KMS of Xinjiang Astronomical Observatory, CAS
| 天鹰座与W33巨分子云的氨分子观测研究 | |
| Alternative Title | Ammonia observations towards the Aquila Rift cloud complex and the W33 |
刊迪丽耶·图尔荪
| |
| Subtype | 博士 |
| Thesis Advisor | 加尔肯·叶生别克 |
| 2021-12-01 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Name | 理学博士 |
| Degree Discipline | 天体物理 |
| Keyword | 大质量恒星形成, 巨分子云, 运动学与动力学, 大质量原恒星和前恒星 |
| Abstract | 我们使用南山26m射电望远镜对天鹰座巨分子云的氨分子 (1,1) 和 (2,2)跃迁线进行研究，它包括 Serpens south 小质量恒星形成区与 W40 大质量恒星形成区。我们的观测覆盖范围为 ∼1.5∘ × 2.2∘ (11.4 pc × 16.7 pc). 从 NH3 (2,2)/(1,1) 中得到的天鹰座致密气体的运动学温度在 8.9∼35.0 K 之间，平均为 15.3 ± 6.1 K(误差是平均值的标准偏差)。小质量恒星形成区 Serpens south 的温度在 8.9∼16.8 K之间，平均为 12.3 ± 1.7 K，大质量恒星形成区 W40 的温度在 17.7∼35.0 K 之间，平均为 25.1 ± 4.9 K。大质量恒星形成区 W40 的运动学温度比小质量恒星形成区 Serpens south 的温度大 2 倍。从 NH3 (2,2)/(1,1) 中得出的气体运动学温度与 HiGal 尘埃温度进行对比得到天鹰座恒星形成区中 Serpens south 小质量恒星形成区的气体温度与尘埃温度是相等的，可大质量恒星形成区 W40 的气体温度比尘埃温度大。我们还发现沿整个天鹰座， Serpens South 和 W40 的速度梯度约为 0.16 ± 0.01 km s-1 pc-1， 0.27 ± 0.01 km s-1 pc-1，和 0.380 ± 0.001 km s-1 pc-1，它们可能来自天鹰座分子云的旋转。转动能与引力能之间的比率我们可以知道转动能是引力能中微不足道的一部分。 NH3(1,1) 速度弥散的湍流成分表现它与气体温度有关，这表明这个致密气体很有可能被湍流能量加热。通过与Herschel 红外连续谱的尘埃数据进行比较，我们计算出来的氨分子的总丰度𝜒 (total-NH3) = (total-𝑁 (NH3)) / 𝑁(H2) 范围 0.1 × 10-8 ∼ 2.1 × 10-7 之间，平均为 6.9 (±4.5) × 10-8。 Serpens south 的总丰度是 0.2 × 10-8 ∼ 2.1 × 10-7 之间，平均为 8.6 (±3.8) × 10-8。 W40 H II 区的丰度比 Serpens south 的丰度小，它的丰度范围 0.1 ∼ 4.3 × 10-8 之间，平均为 1.6 (±1.4) × 10-8。 W33巨分子云的距离相对较小，大约为2.4 kpc，是一个著名的大质量，高亮度， 10 pc 大小的恒星形成分子云复合体，其范围从静止的红外暗云到活跃的红外亮云，与年轻的大质量恒星，并与电离氢区相关。利用长坡段 18-26 GHz 之间的观测能探测到 NH3 (𝐽, 𝐾) = (1,1)，(2,2)， (3,3)， (4,4)， (5,5)， (6,6)， (2,1)， (3,2) 反演跃迁线。 W33 Main 中的 (3,3) 线还包括了氨脉泽。这个脉泽线近 36 年里没有表现出随时间的变化。我们测定了W33巨分子云中6个致密团块的NH3运动学温度、柱密度，丰度和其他物理性质。对这6个致密团块分别计算出来的 total-NH3 柱密度和 total-NH3 丰度表明 W33 Main 大质量恒星形成区 (H II 区) 的 total-NH3 柱密度和 total-NH3 丰度比W33巨分子云中其它5个致密团块低一个量级。由此可以确定这六个致密团块处于不同演化阶段并发现该区域没有接近W51-IRS2 或 Sgr B2 极端条件的热核。 Ortho-to-Para-NH3 的丰度比表明氨分子应该是在 ≳ 20 K 的运动学温度下在气相或尘埃上形成的。研究中只用 NH3 (1,1)和 (2,2) 线来确定气体运动学温度，并估算了W33巨分子云6个致密团块的体密度。使用这新的 𝑇kin 计算方法表明，得出来的体密度类似于那些由 Immer 等 (2014) 给出的体密度。从氨分子 𝑇kin 假设中还可以知道在这三个 W33 Main， W33 A， W33 B团块中温度梯度普遍存在。 |
| Other Abstract | We surveyed the Aquila Rift complex including the Serpens South and W 40 region in the NH3 (1,1) and (2,2) transitions making use of the Nanshan 26-m telescope. Our observations cover an area of ∼1.5∘ × 2.2∘ (11.4 pc × 16.7 pc). The kinetic temperatures of the dense gas in the Aquila Rift complex obtained from NH3 (2,2)/(1,1) ratios range from 8.9 to 35.0 K with an average of 15.3 ± 6.1 K (errors are standard deviations of the mean). Low gas temperatures associate with Serpens South ranging from 8.9 to 16.8 K with an average 12.3 ± 1.7 K, while dense gas in the W 40 region shows higher temperatures ranging from 17.7 to 35.0 K with an average of 25.1 ± 4.9 K. A comparison of kinetic temperatures derived from para-NH3 (2,2)/(1,1) against HiGal dust temperatures indicates that the gas and dust temperatures are in agrement in the low mass star formation region of Serpens South. In the high mass star formation region W 40, the measured gas kinetic temperatures are higher than those of the dust. The turbulent component of the velocity dispersion of NH3 (1,1) is found to be positively correlated with the gas kinetic