English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The production of the radioactive isotopes $^{44}$Ti and $^{60}$Co in alltypes of supernovae is examined and compared to observational constraintsincluding Galactic $\gamma$--ray surveys, measurements of the diffuse 511 keVradiation, $\gamma$--ray observations of Cas A, the late time light curve of SN1987A, and isotopic anomalies found in silicon carbide grains in meteorites.The (revised) line flux from $^{44}$Ti decay in the Cas A supernova remnantreported by COMPTEL on the Compton Gamma-Ray Observatory is near the upperbound expected from our models. The necessary concurrent ejection of $^{56}$Niwould also imply that Cas A was a brighter supernova than previously thoughtunless extinction in the intervening matter was very large. Thus, if confirmed,the reported amount of $^{44}$Ti in Cas A provides very interesting constraintson both the supernova environment and its mechanism. The abundances of$^{44}$Ti and $^{60}$Co ejected by Type II supernovae are such thatgamma-radiation from $^{44}$Ti decay SN 1987A could be detected by a futuregeneration of gamma-ray telescopes and that the decay of $^{60}$Co mightprovide an interesting contribution to the late time light curve of SN 1987Aand other Type II supernovae. To produce the solar $^{44}$Ca abundance andsatisfy all the observational constraints, nature may prefer at least theoccasional explosion of sub-Chandrasekhar mass white dwarfs as Type Iasupernovae. Depending on the escape fraction of positrons due to $^{56}$Co madein all kinds of Type Ia supernovae, a significant fraction of the steady statediffuse 511 keV emission may arise from the annihilation of positrons producedduring the decay of $^{44}$Ti to $^{44}$Ca. The Ca and Ti isotopic anomalies inpre-solar grains confirm the production of $^{44}$Ti in supernovae and thatComment: 27 pages including 7 figures. uuencoded, compressed, postscript. in  press Ap

The Production of 44Ti and 60Co in Supernovae