AI 中文总结
研究发现原恒星系统HOPS 198的外流张角差异由两侧核密度不同导致，证实外流张角演化受原恒星核密度驱动。
AI 中文摘要
原恒星外流被认为是导致原恒星核恒星形成效率低下的原因。然而，外流能否驱散核中相当一部分气体取决于外流的张角。目前已确定，在原恒星演化的早期阶段，外流张角会增大，但潜在机制尚不清楚。对猎户座A分子云中0级原恒星HOPS 198的观测为该问题提供了线索。HOPS 198的外流及其核呈现出强烈的东西不对称性：东瓣的张角约为80°，是西瓣约30°的两倍多，而核西侧的面密度是东侧的1.5至2.8倍。通过分析模型（其中分子外流的形态由广角原恒星风（≥80°）与核周围物质的相互作用塑造），研究人员发现，两个瓣的张角差异可由核两侧的密度差异解释。该结果支持外流张角的演化由原恒星核密度演化驱动的假设。
英文摘要
Protostellar outflows are thought to be responsible for the low star formation efficiency of protostellar cores. However, whether outflows can disperse a significant fraction of the gas in the core depends on the outflow opening angle. It is established that the outflow opening angle increases during the early stages of the protostellar evolution, but the underlying mechanism is poorly understood. Observations of HOPS 198, a Class 0 protostar in the Orion A molecular cloud, provide insights into this question. HOPS 198 exhibits a strong east-west asymmetry in its outflow and its core. The opening angle of the eastern lobe ($\sim80^{\circ}$) is more than twice wider than that of the western lobe ($\sim30^{\circ}$), while the surface density of the west side of the core is $1.5-2.8$ times higher than the east side. Using an analytical model in which the molecular outflow morphology is shaped by interactions between the wide-angle protostellar wind ($\gtrsim 80^{\circ}$) and surrounding material in the core, we find that the difference in opening angle for the two lobes can be explained by the difference in core density on the two sides. This result supports the hypothesis that the evolution of the outflow opening angle is driven by the evolution in the density of the protostellar core.
CommentsAccepted for publication in Astronomy & Astrophysics
DOI：10.1051/0004-6361/202659651
