The Sun likely formed as part of a group of stars. A close stellar flyby by one of the solar siblings is probably responsible for the sharp outer edge in the solar system`s mass distribution. The frequency of such close flybys can be used to determine the likely type of birth environment of the solar system. Young stellar groups develop very quickly, expanding significantly within just a few Myr. Here we model this strong dynamical development of young stellar groups and determine the resulting close flyby history. We find that solar system equivalents are predominantly produced in areas with stellar densities in the range 5 $\times$ 10$^4$ pc$^{-3} $ 20 000 $M_{sun}$) and intermediate-mass mass, compact clusters ($M_c <$ 3000 $M_{sun}$). Current day counterparts would be the association NGC 2244 and the M44 cluster, respectively. In these two types of stellar groups, close flybys take place at a sufficiently high rate, while not being too destructive either. A final decision between these two remaining options will require incorporation of constraints from cosmo-chemical studies.

中文翻译：

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太阳的摇篮

太阳很可能是作为一组恒星的一部分而形成的。太阳系兄弟姐妹之一的近距离恒星飞越可能是太阳系质量分布中锐利外缘的原因。这种近距离飞越的频率可用于确定太阳系可能的出生环境类型。年轻的恒星群发展非常迅速，在短短几密尔内显着扩张。在这里，我们对年轻恒星群的这种强大动力发展进行建模，并确定由此产生的近距离飞越历史。我们发现太阳系等价物主要产生于恒星密度范围为 5 $\times$ 10$^4$ pc$^{-3} $ 20 000 $M_{sun}$) 和中等质量的区域，紧凑集群（$M_c <$ 3000 $M_{sun}$）。当前对应的星团将分别是 NGC 2244 星团和 M44 星团。在这两种类型的恒星群中，近距离飞越以足够高的速度发生，同时也没有太大的破坏性。这两个剩余选项之间的最终决定将需要结合宇宙化学研究的限制。