The ratio between the two stable isotopes of nitrogen, $^{14}$N and $^{15}$N, is well measured in the terrestrial atmosphere ($\sim 272$), and in the pre-Solar nebula ($\sim 441$). Interestingly, some pristine Solar System materials show enrichments in $^{15}$N with respect to the pre-Solar nebula value. However, it is not yet clear if, and how, these enrichments are linked to the past chemical history, due to the limited number of measurements in dense star-forming regions. In this respect, dense cores believed to be precursors of clusters containing also intermediate- and high-mass stars are important targets, as the Solar System was probably born within a rich stellar cluster. In this work, we show the results of IRAM-30m observations of the J=1-0 rotational transition of the molecules HCN and HNC, and their $^{15}$N-bearing counterparts, towards 27 intermediate/high-mass dense cores divided in three evolutionary categories: high-mass starless cores, high-mass protostellar objects, and ultra-compact HII regions. We have also observed the DNC(2-1) rotational transition, in order to search for a relation between the isotopic ratios D/H and $^{14}$N/$^{15}$N. We derive average $^{14}$N/$^{15}$N ratios of $359\pm16$ in HCN and of $438\pm21$ in HNC, with a dispersion of about 150-200. We find no trend of the $^{14}$N/$^{15}$N ratio with the evolutionary stage. This result agrees with what found from N$_{2}$H$^{+}$ and its isotopologues in the same sources, although the $^{14}$N/$^{15}$N ratios from N$_{2}$H$^{+}$ show a dispersion larger than that in HCN/HNC. Moreover, we have found no correlation between D/H and $^{14}$N/$^{15}$N in HNC. These findings indicate that: (1) the chemical evolution does not seem to play a role in the fractionation of nitrogen; (2) the fractionation of hydrogen and nitrogen in these objects are not related.
Quantum and Structural Effects Captured via a Statistical Method: the SACM Applied to HCN and HNC Colliding with CO
Univ. Rennes, CNRS, IPR (Institut de Physique de Rennes), UMR 6251（雷恩大学）；Department of Chemistry, Missouri University of Science and Technology（密苏里科技大学）
SMA Observations Reveal Abundant HNC Chemistry in Transition Disks
University of Virginia（弗吉尼亚大学）；University of Texas San Antonio（德克萨斯大学圣安东尼奥分校）；Southwest Research Institute（西南研究院）；University of Arizona（亚利桑那大学）；The University of Tokyo（东京大学）；University of California, Berkeley（加州大学伯克利分校）；Université Grenoble Alpes（格勒诺布尔阿尔卑斯大学）
High Resolution Overtone Spectroscopy of HNC$^+$ and HCN$^+$
Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理研究所）；School of Chemistry, University of Edinburgh（爱丁堡大学化学学院）；Stavropoulos Center for Complex Quantum Matter, Department of Physics and Astronomy, University of Notre Dame（圣母大学斯塔夫罗普洛斯复杂量子物质中心）；Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University（查理大学数学与物理学院表面与等离子体科学系）
A tale of two isotopes: Spatial variation in HCN fractionation toward young cores
Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）；Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心（CAB），西班牙国家科学研究委员会-国家航空技术研究所）；European Southern Observatory（欧洲南方天文台）
Molecules with ALMA at Planet-forming Scales (MAPS). X. Studying deuteration at high angular resolution toward protoplanetary disks
氘分馏取决于各种物理和化学参数。因此，太阳系中物质的形成位置和热历史往往是通过测量其D/H比来研究的。这就需要了解行星形成时期的氘化过程。我们的目标是研究这些过程，通过径向分辨DCN/HCN（在0.3”分辨率）和N $_2$ D $^+$ /N $_2$ H $^+$（0.3至0.9”）柱密度比对五个原行星盘观测的分子与ALMA在行星形成尺度（MAPS）大计划。在所有五个来源中检测到DCN，其中一个是新报告的检测。N $_2$ D $^+$在四个来源中检测到，其中两个是新报告的检测。我们推导出柱密度分布，使我们能够在高分辨率下研究DCN/HCN和N $_2$ D $^+$ /N $_2$ H $^+$比率的空间变化。DCN/HCN对于磁盘的不同部分变化很大，范围从$10^{-3}$到$10^{-1}$。特别是，与外盘相比，内盘区域通常显示出显著较低的HCN氘代。此外，我们的分析证实，两个氘分馏通道是活跃的，这可以改变的D/H比内池的有机分子。在$\sim$ 50 au以外的冷外部区域发现了N $_2$ D $^+$，在整个盘样品中，N $_2$ D $^+$ /N $_2$ H $^+$的范围在$10^{-2}$和1之间。这与理论预期的N $_2$ H $^+$氘化仅通过低温通道进行是一致的。本文是《天体物理学杂志增刊》MAPS特刊的一部分。
