We discovered new high-velocity components of H$_2$O maser emission in one of the "water fountain" sources, IRAS~18286$-$0959, which has been monitored using the Nobeyama 45 m telescope in the new FLASHING (Finest Legacy Acquisitions of SiO- and H$_2$O-maser Ignitions by Nobeyama Generation) project since 2018 December. The maser spectra show new, extremely high expansion velocities ($>$200~km~s$^{-1}$ projected in the line of sight) components, some of which are located symmetrically in the spectrum with respect to the systemic velocity. They were also mapped with KaVA (KVN and VERA Combined Array) in 2019 March. We located some of these maser components closer to the central stellar system than other high velocity components (50--200~km~s$^{-1}$) that have been confirmed to be associated with the known bipolar outflow. The new components would flash in the fast collimated jet at a speed over 300~km~s$^{-1}$ (soon) after 2011 when they had not been detected. The fastest of the new components seem to indicate rapid deceleration in these spectra, however our present monitoring is still too sparse to unambiguously confirm it (up to 50~km~s$^{-1}$yr$^{-1}$) and too short to reveal their terminal expansion velocity, which will be equal to the expansion velocity that has been observed ($v_{\rm exp}\sim$120~km~s$^{-1}$). Future occurrences of such extreme velocity components may provide a good opportunity to investigate possible recurrent outflow ignitions. Thus sculpture of the parental envelope will be traced by the dense gas that is entrained by the fast jet and exhibits spectacular distributions of the relatively stable maser features.

中文翻译：

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闪烁：IRAS 18286−0959 中的新型高速 H2O 脉泽

我们在其中一个“喷泉”源 IRAS~18286$-$0959 中发现了 H$_2$O 脉泽发射的新高速分量，已使用新 FLASHING（Finest Legacy Acquisitions）中的 Nobeyama 45 m 望远镜对其进行监测自 2018 年 12 月以来，Nobeyama Generation 的 SiO- 和 H$_2$O-maser Ignitions 项目。脉泽光谱显示出新的、极高的膨胀速度（$>$200~km~s$^{-1}$ 投影在视线中）分量，其中一些在光谱中相对于系统速度对称。它们还在 2019 年 3 月用 KaVA（KVN 和 VERA 组合阵列）进行了映射。我们发现其中一些脉泽分量比其他已确认与已知双极外流有关的高速分量 (50--200~km~s$^{-1}$) 更靠近中央恒星系统。在 2011 年之后，当它们未被发现时，新组件将以超过 300~km~s$^{-1}$（很快）的速度在快速准直射流中闪烁。最快的新组件似乎表明这些光谱中的快速减速，但是我们目前的监测仍然太稀疏而无法明确确认（高达 50~km~s$^{-1}$yr$^{-1}$ ) 并且太短而无法揭示它们的最终膨胀速度，这将等于已观察到的膨胀速度 ($v_{\rm exp}\sim$120~km~s$^{-1}$)。这种极端速度分量的未来出现可能提供一个很好的机会来研究可能的反复流出点火。因此，父母包层的雕刻将被快速射流夹带的致密气体追踪，并展示出相对稳定的脉泽特征的壮观分布。