On the Number of Stars in the Sun's Birth Cluster

TL;DR

This paper investigates the likely size of the Sun's original star cluster by analyzing the probability of a supernova occurring during its formation, which influences the presence of certain isotopes in early solar system materials.

Contribution

It revisits the estimated number of stars in the Sun's birth cluster considering the probability of a supernova event during star formation.

Findings

Number of stars can be larger than previously estimated

Probability of supernova influences cluster size estimate

Star formation duration affects cluster size estimate

Abstract

The Sun is thought to be formed within a star cluster. The coexistence of $^{26}{\rm Al}$-rich and $^{26}{\rm Al}$-poor calcium--aluminum-rich inclusions indicates that a direct injection of $^{26}{\rm Al}$-rich materials from a nearby core-collapse supernova should occur in the first $10^5$ years of the solar system. Therefore, at least one core-collapse supernova should occur within the duration of star formation in the Sun's birth cluster. Here we revisit the number of stars in the Sun's birth cluster from the point of view of the probability for acquiring at least one core-collapse supernova within the finite duration of star formation in the birth cluster. We find that the number of stars in the birth cluster can be significantly larger than that previously considered, depending on the duration of star formation.