Testing Rotational Mixing Predictions with New Boron Abundances in Main Sequence B-type Stars

Abstract

(Abridged) New boron abundances for seven main-sequence B-type stars are determined from HST STIS spectroscopy around the BIII 2066A line. Boron abundances provide a unique and critical test of stellar evolution models that include rotational mixing since boron is destroyed in the surface layers of stars through shallow mixing long before other elements are mixed from the stellar interior through deep mixing. Boron abundances range from 12+log(B/H) = 1.0 to 2.2. The boron abundances are compared to the published values of their stellar nitrogen abundances (all have 12+log(N/H) < 7.8, i.e., they do not show significant CNO-mixing) and to their host cluster ages (4 to 16 Myr) to investigate the predictions from models of massive star evolution with rotational mixing effects (Heger & Langer 2000). Only three stars (out of 34) deviate from the model predictions, including HD36591, HD205021, and HD30836. These three stars suggest that rotational mixing could be more efficient than currently modelled at the highest rotation rates.

10 figures, 7 tables; accepted for publication in the Astrophysical Journal

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• Presupernova Evolution of Rotating Massive Stars II: -- Evolution of the Surface Properties
• The VLT-FLAMES Survey of Massive Stars: Observations in the Galactic Clusters NGC 3293, NGC 4755 and NGC 6611
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Cited by in corpus (15)

• Pre-Supernova Evolution of Massive Single and Binary Stars
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• Nitrogen enrichment, boron depletion and magnetic fields in slowly-rotating B-type dwarfs
• Massive star models with magnetic braking
• Constraints on rotational mixing from surface evolution of light elements in massive stars
• Shear mixing in stellar radiative zones I. Effect of thermal diffusion and chemical stratification
• 3D hydrodynamic simulations of massive main-sequence stars. I. Dynamics and mixing of convection and internal gravity waves
• The magneto-rotational instability in massive stars
• Boron depletion in Galactic early B-type stars reveals two different main sequence star populations
• Lithium in coalesced non-compact stars
• A Search for Boron in Damped Lyα Systems
• Nucleosynthesis from massive stars 50 years after B2FH
• Intriguing Revelations from Lithium, Beryllium, and Boron
• Boron Abundances in the Galactic Disk