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標題: | 論OMC1內絲狀結構之物理條件及氣體運動 Physical Conditions and Kinematics of the Filamentary Structure in Orion Molecular Cloud 1 |
作者: | Yu-Hsuan Teng 鄧郁璇 |
指導教授: | 朱有花(You-Hua Chu) |
關鍵字: | 星際介質,分子雲,恆星形成, ISM clouds,ISM structure,ISM kinematics and dynamics,ISM individual objects (OMC1),stars formation, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 本論文以N2H+ J=3-2譜線研究獵戶座分子雲1號(OMC1)中緻密氣體的結構與運動。我們分別用次毫米波陣列望遠鏡(SMA)和次毫米電波望遠鏡(SMT)觀測Orion KL 核心周圍6′ × 9′(約0.7 × 1.1 秒差距)的區域,並將二份觀測資料合併以補償陣列望遠鏡造成的光子損失(missing flux problem)。合併後的影像解析度約為5.4′′(約2300天文單位),其顯示OMC1 由眾多寬度約0.02–0.03 秒差距(pc) 的纖維(filament) 所組成,而其中三條纖維內含有不連續的緻密核心。我們利用N2H+ J=3-2及J=1-0二組譜線的數據進行非局部熱平衡分析(non-LTE analysis),從而推導出此區域的物理條件參數。分析結果顯示OMC1 東部的氣體溫度較高,而我們認為其能量來源是M42和M43星雲中高質量恆星的高能輻射。此外,纖維內部比起外部擁有更高的密度(∼10^7 cm−3)及更低的溫度(∼15–20 K);我們認為纖維內部的低溫正是由於內部的高密度氣體阻擋來自外部的恆星輻射。我們發現所有內部包含緻密核心的纖維都有大約80 M⊙ pc−1 以上的單位長度質量(line density),且這些核心的質量約在0.1–3 倍太陽質量之間。其中一條纖維的強度變化與速度變化更呈現出明顯的相位差,根據當前理論,這代表該纖維中的氣體正在形成核心,也暗示著此纖維相較於另一條已有恆星形成跡象的纖維而言,仍處於較早期的演化階段。 We have studied the structure and kinematics of the dense molecular gas in the Orion Molecular Cloud 1 (OMC1) region with the N2H+ 3-2 line. The 6′ × 9′ (∼ 0.7 × 1.1 pc) region surrounding the Orion KL core has been mapped with the Submillimeter Array (SMA) and the Submillimeter Telescope (SMT). The combined SMA and SMT image having a resolution of ∼ 5.4′′ (∼ 2300 au) reveals multiple filaments with a typical width of 0.02–0.03 pc, three of which contain high-intensity, clumpy cores. Physical conditions of the dense gas in OMC1 have been studied with the non-LTE analysis using the N2H+ 3-2 and 1-0 data. We find that the gas kinetic temperature in the eastern part of OMC1 is significantly higher than the remaining area, likely due to the external heating from the high mass stars in M42 and M43. We also find that the filaments have a higher density, ∼ 10^7 cm−3, and a lower temperature, ∼ 15–20 K, than the non-filament regions. The lower temperatures in the filaments could be explained by the shielding from the external heating due to the dense gas in the filaments. All filaments with core fragmentation have line densities > 80 M⊙ pc−1, and the core masses inside the filaments are typically 0.1–3 M⊙. One of the filaments with core fragmentation shows a clear phase shift between the sinusoidal patterns of the intensity and velocity variations, which implies that core formation is still ongoing in this region. Hence, this filament is likely to be in an earlier evolutionary phase than another filament with star formation signature. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/72701 |
DOI: | 10.6342/NTU201901320 |
全文授權: | 有償授權 |
顯示於系所單位: | 物理學系 |
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