MIAO-ALMA：L/M < 1 L⊙/M⊙ 的70 μm暗团块中的激波与原恒星外流
MIAO-ALMA: Shocks and Protostellar Outflows in 70 $μ$m-dark clumps with $L/M$ $<$ 1 $L_{\odot}$/$M_{\odot}$
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中文总结 AI 辅助
本研究以MIAO项目为基础，用ALMA观测16个L/M<1 L⊙/M⊙的70 μm暗团块，识别37个外流，发现外流参数与驱动核质量正相关，还探测到未关联已知原恒星的激波，证明年轻环境中已存在原恒星活动。
中文摘要 AI 辅助
为研究大质量恒星形成区的初始条件，作为70 μm暗亮云多波长线成像巡天（MIAO）项目的一部分，我们利用SiO (2-1)发射线，对16个光度质量比（L/M）< 1 L⊙/M⊙的70 μm暗大质量团块，开展早期激波相关运动学的研究。借助阿塔卡马大型毫米波/亚毫米波阵列（ALMA）的观测，空间分辨率约为0.06 pc，速度分辨率为0.21 km s⁻¹，我们共识别出37个具有多种形态的外流。外流参数通过积分HCO⁺ (1-0)线翼推导得出，排除了由H¹³CO⁺ (1-0)示踪的宁静致密核成分。我们发现外流质量和速度与其驱动核的质量呈中等正相关。由于观测的高灵敏度，相较于此前研究，我们获得了更长的投影外流长度，由此推导的外流动力学年龄跨度约为10³-10⁵年。我们探测到6条窄线宽（0.6-1.4 km s⁻¹）和3条宽线宽（> 2 km s⁻¹）的SiO (2-1)特征，这些特征与已明确识别的原恒星驱动的外流无关。由于缺乏对应的3 mm尘埃连续谱核，它们的起源可能是未被探测到的低质量原恒星产生的年轻外流、耗散激波、云-云碰撞，或外流靠近天球平面时的投影效应。在如此极端年轻的环境中探测到这些激波和外流，表明原恒星活动已经开始。
英文摘要
To investigate the initial conditions of high-mass star-forming regions, we use SiO (2-1) emission to trace early shock-related kinematics toward sixteen 70 $μ$m-dark and massive clumps with luminosity-to-mass ratios ($L/M$) $< 1\,L_{\odot}/M_{\odot}$, as part of the Multiwavelength Line-Imaging Survey of the 70 $μ$m-dark and bright clouds (MIAO) project. Using ALMA observations at a spatial resolution of $\sim$0.06 pc and a velocity resolution of 0.21 km s$^{-1}$, we identify a total of thirty-seven outflows with a variety of morphologies. Outflow parameters were derived by integrating the HCO$^+$ (1-0) line wings, excluding the quiescent dense core component traced by H$^{13}$CO$^+$ (1-0). We find that outflow masses and velocities show moderate positive correlations with the masses of their driving cores. Owing to the high sensitivity of our observations, which yield longer projected outflow lengths compared to previous studies, the derived outflow dynamical ages span $\sim10^{3}$-$10^{5}$ yr. We detect six narrow-linewidth (0.6-1.4 km s$^{-1}$) and three broad ($>$ 2 km s$^{-1}$) SiO (2-1) features not associated with outflows driven by clearly identified protostars. Lacking coincident 3 mm dust continuum cores, their origins may be young outflows from undetected low-mass protostars, dissipating shocks, cloud-cloud collisions, or projection effects when the outflows lie close to the plane of the sky. The detection of these shocks and outflows in such extremely young environments demonstrates that protostellar activity has already begun.
