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标题：The formation of solar-system analogs in young star clusters
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作者：S. Portegies Zwart
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：622
DOI：10.1051/0004-6361/201833974
语种：English
出版社：EDP Sciences
摘要：The solar system was once rich in the short-lived radionuclide (SLR)26Al but poor in60Fe. Several models have been proposed to explain these anomalous abundances in SLRs, but none has been set within a self-consistent framework of the evolution of the solar system and its birth environment. The anomalous abundance in26Al may have originated from the accreted material in the wind of a massive ≳20 M⊙Wolf-Rayet star, but the star could also have been a member of the parental star-cluster instead of an interloper or an older generation that enriched the proto-solar nebula. The protoplanetary disk at that time was already truncated around the Kuiper-cliff (at 45 au) by encounters with other cluster members before it was enriched by the wind of the nearby Wolf-Rayet star. The supernova explosion of a nearby star, possibly but not necessarily the exploding Wolf-Rayet star, heated the disk to ≳1500 K, melting small dust grains and causing the encapsulation and preservation of26Al in vitreous droplets. This supernova, and possibly several others, caused a further abrasion of the disk and led to its observed tilt of 5.6 ± 1.2° with respect to the equatorial plane of the Sun. The abundance of60Fe originates from a supernova shell, but its preservation results from a subsequent supernova. At least two supernovae are needed (one to deliver60Fe and one to preserve it in the disk) to explain the observed characteristics of the solar system. The most probable birth cluster therefore hasN = 2500 ± 300 stars and a radius ofrvir = 0.75 ± 0.25 pc. We conclude that systems equivalent to our solar system form in the Milky Way Galaxy at a rate of about 30 Myr−1, in which case approximately 36 000 solar-system analogs roam the Milky Way.
关键词：enmethods: numericalstars: formationplanetary systems