NLTE determination of the aluminium abundance in a homogeneous sample of extremely metal-poor stars

Abstract

Aims: Aluminium is a key element to constrain the models of the chemical enrichment and the yields of the first supernovae. But obtaining precise Al abundances in extremely metal-poor (EMP) stars requires that the non-LTE effects be carefully taken into account. Methods: The NLTE profiles of the blue resonance aluminium lines have been computed in a sample of 53 extremely metal-poor stars with a modified version of the program MULTI applied to an atomic model of the Al atom with 78 levels of Al I and 13 levels of Al II, and compared to the observations. Results: With these new determinations, all the stars of the sample show a ratio Al/Fe close to the solar value: [Al/Fe] =-0.06 +- 0.10 with a very small scatter. These results are compared to the models of the chemical evolution of the halo using different models of SN II and are compatible with recent computations. The sodium-rich giants are not found to be also aluminium-rich and thus, as expected, the convection in these giants only brings to the surface the products of the Ne-Na cycle.

To be published on A&A

References in corpus (5)

• Galactic chemical evolution: Carbon through Zinc
• Fast rotating massive stars and the origin of the abundance patterns in galactic globular clusters
• First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
• First stars VII. Lithium in extremely metal poor dwarfs
• NLTE determination of the sodium abundance in a homogeneous sample of extremely metal-poor stars

Cited by in corpus (2)

• Evolution of the Barium abundance in the early Galaxy from a NLTE analysis of the Ba lines in a homogeneous sample of EMP stars
• Chemical Analysis of Five Red Giants in the Globular Cluster M10 (NGC 6254)