2004/07/08 by J. C. Higdon, R. E. Lingenfelter, R. E. Rothschild
Physics and Astronomy · #Astro and Planetary Science #Gamma-ray bursts and supernovae #Nuclear physics research studies #astro-ph
paper · pdf · doi:10.1086/423616
published as Astrophys.J. 611 (2004) L29-L32 · Accepted for publication in Astrophysical Journal Letters, 611,10 August 2004
arxiv created 2004/07/08 · openalex publication_date 2004/07/12 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
The origin of the long-lived (1.07 Myr mean life) radioactive 26 Al, which has been observed in the Galactic interstellar medium from its 1.809 MeV decay gamma-ray line emission, has been a persistent problem for over 20 years. Wolf-Rayet (W-R) winds were thought to be the most promising source, but their calculated 26 Al yields are not consistent with recent analyses of the 1.809 MeV emission from the nearest W-R star and nearby OB associations. The expected 26 Al yield from the W-R star exceeds, by as much as a factor of 3, that set by the 2 σ upper limit on the 1.809 MeV emission, while the W-R yields in the OB associations are only about of that required by the 1.809 MeV emission. We suggest that a solution to these problems may lie in 26 Al from a previously ignored source: explosive nucleosynthesis in the core-collapse Type Ib/c supernovae (SNe Ib/c) of W-R stars that have lost most of their mass to close binary companions. Recent nucleosynthetic calculations of SNe Ib/c suggest that their 26 Al yields depend very strongly on the final pre-SN mass of the W-R star and that those with final masses around 6-8 M ☉ are expected to produce as much as 10 -2 M ☉ of 26 Al per SN. Such binary SNe Ib/c make up only a small fraction of the current SNe Ib/c and only about 1% of all Galactic core-collapse SNe. But they appear to be such prolific sources that the bulk of the present 26 Al in the Galaxy may come from just a few hundred close binary SNe Ib/c, and the intense 1.809 MeV emission from nearby OB associations may come from just one or two such SNe. More extensive SN Ib/c calculations of the 26 Al yields versus pre-SN mass are clearly needed to test this possibility.