Numerical simulations have predicted that substructures such as spiral arms can be produced through a gravitationally unstable disk around high-mass young stellar objects (HMYSOs)^1,2,3,4,5. Recent high-resolution observations from the Atacama Large Millimeter/submillimeter Array have investigated these substructures at a spatial resolution of ~100 au (refs. ^6,7,8,9,10). An accretion burst, which is a manifestation of an increase in the accretion rate caused by a gravitational instability in the disk^1,11,12, can result in luminosity outbursting phenomena—as has been seen in several HMYSOs^13,14. However, no clear relationship between the accretion bursts and disk substructures has been established. Here we report the detections of three new molecular maser species, HDO, HNCO and ¹³CH₃OH, from the direction of the HMYSO G358.93-0.03 during a 6.7 GHz methanol maser flaring event¹⁵. High-quality imaging of the three new maser species exhibits consistent observational evidence that these masers closely trace the spiral-arm substructures around this HMYSO. The rapid decay of the spectral lines emitted from these molecules suggests that these are transient phenomena (for only ~1 month), probably associated with rapid changes in radiation field due to an accretion burst. Therefore, these new maser species provide evidence linking the spiral-arm substructure with an accretion burst, both expected from massive disk instabilities.

数值模拟预测，可以通过围绕高质量年轻恒星物体（HMYSOs）^1,2,3,4,5的重力不稳定盘来产生诸如螺旋臂之类的子结构。来自阿塔卡马大毫米波/亚毫米波阵列的最新高分辨率观测已经以〜100 au的空间分辨率研究了这些亚结构（参考文献^6,7,8,9,10）。吸积爆发（这是由磁盘^1,11,12中的重力不稳定性引起的吸积速率增加的体现）可以导致发光度突出现象（如在多个HMYSO ^13,14中所见）。但是，在吸积爆发和磁盘子结构之间尚未建立明确的关系。在这里，我们报告了在6.7 GHz甲醇maser燃烧事件期间从HMYSO G358.93-0.03的方向检测到的三种新分子maser物质，HDO，HNCO和¹³ CH ₃ OH ¹⁵。三种新型maser物种的高质量成像显示出一致的观察证据，表明这些maser紧密追踪了HMYSO周围的螺旋臂亚结构。从这些分子发出的光谱线的快速衰减表明，这是瞬时现象（仅持续约1个月），可能与由于增生爆发引起的辐射场快速变化有关。因此，这些新的maser物种提供了将螺旋臂子结构与吸积爆发联系起来的证据，这两者都是由于巨大的磁盘不稳定而引起的。