ASHES样本（GLASHES）中的全局与局域吸积。III. 70 $μ$m暗大质量团块中向致密核收缩运动的物理参数
Global and Local Infall in the ASHES Sample (GLASHES). III. Physical Parameters of Contracting Motion onto Dense Cores in 70 $μ$m Dark Massive Clumps
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中文总结 AI 辅助
本研究针对ASHES样本（GLASHES）中70 μm暗大质量团块内的致密核，利用Hill5模型拟合蓝不对称线轮廓，获取了内落速度和质量内吸积率，发现其随核演化阶段系统增加，且与低质量恒星形成区核相比更大，为大质量恒星形成早期的核尺度质量积累提供了统计约束。
中文摘要 AI 辅助
核增长是大质量恒星形成的关键过程。作为GLASHES（ASHES样本中的全局与局域吸积）巡天的一部分，我们针对嵌入70 μm暗大质量团块中的核，通过蓝不对称线轮廓推导了内落速度和质量内吸积率。在135个呈现蓝不对称轮廓的核中，70个获得了可靠的Hill5模型拟合，得到的内落速度为0.11--1.60 km s$^{-1}$，质量内吸积率范围为$\sim$10$^{-5}$至$5\times10^{-3}\,M_\odot\,{\rm yr}^{-1}$。这两个量从前恒星候选体到暖核再到外流关联核均呈系统性增加。推导的内落速度接近核的自由下落速度（均值$v_{\rm in}/v_{\rm ff}\sim0.75$），$t_{\rm in}=R/v_{\rm in}$与自由下落时间相当，表明是动力学快速收缩。Hill5内落速度与从光学薄示踪物测得的非热速度弥散和马赫数呈中等相关，说明有序内落对观测到的线宽有贡献。质量内吸积率与核质量呈幂律关系$\dot{M}=1.3\times10^{-4}\,(M/M_\odot)^{0.83\pm 0.06}\,M_\odot\,{\rm yr}^{-1}$，跨越$0.1\,M_\odot \lesssim M \lesssim 30\,M_\odot$。幂律指数从前恒星核的$\sim$0.65增加到外流关联核的$\sim$1.10，可能反映了主导物理过程的演化。GLASHES核的Hill5内落速度和质量内吸积率大于附近低质量恒星形成区核的对应值，但小于更大尺度大质量团块的对应值。这些结果为大质量恒星形成最早阶段的核尺度质量积累提供了首批统计约束。
英文摘要
Core growth is a key process in high-mass star formation. As part of the GLASHES (Global and Local Infall in the ASHES Sample) survey, we present infall velocities and mass infall rates derived from blue-asymmetric line profiles toward cores embedded in massive 70 \textmu m-dark clumps. Robust Hill5 model fits were obtained for 70 of the 135 cores exhibiting blue-asymmetric profiles, yielding infall velocities of 0.11--1.60 km s$^{-1}$ and mass infall rates ranging from $\sim$10$^{-5}$ to $5\times10^{-3}\,M_\odot\,{\rm yr}^{-1}$. Both quantities increase systematically from prestellar candidates to warm cores and outflow-associated cores. The inferred infall velocities are close to the cores' free-fall velocities (mean $v_{\rm in}/v_{\rm ff}\sim0.75$) and $t_{\rm in}=R/v_{\rm in}$ is comparable to the free-fall time, indicating dynamical fast contraction. Hill5 infall velocity correlates moderately with the non-thermal velocity dispersion and Mach number measured from optically thin tracers, indicating that organized infall contributes to the observed line widths. The mass infall rate follows a power-law relation with core mass, $\dot{M}=1.3\times10^{-4}\,(M/M_\odot)^{0.83\pm 0.06}\,M_\odot\,{\rm yr}^{-1}$, across $0.1\,M_\odot \lesssim M \lesssim 30\,M_\odot$. The power-law index increases from $\sim$0.65 for prestellar cores to $\sim$1.10 for outflow-associated cores, likely tracing an evolution in the dominant physical process. The Hill5 infall velocities and mass infall rates for the GLASHES cores are larger than those of cores in nearby low-mass star forming regions but smaller than those of larger scale high-mass clumps. These results provide the first statistical constraints on core-scale mass accumulation during the earliest stages of high-mass star formation.
发表机构
- Department of Astronomy, School of Science, The University of Tokyo（东京大学理学部天文学系）
- Green Bank Observatory（格林班克天文台）
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