{sup 26}Al and {sup 60}Fe from supernova explosions
- University of Chicago, LASR, Chicago, Illinois 60637 (United States)
- University of California-Santa Cruz, Astronomy Department, Santa Cruz, California 95064 (United States)
- Clemson University, Department of Physics and Astronomy, Clemson, South Carolina 29634 (United States)
- Lawrence Livermore National Laboratory, General Studies Division, Livermore, California 94550 (United States)
- European Southern Observatory, K. Schwartzschild Strasse 2, D-8046, Garching (Germany)
Using recently calculated yields for Type II supernovae, along with models for chemical evolution and the distribution of mass in the interstellar medium, the current abundances and spatial distributions of two key gamma-ray radioactivities, {sup 26}Al and {sup 60}Fe, are determined. The estimated steady state production rates are 2.0{plus_minus}1.0 {ital M}{sub {circle_dot}} Myr{sup -1} for {sup 26}Al and 0.75{plus_minus}0.4 {ital M}{sub {circle_dot}} Myr{sup -1} for {sup 60}Fe. This corresponds to 2.2{plus_minus}1.1 {ital M}{sub {circle_dot}} of {sup 26}Al and 1.7{plus_minus}0.9 {ital M}{sub {circle_dot}} of {sup 60}Fe in the present interstellar medium. Sources of uncertainty are discussed, one of the more important being the current rate of core collapse supernovae in the Galaxy. Our simple model gives three per century, but reasonable changes in the star formation rate could easily accommodate a core collapse rate one-half as large, and thus one-half the yields. When these stellar and chemical evolution results are mapped into a three-dimensional model of the Galaxy, the calculated 1809 keV gamma-ray flux map is consistent with the {ital Compton} {ital Gamma} {ital Ray} {ital Observatory} observations of a steep decline in the flux outside a longitude of {plus_minus}50{degree} from the Galactic center, and the slight flux enhancements observed in the vicinity of spiral arms. Other potential stellar sources of {sup 26}Al and {sup 60}Fe are mentioned, especially the possibility of {sup 60}Fe synthesis in Type Ia supernovae. Predictions for the {sup 60}Fe mass distribution, total mass, and flux map are given. {copyright} {ital 1995 The American Astronomical Society.}
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 254128
- Journal Information:
- Astrophysical Journal, Vol. 449, Issue 1; Other Information: PBD: Aug 1995
- Country of Publication:
- United States
- Language:
- English
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