Hydrogen recombination lines are one of the major diagnostics of H II region physical properties and kinematics. In the near future, the Expanded Very Large Array (EVLA) and the Atacama Large Millimeter Array (ALMA) will allow observers to study recombination lines in the radio and sub-mm regime in unprecedented detail. In this paper, we study the properties of recombination lines, in particular at ALMA wavelengths. We find that such lines will lie in almost every wideband ALMA setup and that the line emission will be equally detectable in all bands. Furthermore, we present our implementation of hydrogen recombination lines in the adaptive-mesh radiative transfer code RADMC-3D. We particularly emphasize the importance of non-LTE (local thermodynamical equilibrium) modeling since non-LTE effects can drastically affect the line shapes and produce asymmetric line profiles from radially symmetric H II regions. We demonstrate how these non-LTE effects can be used as a probe of systematic motions (infall & outflow) in the gas. We use RADMC-3D to produce synthetic observations of model H II regions and study the necessary conditions for observing such asymmetric line profiles with ALMA and EVLA.
Unveiling the First O-Type Bloated Star Candidate through ALMA and EVLA Observations
Instituto de Radioastronomía y Astrofísica, UNAM（墨西哥国立自治大学无线电天文学与天体物理研究所）；Institut de Ciències de l’Espai (ICE–CSIC)（太空科学研究所（加泰罗尼亚高等科研理事会））；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚空间研究学院）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Faculty of Physics, University of Duisburg–Essen（杜伊斯堡-埃森大学物理学院）；Centro de Astrobiología (CAB), CSIC–INTA（国家航空航天技术研究所与加泰罗尼亚高等科研理事会联合天体生物学中心）；Aryabhatta Research Institute of Observational Sciences (ARIES)（阿耶波多观测科学研究所以）
Unveiling Extragalactic Star Formation Using Radio Recombination Lines: An EVLA Pilot Study with NGC 253
射电复合线（RRL）是年轻恒星形成区电离气体的强大、无干扰的诊断。不幸的是，这些线在外部星系中很难检测到。本文介绍了一个近核星暴星系NGC253在33GHz处的RRL和射电连续辐射的EVLA观测结果。我们检测到以前未观察到的H58a和H59a RRL，并同时进行灵敏的连续测量。我们分别测量了H58 a和H59 a系的$44.3 \pm 0.7$ W m $^{-2}$和$39.9 \pm 0.8$ W m $^{-2}$的积分线通量。NGC 253中的热气体是运动学上复杂的，具有多个速度分量。我们将热气体的密度限制为$1.4 - 4 \times 10^4$ cm $^{-3}$，并估计了$1 \times 10^{53}$ s $^{-1}$的电离光子通量。我们使用RRL运动学和导出的电离光子通量表明，NGC 253的核区域是不受引力约束的，这与从X射线和H α测量推断的气体流出是一致的。H58a和H59a谱线的谱线轮廓、通量和运动学与不同频率的RRL一致，证实了以前更困难的高频观测的准确性。我们发现EVLA对于河外RRL观测的效率比VLA高一个数量级。这些观测结果证明了EVLA的能力和未来利用EVLA进行河外RRL研究的潜力。
Star formation traced by optical and millimeter hydrogen recombination lines and free-free emissions in the dusty merging galaxy NGC 3256 -- MUSE/VLT and ALMA synergy
ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- IV. Radio Recombination Lines and evolution of star formation efficiencies
University of Hertfordshire（赫特福德大学）；University of Manchester（曼彻斯特大学）；University of Leeds（利兹大学）；National Astronomical Observatory of Japan（日本国立天文台）；SOKENDAI (The Graduate University for Advanced Studies)（综合研究大学院大学）；University of Lincoln（林肯大学）；Liverpool John Moores University（利物浦约翰摩尔斯大学）
Electron temperature and emission measure of HII regions in the central molecular zone (CMZ) from H40 αrecombination line and continuum emissions by ALMA CMZ Exploration Survey - ACES -
