Fedriani R, Caratti O Garatti A, Purser S J D, Sanna A, Tan J C, Garcia-Lopez R, Ray T P, Coffey D, Stecklum B, Hoare M
Dublin Institute for Advanced Studies, School of Cosmic Physics, Astronomy & Astrophysics Section, 31 Fitzwilliam Place, Dublin, D02 XF86, Ireland.
School of Physics, University College Dublin, Belfield, Dublin 4, Ireland.
Nat Commun. 2019 Aug 9;10(1):3630. doi: 10.1038/s41467-019-11595-x.
It is important to determine if massive stars form via disc accretion, like their low-mass counterparts. Theory and observation indicate that protostellar jets are a natural consequence of accretion discs and are likely to be crucial for removing angular momentum during the collapse. However, massive protostars are typically rarer, more distant and more dust enshrouded, making observational studies of their jets more challenging. A fundamental question is whether the degree of ionisation in jets is similar across the mass spectrum. Here we determine an ionisation fraction of ~5-12% in the jet from the massive protostar G35.20-0.74N, based on spatially coincident infrared and radio emission. This is similar to the values found in jets from lower-mass young stars, implying a unified mechanism of shock ionisation applies in jets across most of the protostellar mass spectrum, up to at least ~10 solar masses.
确定大质量恒星是否像低质量恒星那样通过盘吸积形成很重要。理论和观测表明，原恒星喷流是吸积盘的自然结果，并且在坍缩过程中对于去除角动量可能至关重要。然而，大质量原恒星通常更罕见、距离更远且被更多尘埃笼罩，这使得对其喷流的观测研究更具挑战性。一个基本问题是喷流中的电离程度在整个质量谱中是否相似。在此，我们基于空间上重合的红外和射电辐射，确定了来自大质量原恒星G35.20 - 0.74N的喷流中的电离分数约为5% - 12%。这与在低质量年轻恒星的喷流中发现的值相似，这意味着一种统一的激波电离机制适用于跨越大部分原恒星质量谱的喷流，至少达到约10个太阳质量。
