Self-consistent Conditions for 26Al Injection into a Protosolar Disk from a Nearby Supernova

Abstract

The early solar system contained a short-lived radionuclide, 26Al (its half-life time t 1/2 = 0.7 Myr). The decay energy of 26Al is thought to have controlled the thermal evolution of planetesimals and, possibly, the water contents of planets. Many hypotheses have been proposed for the origin of 26Al in the solar system. One of the possible hypotheses is the “disk injection scenario”: when the protoplanetary disk of the solar system had already formed, a nearby (<1 pc) supernova injected radioactive material directly into the disk. Such a 26Al injection hypothesis has been tested so far with limited setups for disk structure and supernova distance, which have treated disk disruption and 26Al injection separately. Here, we revisit this problem, to investigate whether there are self-consistent conditions under which the surviving disk radius can receive enough 26Al to account for the abundance in the early solar system. We also consider a range of disk masses and structures, 26Al yields from supernova, and a large dust mass fraction η d. We find that 26Al yields of supernova are required as ≳2.1×10−3M⊙(ηd/0.2)−1 , which are challenging to achieve with the known possible 26Al ejection and dust mass fraction ranges. Furthermore, we find that even if the above conditions are met, the supernova flow changes the disk temperature, which may not be consistent with the solar system record. Our results place a strong constraint on the disk injection scenario. Rather, we suggest that the fresh 26Al of the early solar system must have been synthesized/injected in other ways.