Recent observational studies of the chemical composition of circumstellar matter around both high- and low-mass young stellar objects are reviewed. The molecular abundances are found to be a strong function of evolutionary state, but not of system mass or luminosity. The data are discussed with reference to recent theoretical models.

中文翻译：

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年轻恒星周围星周物质的化学演化

回顾了最近对高质量和低质量年轻恒星物体周围星周物质化学成分的观测研究。发现分子丰度是进化状态的强函数，而不是系统质量或光度的函数。参考最近的理论模型讨论了这些数据。