Astronomy and Astrophysics – Astrophysics
Scientific paper
Jul 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993metic..28q.337c&link_type=abstract
Meteoritics, vol. 28, no. 3, volume 28, page 337
Astronomy and Astrophysics
Astrophysics
Astrophysics, Extinct Nuclides, Iodine-Xenon, Isotopic Variation, Nucleosynthesis, Plutonium, Radioactivity, Radiogenic Ages, Xenon
Scientific paper
To understand the meaning of extinct radioactivity for the origin of the solar system, it is first necessary to compare the observed initial meteoritic concentrations of those nuclei to the concentrations that are expected in the mean interstellar medium. Any differences are attributed to special circumstances of solar birth. Traditionally one estimates the concentration ratio of extinct activity Z* to stable nuclide Z by Z*/Z = (y*/y)(tau/T(sub)G), where y* and y are the stellar yields of the two nuclei, tau is the mean lifetime of the extinct nucleus, and T(sub)G is the age of the Galaxy. However, by considering the history of growth of the mass of the Galactic disk by metal-poor infall, I have demonstrated by analytic solutions [1,2] that the mean radioactivity is enhanced relative to stable nuclei by the past infall. For the analytic family f(t)/M(sub)G (t) = k/(t+ delta) relating infall rate f(t) to gas mass MG(t) this increase is by a factor (k+1). The mean interstellar ratio becomes Z*/Z =(k+1 )(y*/y) (tau/T(sub)G). This enhancement impacts every known case. It becomes possible to account for the observed interstellar 26Al gamma emission by supernova nucleosynthesis if the infall parameter k=3-5. But by the same token the required free decay interval for ^129I is increased by about 40Myr. I will try to clarify this theoretical development. References: [1] Clayton D. D. (1985) in Challenges and new developments in nucleosynthesis, (W. D. Arnett and J. W. Truran, eds.), Univ. Chicago. [2] Clayton D. D. (1988) Monthly Notices R. Astron. Soc., 234, 1-36.
No associations
LandOfFree
Extinct Radioactivity and Evolution of the Galactic Disk does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Extinct Radioactivity and Evolution of the Galactic Disk, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Extinct Radioactivity and Evolution of the Galactic Disk will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1072483