Understanding the relative importance of magnetic field, gravity, and turbulence in star formation at the hub of the giant molecular cloud G148.24+00.41

IF 4.7 3区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Monthly Notices of the Royal Astronomical Society Pub Date : 2024-01-09 DOI:10.1093/mnras/stae053

Vineet Rawat, M R Samal, Chakali Eswaraiah, Jia-Wei Wang, Davide Elia, Sandhyarani Panigrahy, A Zavagno, R K Yadav, D L Walker, J Jose, D K Ojha, C P Zhang, S Dutta

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Abstract

The relative importance of magnetic fields, turbulence, and gravity in the early phases of star formation is still not well understood. We report the first high-resolution dust polarization observations at 850 μm around the most massive clump, located at the hub of the Giant Molecular Cloud G148.24+00.41, using SCUBA-2/POL-2 at the James Clerk Maxwell Telescope. We find that the degree of polarization decreases steadily towards the denser portion of the cloud. Comparing the intensity gradients and local gravity with the magnetic field orientations, we find that local gravity plays a dominant role in driving the gas collapse as the magnetic field orientations and gravity vectors seem to point towards the dense clumps. We also find evidence of U-shaped magnetic field morphology towards a small-scale elongated structure associated with the central clump, hinting at converging accretion flows towards the clump. Our observation has resolved the massive clump into multiple substructures. We study the magnetic field properties of two regions, central clump (CC) and northeastern elongated structure (NES). Using the modified Davis-Chandrasekhar-Fermi method, we determine that the magnetic field strengths of CC and NES are ∼24.0 ± 6.0 μG and 20.0 ± 5.0 μG, respectively. The mass-to-flux ratios are found to be magnetically transcritical/supercritical, while the Alfv$\acute{\text{e}}$n Mach number indicates a trans-Alfv$\acute{\text{e}}$nic state in both regions. These results, along with Virial analysis, suggest that at the hub of G148.24+00.41, gravitational energy has an edge over magnetic and kinetic energies.

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了解磁场、重力和湍流在巨型分子云 G148.24+00.41 中心恒星形成过程中的相对重要性

磁场、湍流和引力在恒星形成早期阶段的相对重要性还没有得到很好的理解。我们利用詹姆斯-克拉克-麦克斯韦望远镜（James Clerk Maxwell Telescope）的SCUBA-2/POL-2，首次在位于巨分子云G148.24+00.41中心的最大质量团块周围进行了850微米的高分辨率尘埃极化观测。我们发现，偏振程度在向云的高密度部分逐渐减弱。将强度梯度和当地引力与磁场方向进行比较，我们发现当地引力在驱动气体塌缩方面起着主导作用，因为磁场方向和引力矢量似乎都指向高密度团块。我们还发现了与中心团块相关的小尺度拉长结构的 U 形磁场形态证据，暗示着向团块汇聚的吸积流。我们的观测将大质量星团解析为多个子结构。我们研究了中央团块（CC）和东北拉长结构（NES）这两个区域的磁场特性。利用改进的 Davis-Chandrasekhar-Fermi 方法，我们确定 CC 和 NES 的磁场强度分别为 ∼24.0 ± 6.0 μG 和 20.0 ± 5.0 μG。质量流量比被认为是跨临界/超临界磁场，而 Alfv$acute\{text{e}$n 马赫数则表明这两个区域都处于跨 Alfv$acute\{text{e}$nic 状态。这些结果以及室温分析表明，在G148.24+00.41的枢纽处，引力能比磁能和动能更有优势。

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来源期刊

Monthly Notices of the Royal Astronomical Society ASTRONOMY & ASTROPHYSICS-

CiteScore

9.10

自引率

37.50%

发文量

3198

审稿时长

3 months

期刊介绍： Monthly Notices of the Royal Astronomical Society is one of the world''s leading primary research journals in astronomy and astrophysics, as well as one of the longest established. It publishes the results of original research in positional and dynamical astronomy, astrophysics, radio astronomy, cosmology, space research and the design of astronomical instruments.