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arXiv · astro-ph/9511142

The Production of Ti44 and Co60 in Supernova

F. X. Timmes·S. E. Woosley·D. H. Hartmann·R. D. Hoffman
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Abstract

The production of the radioactive isotopes $^{44}$Ti and $^{60}$Co in all types of supernovae is examined and compared to observational constraints including Galactic $γ$--ray surveys, measurements of the diffuse 511 keV radiation, $γ$--ray observations of Cas A, the late time light curve of SN 1987A, and isotopic anomalies found in silicon carbide grains in meteorites. The (revised) line flux from $^{44}$Ti decay in the Cas A supernova remnant reported by COMPTEL on the Compton Gamma-Ray Observatory is near the upper bound expected from our models. The necessary concurrent ejection of $^{56}$Ni would also imply that Cas A was a brighter supernova than previously thought unless extinction in the intervening matter was very large. Thus, if confirmed, the reported amount of $^{44}$Ti in Cas A provides very interesting constraints on both the supernova environment and its mechanism. The abundances of $^{44}$Ti and $^{60}$Co ejected by Type II supernovae are such that gamma-radiation from $^{44}$Ti decay SN 1987A could be detected by a future generation of gamma-ray telescopes and that the decay of $^{60}$Co might provide an interesting contribution to the late time light curve of SN 1987A and other Type II supernovae. To produce the solar $^{44}$Ca abundance and satisfy all the observational constraints, nature may prefer at least the occasional explosion of sub-Chandrasekhar mass white dwarfs as Type Ia supernovae. Depending on the escape fraction of positrons due to $^{56}$Co made in all kinds of Type Ia supernovae, a significant fraction of the steady state diffuse 511 keV emission may arise from the annihilation of positrons produced during the decay of $^{44}$Ti to $^{44}$Ca. The Ca and Ti isotopic anomalies in pre-solar grains confirm the production of $^{44}$Ti in supernovae and that

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F. X. Timmes, S. E. Woosley, D. H. Hartmann, R. D. Hoffman. 1995-11-29. The Production of Ti44 and Co60 in Supernova. https://doi.org/10.1086/177323

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