Title: ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -XIII. Ongoing triggered star formation within clump-fed scenario found in the massive ($\sim1500$ $\rm M_\odot$) clump Show Chinese title

Title: 分子云：ALMA三毫米波段对大质量恒星形成区的观测——第十三部分。 在大质量（$\sim1500$ $\rm M_\odot$）团块中发现的由团块供料触发的恒星形成仍在继续。

Abstract: Whether ionization feedback triggers the formation of massive stars is highly debated. Using ALMA 3 mm observations with a spatial resolution of $\sim 0.05$ pc and a mass sensitivity of 1.1 $\rm M_\odot$ beam$^{-1}$ at 20 K, we investigate the star formation and gas flow structures within the ionizing feedback-driven structure, a clump-scale massive ($\gtrsim 1500$ $\rm M_\odot$) bright-rimmed cloud (BRC) associated with IRAS 18290-0924. This BRC is bound only if external compression from ionized gas is considered. A small-scale ($\lesssim1$ pc) age sequence along the direction of ionizing radiation is revealed for the embedded cores and protostars, which suggests triggered star formation via radiation-driven implosion (RDI). Furthermore, filamentary gas structures converge towards the cores located in the BRC's center, indicating that these filaments are fueling mass towards cores. The local core-scale mass infall rate derived from H$^{13}$CO$^+$ $J=1-0$ blue profile is of the same order of magnitude as the filamentary mass inflow rate, approximately 1 $\rm M_\odot$ kyr$^{-1}$. A photodissociation region (PDR) covering the irradiated clump surface is detected in several molecules, such as CCH, HCO$^+$, and CS whereas the spatial distribution stratification of these molecules is indistinct. CCH spectra of the PDR possibly indicate a photoevaporation flow leaving the clump surface with a projected velocity of $\sim2$ km s$^{-1}$. Our new observations show that RDI accompanied by a clump-fed process is operating in this massive BRC. Whether this combined process works in other massive BRCs is worth exploring with dedicated surveys. Show Chinese abstract

Abstract: 电离反馈是否触发大质量恒星的形成仍存在很大争议。利用 ALMA 3 毫米观测数据（空间分辨率为$\sim 0.05$pc，灵敏度为 1.1 $\rm M_\odot$ 20 K 时的$^{-1}$光束），我们研究了由电离反馈驱动结构内的恒星形成和气体流动结构，该结构是一个与 IRAS 18290-0924 相关的团块尺度的大质量 ($\gtrsim 1500$ $\rm M_\odot$ ) 明亮边缘云 (BRC)。如果考虑来自电离气体的外部压缩，这个 BRC 才是受束缚的。沿电离辐射方向揭示了一个小规模的 ($\lesssim1$pc) 年龄序列，嵌入的核心和原恒星位于其中，这表明通过辐射驱动塌缩 (RDI) 触发了恒星形成。此外，发现丝状气体结构向位于 BRC 中心的核心汇聚，表明这些丝状体正在向核心输送质量。 The local core-scale mass infall rate derived from H$^{13}$CO$^+$ $J=1-0$ blue profile is of the same order of magnitude as the filamentary mass inflow rate, approximately 1 $\rm M_\odot$ kyr$^{-1}$. A photodissociation region (PDR) covering the irradiated clump surface is detected in several molecules, such as CCH, HCO$^+$, and CS whereas the spatial distribution stratification of these molecules is indistinct. PDR的CCH谱线可能表明有光致蒸发流从云团表面流出，投影速度为$\sim2$ 公里每秒$^{-1}$。 我们的新观测结果显示，在这个大质量BRC中，伴随着云团供料过程的RDI正在发生。 这种组合过程是否在其他大质量BRC中起作用，值得通过专门的巡天进行探索。