Ammonia in the hot core W51-IRS2: Maser line profiles, variability, and saturation
文献类型：期刊论文
| 作者 | Alkhuja, E.4,6; Henkel, C.3,6; Yan, Y.6; Winkel, B.6; Gong, Y.1,2,6; Wu, G.6; Wilson, T. L.6; Wootten, A.5; Malawi, A.4 |
| 刊名 | ASTRONOMY & ASTROPHYSICS
 |
| 出版日期 | 2025-08-19 |
| 卷号 | 700页码:A192 |
| 关键词 | ISM: clouds ISM: molecules ISM: individual objects: W51 |
| ISSN号 | 0004-6361 |
| DOI | 10.1051/0004-6361/202554839 |
| 产权排序 | 3 |
| 英文摘要 | W51-IRS2 is known to be one of the most prolific sources of interstellar ammonia (NH3) maser lines. So far, however, many of these inversion lines have rarely been studied. Here we report spectrally resolved line profiles for the majority of detected features and provide information on the variability of these maser components between 2012 and 2023. This includes the first tentative detection of a (J, K) = (5, 2) maser in the interstellar medium and the first tentative detection of a (6,4) maser in W51-IRS2. Furthermore, we report for the first time NH3 (9,6) maser emission below local standard of rest velocities of 50 km s(-1) in this source as well as double maser features occasionally seen in other transitions. The detected maser lines strongly indicate vibrational pumping by approximate to 10 mu m photons, which must be abundant due to the high kinetic temperature (approximate to 300 K) of the ammonia emitting gas. The detection of vibrationally excited NH3, suggesting a vibrational excitation temperature consistent with the kinetic one, and a comparison with measured SiO line profiles, are also presented. For the (10,7) line, we find a tentative correlation between flux density and line width compatible with unsaturated maser emission. The velocity drift of the so-called 45 km s(-1) maser features, reported to be +0.2 km s(-1) yr(-1) between 1996 and 2012, has either slowed down to values <0.1 km s(-1) or has entirely disappeared. In 2023, the component is only seen in ammonia inversion lines that are located at least 800 K above the ground state. The other features have faded. Possible scenarios explaining this phenomenon are discussed. |
| WOS关键词 | STAR-FORMING REGIONS ; GRAIN-SURFACE-CHEMISTRY ; MOLECULAR-SPECTROSCOPY ; COLOGNE DATABASE ; WATER MASER ; EMISSION ; INTERSTELLAR ; DISCOVERY ; W51 ; SIMULATIONS |
| 资助项目 | King Abdulaziz University and the Cultural Office of the Embassy of the Kingdom of Saudi Arabia in Berlin |
| WOS研究方向 | Astronomy & Astrophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001553558200008 |
| 出版者 | EDP SCIENCES S A |
| 资助机构 | King Abdulaziz University and the Cultural Office of the Embassy of the Kingdom of Saudi Arabia in Berlin |
| 源URL | [http://ir.xao.ac.cn/handle/45760611-7/8055]  |
| 专题 | 研究单元未命名 |
| 通讯作者 | Alkhuja, E. |
| 作者单位 | 1.Chinese Acad Sci, Key Lab Radioastron, 10 Yuanhua Rd, Nanjing 210023, Peoples R China 2.Chinese Acad Sci, Purple Mt Observ PMO, 10 Yuanhua Rd, Nanjing 210023, Peoples R China 3.Chinese Acad Sci, Xinjiang Astron Observ, Urumqi 830011, Peoples R China 4.King Abdulaziz Univ, Fac Sci, Astron Dept, POB 80203, Jeddah 21589, Saudi Arabia 5.Natl Radio Astron Observ, 520 Edgemont Rd, Charlottesville, VA 22903 USA 6.Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany |
| 推荐引用方式 GB/T 7714 | Alkhuja, E.,Henkel, C.,Yan, Y.,et al. Ammonia in the hot core W51-IRS2: Maser line profiles, variability, and saturation[J]. ASTRONOMY & ASTROPHYSICS,2025,700:A192. |
| APA | Alkhuja, E..,Henkel, C..,Yan, Y..,Winkel, B..,Gong, Y..,...&Malawi, A..(2025).Ammonia in the hot core W51-IRS2: Maser line profiles, variability, and saturation.ASTRONOMY & ASTROPHYSICS,700,A192. |
| MLA | Alkhuja, E.,et al."Ammonia in the hot core W51-IRS2: Maser line profiles, variability, and saturation".ASTRONOMY & ASTROPHYSICS 700(2025):A192. |
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来源：新疆天文台
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