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Methanol formation chemistry with revised reactions scheme

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Research in Astronomy and Astrophysics 2020年第12期20卷 254-260页

作者： Valeriia Alekseevna Sokolova Ural Federal University 19 Mira streetYekaterinburg620002Russia Engineering Research Institute“Ventspils International Radio Astronomy Centre”of Ventspils University College Inzenieru 101VentspilsLV-3601Latvia

The aim of the presented work is to analyze the impact of experimentally evaluated reactions of hydrogen abstraction on surfaces of interstellar grains on the chemical evolution of methanol and its precursors on grains and in the gas phase under conditions of a cold dark cloud and during the collapse of a translucent cloud into a dark cloud. Analysis of simulation results shows that those reactions are highly efficient destruction channels for HCO and H2CO on grain surfaces, and significantly impact the abundances of almost all molecules participating in the formation of CH3OH. Next, in models with those reactions, maximum abundances of methanol in gas and on grain surfaces decrease by more than 2–3 orders of magnitude in comparison to models without surface abstraction reactions of hydrogen. Finally, we study the impact of binding energies of CH2OH and CH3O radicals on methanol chemistry.

关键词： astrochemistry ISM:molecules molecular processes chemical networks chemical modeling

GGCHEMPY: A Pure Python-based Gas-grain Chemical Code for Efficient Simulation of Interstellar Chemistry

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Research in Astronomy and Astrophysics 2022年第1期22卷 30-45页

作者： Jixing Ge Chinese Academy of Sciences South America Center for Astronomy National Astronomical ObservatoriesCASBeijing 100101China

In this paper,we present a new gas-grain chemical code for interstellar clouds written in pure Python(GGCHEMPY(GGCHEMPY is available on https://***/JixingGE/GGCHEMPY)).By combining with the high-performance Python compiler Numba,GGCHEMPY is as efficient as the Fortran-based *** the Python features,flexible computational workflows and extensions become *** a showcase,GGCHEMPY is applied to study the general effects of three-dimensional projection on molecular distributions using a two-core system which can be easily extended for more complex *** comparing the molecular distribution differences between two overlapping cores and two merging cores,we summarized the typical chemical differences such as N2 H+,HC3 N,C2 S,H2 CO,HCN and C2 H,which can be used to interpret 3 D structures in molecular clouds.

关键词： astrochemistry (ISM:)evolution ISM:molecules ISM:abundances methods:numerical

FAST Observations of Four Comets to Search for the Molecular Line Emissions between 1.0 and 1.5 GHz Frequencies

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Research in Astronomy and Astrophysics 2024年第10期24卷 130-140页

作者： Long-Fei Chen Chao-Wei Tsai Jian-Yang Li Bin Yang Di Li Yan Duan Chih-Hao Hsia Zhichen Pan Lei Qian Donghui Quan Xue-Jian Jiang Xiaohu Li Ruining Zhao Pei Zuo School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550025China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guiyang 550025China Research Center for Astronomical Computing Zhejiang LaboratoryHangzhou 311100China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Key Laboratory of Radio Astronomy and Technology Chinese Academy of SciencesBeijing 100101China School of Atmospheric Sciences Sun Yat-sen UniversityZhuhai 519082China Núcleo de Astronomía Facultad de Ingenieríay CienciasUniversidad Diego PortalesChile Department of Astronomy College of Physics and Electronic EngineeringQilu Normal UniversityJinan 250200China Department of Electronic and Optical Engineering Space Engineering UniversityBeijing 101416China Laboratory for Space Research Faculty of ScienceThe University of Hong KongHong Kong(SAR)China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China CAS Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China

