AI 中文总结
研究大质量恒星形成区域G28.288$-$0.364的物理和运动学性质，通过分析多波长观测数据，包括射电连续谱、射电复合线、尘埃连续谱及分子线示踪剂等，揭示其演化阶段及尘埃核心情况，凸显高角分辨率观测对解析大质量恒星早期演化的重要性。
AI 中文摘要
大质量恒星在深度嵌入的尘埃核心中形成，超紧凑和超超紧凑H II区域的发展是其早期演化的特征。识别和分析这些区域对于理解控制大质量恒星形成的物理过程以及早期演化阶段之间的转变至关重要。本文研究了大质量恒星形成区域G28.288$-$0.364的物理和运动学性质，以限制嵌入H II区域及其周围核心的演化阶段。我们分析了多波长观测数据，包括uGMRT射电连续谱数据、GLOSTAR-D调查的存档连续谱和射电复合线数据、ALMAGAL调查的高角分辨率ALMA波段3射电复合线和1.36毫米尘埃连续谱数据以及互补的分子线示踪剂。我们得出了光谱指数，测量了射电复合线发射的线宽和速度，使用树状图分析识别了致密尘埃核心，并估计了它们的物理性质。射电连续谱发射呈现正光谱指数，与部分光学厚的自由-自由发射一致。高分辨率观测将电离气体解析为两个不同的成分，其物理尺寸约为0.06 pc，它们的RRL线宽（分别约为37和32 km s$^{-1}$）表明一个成分处于超紧凑和超超紧凑H II区域之间的过渡阶段，而另一个成分则更为演化。1.36毫米尘埃连续谱数据揭示了五个尘埃核心，其表面密度与大质量恒星形成的理论阈值一致。总之，这些结果突出了聚集环境中大质量恒星形成的复杂和相继性质，并证明了高角分辨率观测对于解析大质量恒星早期演化的重要性。
英文摘要
Massive stars form within deeply embedded dust cores, and the development of hypercompact and ultracompact H II regions characterizes their early evolution. Identifying and analyzing such regions is essential for understanding the physical processes that govern massive star formation and the transitions between early evolutionary stages. In this article, we investigate the physical and kinematic properties of the massive star-forming region G28.288$-$0.364 to constrain the evolutionary stages of embedded H II regions and the surrounding cores. We analyze multiwavelength observations, including uGMRT radio continuum data; archival continuum and radio recombination line data from the GLOSTAR-D survey; high-angular-resolution ALMA Band 3 radio recombination line and 1.36-mm dust continuum data from the ALMAGAL survey; and complementary molecular line tracers. We derive spectral indices, measure linewidths and velocities of the radio recombination line emission, identify compact dust cores using dendrogram analysis, and estimate their physical properties. The radio continuum emission exhibits a positive spectral index, consistent with partially optically thick free-free emission. High-resolution observations resolve the ionized gas into two distinct components with physical sizes of $\sim$ 0.06 pc, and their RRL linewidths ($\sim$ 37 and 32 km s$^{-1}$, respectively) indicate that one component is in a transitional stage between hypercompact and ultracompact H II regions, while the other is more evolved. The 1.36-mm dust continuum data reveal five dust cores with surface densities consistent with the theoretical threshold for massive star formation. In summary, these results highlight the complex and sequential nature of massive star formation in clustered environments and demonstrate the importance of high angular resolution observations for resolving the early evolution of massive stars.
Comments10 pages, 6 figures, Accepted for publication in Astronomy and Astrophysics
DOI：10.1051/0004-6361/202661242
