Telescopes versus Microscopes: the puzzle of Iron-60 - AstrophysicsReport as inadecuate

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Abstract: The discovery that the short-lived radionucleide iron-60 was present in theoldest meteorites suggests that the formation of the Earth closely followed thedeath of a massive star. I discuss three astrophysical origins: winds from anAGB star, injection of supernova ejecta into circumstellar disks, and inducedstar formation on the boundaries of HII regions. I show that the first two failto match the solar system iron-60 abundance in the vast majority of starforming systems. The cores and pillars on the edges of HII regions arespectacular but rare sites of star formation and larger clumps with masses1e3-1e4 solar masses at tens of parsec from a supernova are a more likely birthenvironment for our Sun. I also examine gamma-ray observations of iron-60 decayand show that the Galactic background could account for the low end of therange of meteoritic measurements if the massive star formation rate was atleast a factor of 2 higher 4.6 Gyr ago.

Author: Jonathan P. Williams



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