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F. C. Adams (Univ. Michigan), G. Laughlin (Lick Observatory )
Using the observed properties of our solar system -- the isotopic compositions of meteorites and the regularity of the planetary orbits -- we constrain the star formation environment of the Sun within the scenario of (external) radioactive enrichment by a massive star. This calculation yields a probability distribution for the number of stars in the solar birth aggregate. The Sun is most likely to have formed within a stellar group containing N=2000 members. The probability of a star forming in this type of environment is P = 0.0085, i.e., only about 1 out of 120 solar systems are expected to form under similar conditions. We discuss implications of this scenario, including possible effects from the radiation fields provided by the putative cluster environment and dynamical disruption of the Kuiper Belt. The constraints of this paper place tight restrictions on the properties of the solar birth aggregate for the scenario of external enrichment by a massive star; alternately, these tight constraints slightly favor a self-enrichment scenario for the short-lived radioactive species.
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Bulletin of the American Astronomical Society, 34, #3
© 2002. The American Astronomical Society.