The first stars: a classification of CEMP-no stars

Abstract

We propose and apply a new classification for the CEMP-no stars, which are "carbon-enhanced metal-poor" stars with no overabundance of s-elements and with [Fe/H] generally inferior or equal to -2.5. This classification is based on the changes in abundances for the elements and isotopes involved in the CNO, Ne-Na, and Mg-Al nuclear cycles. These abundances change very much owing to successive back and forth mixing motions between the He- and H-burning regions in massive stars (the "source stars" responsible for the chemical enrichment of the CEMP-no stars). The wide variety of the ratios [C/Fe], 12C/13C, [N/Fe], [O/Fe], [Na/Fe], [Mg/Fe], [Al/Fe], [Sr/Fe], and [Ba/Fe], which are the main characteristics making the CEMP-no and low s stars so peculiar, is described well in terms of the proposed nucleosynthetic classification. We note that the [(C+N+O)/Fe] ratios significantly increase for lower values of [Fe/H]. The classification of CEMP-no stars and the behavior of [(C+N+O)/Fe] support the presence, in the first stellar generations of the Galaxy, of fast-rotating massive stars experiencing strong mixing and mass loss (spinstars). This result has an impact on the early chemical and spectral evolution of the Galaxy.

10 pages, 7 figures, 2 tables, accepted for publication in Astronomy and Astrophysics

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Cited by in corpus (23)

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• Pop III $\text{i}$-process Nucleosynthesis and the Elemental Abundances of SMSS J0313-6708 and the Most Iron-Poor Stars
• Galactic Archeology with the AEGIS Survey: The Evolution of Carbon and Iron in the Galactic Halo
• Abundances of carbon-enhanced metal-poor stars as constraints on their formation
• Supernova dust yields: the role of metallicity, rotation, and fallback
• Convective H-He Interactions in Massive Population III Stellar Evolution Models
• The Most Metal-Poor Stars. V. The CEMP-no Stars in 3D and Non-LTE
• The Pristine survey -- XII: Gemini-GRACES chemo-dynamical study of newly discovered extremely metal-poor stars in the Galaxy
• Origin of the CEMP-no Group Morphology in the Milky Way
• Spectroscopic study of CEMP-(s & r/s) stars- Revisiting classification criteria and formation scenarios, highlighting i-process nucleosynthesis
• Constraints on CEMP-no progenitors from nuclear astrophysics
• 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
• Identification of a Group III CEMP-no Star in the Dwarf Spheroidal Galaxy Canes Venatici I
• Pre-supernova mixing in CEMP-no source stars
• Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. III. Dynamically Tagged Groups and Chemodynamical Properties
• Inferring the velocity of early massive stars from the abundances of extremely metal-poor stars
• Evidence for multiple nucleosynthetic processes from carbon enhanced metal-poor stars in the Carina dwarf spheroidal galaxy
• Chemical composition of two bright extremely metal-poor stars from the SDSS MARVELS pre-survey
• Explaining the ${}^{12}\text{C}{/}^{13}\text{C}$ ratio in the Galactic halo: the contribution from shell mergers in primordial massive stars
• Chemodynamical study of two CEMP-no stars from the Hamburg/ESO Survey
• Probing the nucleosynthetic contribution of low-metallicity, low-mass star companions of CEMP stars
• Does the chemical signature of TYC 8442-1036-1 originate from a rotating massive star that died in a faint explosion?