N-methylformamide, CH3NHCHO, may be an important molecule for interstellar pre-biotic chemistry because it contains a peptide bond. The rotational spectrum of the most stable trans conformer of CH3NHCHO is complicated by strong torsion-rotation interaction due to the low barrier of the methyl torsion. We use two absorption spectrometers in Kharkiv and Lille to measure the rotational spectra over 45--630 GHz. The analysis is carried out using the Rho-axis method and the RAM36 code. We search for N-methylformamide toward the hot molecular core Sgr B2(N2) using a spectral line survey carried out with ALMA. The astronomical results are put into a broader astrochemical context with the help of a gas-grain chemical kinetics model. The laboratory data set for the trans conformer of CH3NHCHO consists of 9469 line frequencies with J <= 62, including the first assignment of the rotational spectra of the first and second excited torsional states. All these lines are fitted within experimental accuracy. We report the tentative detection of CH3NHCHO towards Sgr B2(N2). We find CH3NHCHO to be more than one order of magnitude less abundant than NH2CHO, a factor of two less abundant than CH3NCO, but only slightly less abundant than CH3CONH2. The chemical models indicate that the efficient formation of HNCO via NH + CO on grains is a necessary step in the achievement of the observed gas-phase abundance of CH3NCO. Production of CH3NHCHO may plausibly occur on grains either through the direct addition of functional-group radicals or through the hydrogenation of CH3NCO. Provided the detection of CH3NHCHO is confirmed, the only slight underabundance of this molecule compared to its more stable structural isomer acetamide and the sensitivity of the model abundances to the chemical kinetics parameters suggest that the formation of these two molecules is controlled by kinetics rather than thermal equilibrium.
Tentative Detection of the Glycine Isomer Glycolamide in Hot Molecular Core
Chongqing University(重庆大学);Max Planck Institute for Astronomy(马克斯·普朗克天文学研究所);Xi’an Jiaotong-Liverpool University(西交利物浦大学);Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités(巴黎天文台,PSL研究大学,法国国家科学研究中心,索邦大学);GuangZhou University(广州大学)
The ALMA-PILS survey: First tentative detection of 3-hydroxypropenal (HOCHCHCHO) in the interstellar medium and chemical modeling of the C$_3$H$_4$O$_2$ isomers
Probing the chemical complexity of amines in the ISM: detection of vinylamine (C$_2$H$_3$NH$_2$) and tentative detection of ethylamine (C$_2$H$_5$NH$_2$)
胺,特别是伯胺(R-NH $_2$)与氨基酸的原始合成密切相关,因为它们共享相同的结构骨架。然而,在ISM中只确定了有限数量的胺,这阻止了我们研究它们的化学以及它们与可能导致生命出现的前生物物种的关系。在这封信中,我们报告了在银河系中心云G+0.693-0.027中首次星际探测到乙烯胺(C $_2$ H $_3$ NH $_2$)和乙胺(C $_2$ H $_5$ NH $_2$)。推导出的H $_2$丰度分别为(3.3 $\pm$ 0.4)$\times$ 10 $^{-10}$和(1.9 $\pm$ 0.5)$\times$ 10 $^{-10}$。C $_2$ H $_3$ NH $_2$和C $_2$ H $_5$ NH $_2$相对于甲胺(CH $_3$ NH $_2$)的推断丰度比分别为$\sim$ 0.02和$\sim$ 0.008。推导出的C $_2$ H $_3$ NH $_2$、C $_2$ H $_5$ NH $_2$和其他几个NH $_2$轴承物种的丰度进行了比较,对高质量和低质量的恒星形成区。根据最近的化学和实验室研究,可能的化学路线星际合成的C $_2$ H $_3$ NH $_2$和C $_2$ H $_5$ NH $_2$进行了讨论。
Centro de Astrobiología (CAB), CSIC-INTA(西班牙天体生物学中心(CAB),西班牙国家航空航天技术研究所与西班牙高等科学研究委员会联合);Universidad Complutense de Madrid(马德里康普顿斯大学);Astrophysik/I. Physikalisches Institut, Universität zu Köln(科隆大学第一物理研究所天体物理学部);Institut de Ciències de l’Espai (ICE), CSIC(空间科学研究所,西班牙高等科学研究委员会);Institut d’Estudis Espacials de Catalunya (IEEC)(加泰罗尼亚太空研究所);Department of Astronomy, University of Florida(佛罗里达大学天文系)
