Radioactive ²⁶Al from the Scorpius-Centaurus association

The origin of the short-lived isotope ²⁶AL in the Galaxy has been traced to nucleosynthesis in massive stars through diffuse emission. First detected by COMPTEL through low spatial and energy resolution, the fingerprint of the evolutionary stage and mass of the originators have been open questions. This paper presents a study using the INTEGRAL gamma-ray observatory of a subgroup in the Sco-Cen association, a massive OB association at a distance of about 150 pc. The ²⁶Al mass is about 10^-4 M_⊙ and they derive a radial velocity of 135±75 km/s from the Doppler shift of the line. The ejection from stars with ages of a few Myr is identified as the source.