Injection of freshly synthesized ^(41)Ca in the early solar nebula by an asymptotic giant branch star

Abstract

We show that ejecta from the envelope of one asymptotic giant branch star of M ~ 3 M_☉ may account for many of the short-lived nuclei in the early solar system and also for the recent evidence of the presence of ^(41)Ca (t_(41) = 1.50 x 10^5 yr) in early solar nebular condensates. This would require that the injection into the protosolar molecular cloud took place within a narrow time interval of (5-7) x 10^5 yr before the formation of the solar system. If true, this places extremely tight constraints on the whole process of injection mixing and collapse. The timescales for both ^(41)Ca and ^(26)AI require that the placental medium be a dense molecular cloud (2 x 10^3-8 x 10^3 H cm^(-3)). If the observed residual ^(41)Ca is instead produced by a proton bombardment mechanism within the early solar system, similar to what appears necessary to explain ^(53)Mn, then the time interval is relaxed but would still be (1-2) x 10^6 yr from consideration of ^(26)Al.