Toward a global model of the interactions in low-lying states of methyl cyanide: rotational and rovibrational spectroscopy of the $v_4 = 1$ state and tentative interstellar detection of the $v_4 = v_8 = 1$ state in Sgr B2(N)
通过对新的和已有的乙腈分子转动光谱的分析,将低振动态及其相互作用的整体模型推广到$v_4=1$(920 cm $^{-1}$).旋转光谱覆盖了36 $-$ 1439 GHz区域的大部分,并分别达到量子数$J$和$K$为79和16。CH $_3$ CN的$K$能级结构的信息由IR光谱获得。在我们以前的研究中分析的717 cm $^{-1}$周围的$2ν_8$光谱也覆盖了$ν_4$带。在这个波段的分配覆盖880 $-$ 952 cm $^{-1}$,获得的量子数$J$和$K$分别为61和13。$v_4=1$最重要的相互作用似乎是与$v_8=3$、$ΔK=0$、$Δl=+3$的相互作用,这是一种先前表征的非谐共振。我们报告了与$ΔK=-2$和$Δl=+1$,与$ΔK=-4$和$Δl=-1$,与$ΔK=-6$和$Δl=-3$相互作用的新分析;这四种类型的相互作用将$v_8=3$的所有$l$亚态能量连接到$v_4=1$。还分析了已知的$ΔK=-2$、$Δl=+1$与$v_7=1$的相互作用,并且改进了对$ΔK=+1$、$Δl=-2$和$ΔK=+3$、$Δl=0$与$v_8=2$的共振的研究,以及主要通过新的$v_8\le 2$旋转数据改进了连续状态与$v_8\le 3$之间的相互作用。基于转动跃迁频率和$ν_4+ν_8-ν_8$热带数据对$v_4=v_8=1$态进行了初步的单态分析。尽管$v…
A quest for sulfur-bearing refractory species. Identification of CaS in the interstellar medium
Centro de Astrobiología (CAB), CSIC-INTA(天体生物学中心(CAB),西班牙国家研究委员会-国家航空航天技术研究所);Institut de Ciències de l’Espai (ICE), CSIC(空间科学研究所(ICE),西班牙国家研究委员会);Institut d’Estudis Espacials de Catalunya (IEEC)(加泰罗尼亚空间研究学院(IEEC));Department of Astronomy, University of Florida(佛罗里达大学天文学系);I. Physikalisches Institut, Universität zu Köln(科隆大学第一物理研究所);Observatorio Astronómico Nacional (OAN)(国家天文台(OAN))
Expanding the C$_3$H$_6$O$_2$ Isomeric Interstellar Inventory: Discovery of Lactaldehyde and Methoxyacetaldehyde in G+0.693-0.027
Centro de Astrobiología (CAB), INTA-CSIC(天体生物学中心);Star and Planet Formation Laboratory, Pioneering Research Institute, RIKEN(理化学研究所前沿研究 institute 星与行星形成实验室);Departamento de Física de la Tierra y Astrofísica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid(马德里康普顿斯大学物理科学学院地球与天体物理学系)
A first taste of MEAD (Measuring Extinction and Abundances of Dust) -- I. Diffuse Milky Way interstellar dust extinction features in JWST infrared spectra
A Tentative Detection of Molecular Hydrogen (H$_2$) Emission Lines at Cosmic Dawn
Rutgers University(罗格斯大学);Center for Computational Astrophysics, Flatiron Institute(平顿研究所计算天体物理中心);Kavli Institute for Cosmology, University of Cambridge(剑桥大学卡弗里宇宙学研究所);Cavendish Laboratory, University of Cambridge(剑桥大学卡文迪许实验室);Technion—Israel Institute of Technology(以色列理工学院);LUX, Observatoire de Paris, Université PSL, Sorbonne Université, CNRS(巴黎天文台卢克斯实验室(巴黎文理研究大学、索邦大学、法国国家科学研究中心));Université Paris Cité(巴黎西岱大学);Department for Astrophysical and Planetary Science, University of Colorado, Boulder(科罗拉多大学博尔德分校天体物理学与行星科学系)
SPHEREx Pre-Perihelion Mapping of $\mathrm{H_2O}$, $\mathrm{CO_2}$, and $\mathrm{CO}$ in Interstellar Object 3I/ATLAS
Johns Hopkins University(约翰斯·霍普金斯大学);Johns Hopkins University Applied Physics Laboratory(约翰斯·霍普金斯大学应用物理实验室);Korea Astronomy and Space Science Institute (KASI)(韩国天文学与空间科学研究院);Jet Propulsion Laboratory, California Institute of Technology(加州理工学院喷气推进实验室);Department of Physics, California Institute of Technology(加州理工学院物理系);School of Earth and Space Exploration, Arizona State University(亚利桑那州立大学地球与空间探索学院);Department of Physics & Astronomy, University of California Irvine(加州大学欧文分校物理与天文系)