
• The origin of s-process isotope heterogeneity in the solar protoplanetary disk
• High-resolution abundance analysis of red giants in the globular cluster NGC 6522
• The s Process and Beyond
• Heavy elements in Globular Clusters: the role of AGB stars
• Galactic Chemical Evolution: the Impact of the 13C-pocket Structure on the s-process Distribution
• The Chemical Composition of the Galactic Bulge and Implications for its Evolution
• The R-Process Alliance: Chemo-Dynamically Tagged Groups of Halo $r$-Process-Enhanced Stars Reveal a Shared Chemical-Evolution History
• Are some CEMP-s stars the daughters of spinstars?
• Measurement of the reaction O-17(α,n)Ne-20 and its impact on the s process in massive stars
• Zero and extremely low metallicity rotating massive stars: evolution, explosion, and nucleosynthesis up to the heaviest nuclei
• The R-Process Alliance: The Peculiar Chemical Abundance Pattern of RAVE J183013.5-455510
• The COMBS survey I: Chemical Origins of Metal-Poor Stars in the Galactic Bulge
• Constraints on stellar rotation from the evolution of Sr and Ba in the Galactic halo
• The Impact of Black Hole Formation on Population Averaged Supernova Yields
• The R-Process Alliance: Abundance Universality among Some Elements at and between the First and Second R-Process Peaks
• Stellar winds and metal enrichment from fast-rotating Population III stars
• The p-process in exploding rotating massive stars
• NGC 6522: A typical globular cluster in the Galactic bulge without signatures of rapidly rotating Population III stars
• Neutron-capture elements in dwarf galaxies II: Challenges for the s- and i-processes at low metallicity
• Rapidly rotating Population III stellar models as a source of primary nitrogen
• First direct measurement of resonance strengths in 17O(α, γ)21Ne
• The s-Process Enrichment of the Globular Clusters M4 and M22
• Enrichment of the Galactic disc with neutron capture elements: Sr
• Origin of metals in old Milky Way halo stars based on GALAH and Gaia
• Galactic Chemical Evolution of Radioactive Isotopes with an s-process Contribution
• The formation of the Milky Way halo and its dwarf satellites: A NLTE-1D abundance analysis. V. The Sextans galaxy
• Inferring the velocity of early massive stars from the abundances of extremely metal-poor stars
• Heavy element abundances in P-rich stars: A new site for the s-process?
• A strong neutron burst in jet-like supernovae of spinstars
• A chemical signature from fast-rotating low-metallicity massive stars: ROA 276 in omega Centauri
• The impact of ${}^{17}$O$+\alpha$ reaction rate uncertainties on the s-process in rotating massive stars
• Time evolution of Ce as traced by APOGEE using giant stars observed with the Kepler, TESS and K2 missions
• Massive stars evolution with new C12+C12 nuclear reaction rate -- the core carbon-burning phase
• The Pristine Inner Galaxy Survey (PIGS) IX. The largest detailed chemical analysis of very metal-poor stars in the Sagittarius dwarf galaxy
• Chemical Evolution of R-process Elements in Stars (CERES). III. Chemical abundances of neutron capture elements from Ba to Eu
• Signature of a massive rotating metal-poor star imprinted in the Phoenix stellar stream
• Unlocking the mystery of Sr synthesis in the early Galaxy through analysis of barium isotopes in very metal-poor stars
• The s process in massive stars, a benchmark for neutron capture reaction rates
• Does the chemical signature of TYC 8442-1036-1 originate from a rotating massive star that died in a faint explosion?
• Constraints on key ${}^{17}$O($\alpha ,\gamma$)${}^{21}$Ne resonances and impact on the weak s-process
• The neutron-capture and alpha-elements abundance ratios scatter in old stellar populations. Cosmological simulations of the stellar halo
• The complex stellar system M 22: constraining the chemical enrichment from AGB stars using magnesium isotope ratios
• Chemical Evolution in Nuclear Stellar Discs
• Modelling the chemical evolution of the Milky Way
• Probing Massive Star Nucleosynthesis with Data on Metal-Poor Stars and the Solar System
• Impact of the latest 22Ne+α reaction rates on nucleosynthesis in massive stars and galactic chemical evolution
• Galactic chemical evolution: The role of the first stars
• The Two-infall Model Revisited: Constraints on Milky Way Bulge Assembly from >30,000 Galactic Chemical Evolution Models and Machine Learning
• UVES analysis of red giants in the bulge globular cluster NGC 6522