We used the Five-hundred-meter Aperture Spherical radio Telescope(FAST)to search for the molecular emissions in the L-band between 1.0 and 1.5 GHz toward four comets,C/2020 F3(NEOWISE),C/2020 R4(ATLAS),C/2021 A1(Leonard),and 67P/Churyumov-Gerasimenko during or after their perihelion *** of molecular transition lines fall in this low-frequency range,many attributed to complex organic or prebiotic *** conducted a blind search for the possible molecular lines in this frequency range in those comets and could not identify clear signals of molecular emissions in the *** several molecules have been detected at high frequencies of greater than100 GHz in comets,our results confirm that it is challenging to detect molecular transitions in the L-band frequency *** non-detection of L-band molecular lines in the cometary environment could rule out the possibility of unusually strong lines,which could be caused by the masers or non-LTE *** the line strengths are predicted to be weak,for FAST,using the ultra-wide bandwidth receiver and improving the radio frequency interference environments would enhance the detectability of those molecular transitions at low frequencies in the future.

关键词： astrochemistry ISM:molecules comets:general line:identification

Laboratory study of the formation of fullerene(from smaller to larger, C44 to C70)/anthracene cluster cations in the gas phase

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Research in Astronomy and Astrophysics 2020年第12期20卷 299-306页

作者： De-Ping Zhang Yuan-Yuan Yang Xiao-Yi Hu Jun-Feng Zhen CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Quantum Information and Quantum Physics Hefei National Laboratory for Physical Sciences at the Microscaleand Department of Chemical PhysicsUniversity of Science and Technology of ChinaHefei 230026China

The formation and evolution mechanism of fullerenes in the planetary nebula or in the interstellar medium are still not ***,we present the study on the cluster formation and the relative reactivity of fullerene cations(from smaller to larger,C44 to C70) with anthracene molecule(C14H10).The experiment is performed in an apparatus that combines a quadrupole ion trap with a time-of-flight mass *** using a 355 nm laser beam to irradiate the trapped fullerenes cations(C60+or C70+),smaller fullerene cations C(60-2 n)+, n=1-8 or C(70-2 m)+,m=1-11 are generated,*** reacting with anthracene molecules,series of fullerene/anthracene cluster cations are newly formed(e.g.,(C14H10)C(60-2 n)+,n=1-8 and(C14H10)C(70-2 m)+,m=1-11),and slight difference of the reactivity within the smaller fullerene cations are ***,smaller fullerenes show obviously higher reactivity when comparing to fullerene C60+ and C70+.A successive loss of C2 fragments mechanism is suggested to account for the formation of smaller fullerene cations,which then undergo addition reaction with anthracene molecules to form the fullerene-anthracene cluster *** is found that the higher laser energy and longer irradiation time are key factors that affect the formation of smaller fullerene *** may indicate that in the strong radiation field environment(such as photon-dominated regions) in space,fullerenes are expected to follow the top-down evolution route,and then form small grain dust(e.g.,clusters) through collision reaction with co-existing molecules,here,smaller PAHs.

关键词： astrochemistry methods:laboratory ultraviolet:ISM ISM:molecules molecular processes

Study of Complex Nitrogen and Oxygen-bearing Molecules toward the High-mass Protostar IRAS 18089–1732

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Research in Astronomy and Astrophysics 2024年第6期24卷 81-93页

作者： Arijit Manna Sabyasachi Pal Tapas Baug Sougata Mondal Department of Physics Midnapore City CollegePaschim MedinipurWest Bengal721129India S.N.Bose National Centre for Basic Sciences Block-JDSector-IIISalt Lake CityKolkata700106 India

