Timeline for ²⁶Al injection in a dense collected shell around a massive star, starting approximately 10 Myr after the birth of stellar generation #1 and lasting  ~t_⋆. The upper part of the figure represents the time line of the central massive star of panel c in Fig. 1. In the middle part, the timeline of the ²⁶Al production and injection (arrows) is shown. Aluminum-26 is present in the wind some 10⁵ yr after the star formation and absent when products of helium-burning appear at the surface (WC-type star) since ²⁶Al is destroyed in helium-burning cores. It is present while the star explodes as an SN. Aluminum-26 injection in the shell lasts during the whole collection phase and is assumed to stop during the collapse phase lasting a time Δ_C  ~  10⁵ yr. The lower part represents the timeline of the collected shell, which eventually collapses to produce a protoSun and a protoplanetary disk in which most CAIs form.