s-Process Elements in the M Supergiant α Ori Original Research Article

We present new results on a study of the weak s-process elemental abundances in the M supergiant a Ori (M2Iab). We have conducted the abundance analysis through comparison of synthetic with observed spectra in the two infrared spectral regions 0.7 - 1.1 μm and 2.1 - 2.3 μm, where the molecular and atomic line densities are less than in the optical region and where many of the relevant elements have strong lines. Our results show that there has been weak s-process production occurring during the life of the star and among the s-process elements is Sr the most overabundant with 1.4 dex higher abundance than the sun. The abundance of Fe in α Ori is essentially solar. Other elements for which we have determined abundances are Rb, Y and Zr. We compare our results to nuclear evolutionary stellar model calculations and discuss their relevance.