The observation of oxygen(O)-and nitrogen(N)-bearing molecules gives an idea about the complex prebiotic chemistry in the interstellar *** millimeter and submillimeter wavelength observations have shown the presence of complex O-and N-bearing molecules in the star formation ***,the investigation of those molecules is crucial to understanding the chemical complexity in the star-forming *** this article,we present the identification of the rotational emission lines of N-bearing molecules ethyl cyanide(C_(2)H_(5)CN)and cyanoacetylene(HC_(3)N),and O-bearing molecule methyl formate(CH_(3)OCHO)toward high-mass protostar IRAS18089–1732 using the Atacama Compact *** also detected the emission lines of both the N-and O-bearing molecule formamide(NH_(2)CHO)in the envelope of IRAS 18089–*** have detected the v=0 and 1 state rotational emission lines of CH_(3)*** also detected the two vibrationally excited states of HC_(3)N(v7=1 and v7=2).The estimated fractional abundances of C_(2)H_(5)CN,HC_(3)N(v7=1),HC_(3)N(v7=2),and NH_(2)CHO toward IRAS 18089–1732 are(1.40±0.5)×10^(-10),(7.5±0.7)×10^(-11),(3.1±0.4)×10^(-11),and(6.25±0.82)×10^(-11)***,the estimated fractional abundances of CH_(3)OCHO(v=0)and CH_(3)OCHO(v=1)are(1.90±0.9)×10^(-9)and(8.90±0.8)×10^(-10),*** also created the integrated emission maps of the detected molecules,and the observed molecules may have originated from the extended envelope of the *** show that C_(2)H_(5)CNand HC_(3)N are most probably formed via the subsequential hydrogenation of the CH_(2)CHCNand the reaction between C_(2)H_(2)and CN on the grain surface of IRAS 18089–*** found that NH_(2)CHO is probably produced due to the reaction between NH_(2)and H_(2)CO in the gas ***,CH_(3)OCHO is possibly created via the reaction between radical CH_(3)O and radical HCO on the grain surface of IRAS 18089–1732.

关键词： ISM:individual objects(IRA 18089-1732)(except) ISM:abundances ISM:kinematics and dynamics stars:formation astrochemistry

ALMA and GMRT Studies of Dust Continuum Emission and Spectral Lines Toward Oort Cloud Comet C/2022 E3(ZTF)

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Research in Astronomy and Astrophysics 2024年第12期24卷 81-92页

作者： Arijit Manna Sabyasachi Pal Sekhar Sinha Sushanta Kumar Mondal Department of Physics and Astronomy Midnapore City College Department of Physics Sidho-Kanho-Birsha University

The atomic and molecular compounds of cometary ices serve as valuable knowledge into the chemical and physical properties of the outer solar nebula, where comets are formed. From the cometary atmospheres, the atoms and gas-phase molecules arise mainly in three ways:（i） the outgassing from the nucleus,（ii） the photochemical process, and（iii） the sublimation of icy grains from the nucleus. In this paper, we present the radio and millimeter wavelength observation results of Oort cloud non-periodic comet C/2022 E3（ZTF） using the Giant Metrewave Radio Telescope（GMRT） band L and the Atacama Large Millimeter/submillimeter Array（ALMA） band 6. We do not detect continuum emissions and an emission line of atomic hydrogen（H I） at rest frequency 1420 MHz from this comet using the GMRT. Based on ALMA observations, we detect the dust continuum emission and rotational emission lines of methanol（CH3OH） from comet C/2022 E3（ZTF）. From the dust continuum emission, the dust production（Afρ） activity of comet ZTF is 2280 ± 50 cm. Based on LTE spectral modeling, the column density and excitation temperature of CH3OH toward C/2022 E3（ZTF） are（4.50 ± 0.25） × 1014cm-2and 70 ± 3 K respectively. The integrated emission maps show that CH3OH was emitted from the coma region of the comet. The production rate of CH3OH toward C/2022 E3（ZTF） is（7.32 ± 0.64） × 1026molecules s-1. The fractional abundance of CH3OH with respect to H2O in the coma of the comet is 1.52%. We also compare our derived abundance of CH3OH with the existence modeled value, and we see the observed and modeled values are quite similar. We claim that CH3OH is formed via the subsequential hydrogenation of formaldehyde（H2CO） on the grain surface of comet C/2022 E3（ZTF）.