temperature, which indicates that the dense gas may be heated by dissipation of turbulent energy. We also find velocity gradients of about 0.16 ± 0.01 km s-1 pc-1, 0.27 ± 0.01 km s-1 pc-1 and 0.380 ± 0.001 km s-1 pc-1 that run along the entire observed region, Serpens South and W 40 which likely arise from an overall rotation of the Aquila molecular cloud. It is demonstrated that the rotational energy is a negligible fraction of the gravitational energy. For the fractional total-NH3 (para+ortho) abundance obtained by a comparison with Herschel infrared continuum data representing dust emission we find that 𝜒 (total-NH3) = (total-𝑁 (NH3)) / 𝑁(H2) varies from 0.1 × 10-8 to 2.1 × 10-7 with an average of 6.9 (±4.5) × 10-8. Serpens South also shows a fractional total-NH3 (para+ortho) abundance ranging from 0.2 × 10-8 to 2.1 × 10-7 with an average of 8.6 (±3.8) × 10-8. In W 40, values are lower, between 0.1 and 4.3 × 10-8 with an average of 1.6 (±1.4) × 10-8. At adistance of 2.4 kpc, W33 is an outstanding massive and luminous 10 pc sized star formingcomplex containing quiescent infrared dark clouds as well as highly active infraredbright cloud cores heated by young massive stars. We report measurements of ammonia(NH3) inversion lines in the frequency range 18–26 GHz, obtained with the 40′′ resolution of the 100 m Effelsberg telescope. We have detected the (𝐽, 𝐾) = (1,1), (2,2), (3,3),(4,4), (5,5), (6,6), (2,1) and (3,2) transitions. There is a maser line in the (3,3) transition towards W33 Main. Brightness temperature and line shape indicate no significant variation during the last ∼36 yr. We have determined kinetic temperatures, column densities and other physical properties of NH3 and the molecular clouds in W33. For the total-NH3 column density and total-NH3 fractional abundance, we find that in the massive star forming region of W33 Main (H II region) are one order of magnitude lower than those of the other five W33 sources. From this, we confirm the already previously proposed different evolutionary stages of the six W33 clumps and find that there is no hot core in the region approaching the extreme conditions encountered in W51-IRS2 or Sgr B2. The ortho-to-para-NH3 abundance ratios suggest that ammonia should have been formed in the gas phase or on dust grain mantles at kinetic temperatures of ≳ 20 K. We determine kinetic temperatures only using NH3 (1,1) and (2,2), and from this we provide gas volume densities for the six main sources in the W33 region. Using our new 𝑇kin values shows that our volume densities are similar to those estimated by Immer at al. (2014), suggesting that ammonia beam filling factors are close to unity. |
| Pages | 139 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xao.ac.cn/handle/45760611-7/5156 |
| Collection | 研究生学位论文 |
| Affiliation | 中国科学院新疆天文台 |
| First Author Affilication | Xinjiang Astronomical Observatory, Chinese Academy of Sciences |
| Recommended Citation GB/T 7714 | 刊迪丽耶·图尔荪. 天鹰座与W33巨分子云的氨分子观测研究[D]. 北京. 中国科学院大学,2021. |
| Files in This Item: | ||||||
| File Name/Size | DocType | Version | Access | License | ||
| 天鹰座与W33巨分子云的氨分子观测研究_（13527KB） | 学位论文 | 暂不开放 | CC BY-NC-SA | Application Full Text | ||
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.
Edit Comment