Institute of Astronomy, The University of Tokyo（东京大学天文学研究所）；Astrophysics Research Institute, Liverpool John Moores University（利物浦约翰摩尔斯大学天体物理研究所）；CCosmic Origins Of Life (COOL)（宇宙生命起源中心（COOL））；UK ALMA Regional Centre Node, Jodrell Bank Centre for Astrophysics, Oxford Road, The University of Manchester（曼彻斯特大学约德尔银行天体物理学中心英国ALMA区域中心节点）；Department of Astronomy, University of Florida（佛罗里达大学天文学系）；Max Planck Institute for Astronomy（马克斯·普朗克天体物理学研究所）；Center for Astrophysics and Space Astronomy（科罗拉多大学博尔德分校天体物理学与空间天文中心；天体物理与行星科学系）；Department of Astrophysical and Planetary Sciences；University of Colorado, Boulder
Discovery of thermal radio recombination line emission toward the high-mass protostar IRAS18162$-$2048
Instituto de Astrofísica de Andalucía, CSIC（安达卢西亚天体物理研究所）；National Astronomical Observatory of Japan（日本国立天文台）；Osservatorio Astrofisico di Arcetri（阿切特里天文台）；Universitat de Barcelona (IEEC-UB)（巴塞罗那大学）；Institut de Radioastronomie Millimétrique（毫米波射电天文研究所）
ALMA-QUARKS: Few-Thousand-Year Hatching out of "Egg": The Supersonic Breakout of a Hypercompact H II Region from Its Parental Hot Core
Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS（中国科学院南美天文中心，国家天文台）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学天体物理研究所）；Max Planck Institute for Astronomy（马克斯·普朗克天文学研究所）；Department of Astronomy, The University of Texas at Austin（德克萨斯大学奥斯汀分校天文系）；Aix Marseille Univ, CNRS, CNES, LAM（艾克斯-马赛大学，法国国家科学研究中心，法国国家空间研究中心，拉格朗日天体物理实验室）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；School of Physics and Astronomy, Yunnan University（云南大学物理与天文学院）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences（中国科学院射电天文与技术重点实验室）；Indian Institute of Space Science and Technology（印度空间科学与技术学院）；Korea Astronomy and Space Science Institute（韩国天文与空间科学研究院）；University of Science and Technology, Korea (UST)（韩国科学技术院）；School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）
Resolving dense photodissociation regions: the structure of photochemical fronts in three-dimensional gas distributions
Faculty of Physics, University of Duisburg-Essen（杜伊斯堡-埃森大学物理学院）；Research Center for Computational Earth and Space Science, Zhejiang Lab（浙江实验室计算地球与空间科学研究中心）
Jets and Outflows in Young Stellar Objects with the SKAO
Leiden University（莱顿大学）；Univ. Grenoble Alpes（格勒诺布尔阿尔卑斯大学）；Sapienza University of Rome（罗马智慧大学）；Consiglio Nazionale delle Ricerche（意大利国家研究委员会）；Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理研究所）；SOKENDAI (The Graduate University for Advanced Studies)（日本综合研究大学院大学）；University of Leeds（利兹大学）；Academia Sinica（中央研究院）；National Institute of Science Education and Research（国家科学教育与研究机构）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；California Institute of Technology（加州理工学院）
Diverse stages of star formation in the IRAS 18162-2048 region. Emergence of UV Feedback
Instituto de Astrofísica de Andalucía, CSIC（安达卢西亚天体物理研究所，西班牙科学理事会）；INAF, Osservatorio Astronomico di Capodimonte（意大利国家天体物理研究所，卡波迪蒙特天文台）；Departament de Física Quàntica i Astrofísica (FQA), Universitat de Barcelona (UB)（巴塞罗那大学量子物理与天体物理学系）；Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (UB)（巴塞罗那大学宇宙科学研究所）；Thüringer Landessternwarte Tautenburg（图林根州陶滕堡天文台）；Instituto de Astronomía Teórica y Experimental (IATE), Universidad Nacional de Córdoba (UNC)（科尔多瓦国立大学理论与实验天体物理研究所）；Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México（墨西哥国立自治大学射电天文与天体物理研究所）