关键词： astrochemistry Comets: general Planets and satellites: composition Radio continuum: planetary systems Submillimeter: planetary systems

Understanding the Impact of H_(2) Diffusion Energy on the Formation Efficiency of H_(2) on the Interstellar Dust Grain Surface

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Research in Astronomy and Astrophysics 2024年第9期24卷 190-198页

作者： Xiaoying Guo Wasim Iqbal Qiang Chang Xiao-Hu Li School of Physics and Optoeletronic Engineering Shandong University of TechnologyZibo 255000China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Key Laboratory of Radio Astronomy Chinese Academy of SciencesUrumqi 830011China

We use microscopic Monte Carlo simulation techniques to investigate the impact of H_(2)diffusion energy on the recombination efficiency of H_(2)on interstellar dust grain surfaces under diffuse and translucent cloud *** constructed five models representing different possible conditions encountered by adsorbed H and H_(2)on interstellar dust *** implemented adsorption sites with multiple binding energies for surface species;the Encounter-Desorption mechanism was also *** study focused on silicate surfaces in diffuse clouds and water ice surfaces in translucent *** results show that the recombination efficiency of H_(2)on dust surfaces decreases as H_(2)diffusion energy *** interesting finding of this work is that considering different binding sites for H and H_(2)gives rise to multiple steady phases,during which the recombination efficiency remains constant with a change in H_(2)diffusion energy.

关键词： astrochemistry atomic processes ISM:molecules

Theoretical approach to study the formation of C2H4O2 isomers in interstellar medium through reaction between interstellar formaldehyde molecules

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Research in Astronomy and Astrophysics 2020年第1期20卷 124-136页

作者： Aftab Ahmad Shivani Alka Misra Poonam Tandon Department of Mathematics&Astronomy University of LucknowLucknowIndia Department of Physics University of LucknowLucknowIndia

The three isomers of C2H4O2,viz.,glycolaldehyde(HCOCH2 OH),acetic acid(CH3 COOH)and methyl formate(HCOOCH3),have been detected in copious amounts in the interstellar medium(ISM).The possibility for formation of these molecules through interstellar formaldehyde(HCHO)has been explored by using the quantum chemical approach described by density functional theory(DFT)and second order Moller-Plesset perturbation(MP2)theory with a 6–311 G(d,p)basis set in the gas phase as well as in icy *** associated molecule-molecule interactions have been discussed to study the formation of isomers of C2H4O2 in *** reactions of two formaldehyde molecules exhibit a considerable potential barrier but due to quantum tunneling,these reactions could be possible in *** chemical pathway is exothermic,which gives rise to a high probability for the formation of all three isomers,***,methyl formate and acetic acid,in interstellar *** rotational vibration,centrifugal distortion constants and coupling constants are also calculated and results suggest that the vibrations are harmonic in nature.

关键词： ISM:molecules astrochemistry astrobiology abundances

Chempl: a playable package for modeling interstellar chemistry

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Research in Astronomy and Astrophysics 2021年第3期21卷 261-271页

作者： Fujun Du Purple Mountain Observatory and Key Laboratory of Radio Astronomy Chinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China

Astrochemical modeling is needed for understanding the formation and evolution of interstellar molecules,and for extracting physical information from spectroscopic observations of interstellar *** modeling usually involves the handling of a chemical reaction network and solution of a set of coupled nonlinear ordinary differential equations,which is traditionally done using code written in compiled languages such as Fortran or C/C++.While being computationally efficient,there is room for improvement in the ease of use and interactivity for such an *** this work we present a new public code named CHEMPL,which emphasizes interactivity in a modern Python environment,while remaining computationally *** reaction mechanisms and a three-phase formulation of gasgrain chemistry are implemented by *** is straightforward to run 0 D models with CHEMPL,and only a small amount of additional code is needed to construct 1 D or higher-dimensional chemical *** demonstrate its usage with a few astrochemically relevant examples.

关键词： astrochemistry methods:numerical ISM:evolution ISM:molecules