Despite its potential reactivity due to ring strain, ethylene oxide (c-C2H4O) is a complex molecule that seems to be stable under the physical conditions of an interstellar dense core; indeed it has been detected towards several high-mass star forming regions with a column density of the order of 10e13cm-2 (Ikeda et al. 2001). To date, its observational abundances cannot be reproduced by chemical models and this may be due to the significant contribution played by its chemistry on grain surfaces. Recently, Ward and Price (2011) have performed experiments in order to investigate the surface formation of ethylene oxide starting with oxygen atoms and ethylene ice as reactants. We present a chemical model which includes the most recent experimental results from Ward and Price (2011) on the formation of c-C2H4O. We study the influence of the physical parameters of dense cores on the abundances of c-C2H4O. We verify that ethylene oxide can indeed be formed during the cold phase (when the ISM dense cores are formed), via addition of an oxygen atom across the C=C double bond of the ethylene molecule, and released by thermal desorption during the hot core phase. A qualitative comparison between our theoretical results and those from the observations shows that we are able to reproduce the abundances of ethylene oxide towards high-mass star-forming regions.
Chemical modelling of dust-gas chemistry within AGB outflows -- II. Effect of the dust-grain size distribution
AGB星和超新星是构成星际介质的主要物质。AGB星形成的尘埃颗粒被认为很大。然而,由于尘埃在其流出物中的成核和生长仍然不清楚,尘埃粒度分布(GSD)是未知的。这是一个重要的不确定性,我们的知识的化学和物理历史的星际尘埃,作为AGB尘埃形式的$\sim$ 70%的起点,其演变。我们扩展了我们的化学动力学模型,其中包括一个全面的粉尘-气体化学。现在允许GSD偏离通常假设的标准Mathis et al.(1977)分布。我们发现,特定的GSD可以显着影响内流出的粉尘-气体化学。我们的研究结果表明,耗尽的气相物种的水平取决于平均晶粒表面积的GSD。当使用一系列跃迁时,可以从分子发射线的观测中检索气相丰度分布及其可能的耗尽。由于GSD处方内的简并性,无法检索特定参数,仅检索平均晶粒表面积(下限)。尽管如此,这可以区分主要由大颗粒或小颗粒组成的灰尘。我们表明,当结合其他可观测的,如光谱能量分布和偏振光,耗尽水平从分子气相丰度分布可以限制难以捉摸的GSD的尘埃AGB流出到ISM。
Photoionization modelling of circumstellar nebulae using irregular grains
Instituto de Astrofísica de Andalucía (IAA-CSIC)(安达卢西亚天体物理学研究所);Universidad Nacional Autónoma de México. Instituto de Astronomía(墨西哥国立自治大学天文研究所);Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México(墨西哥国立自治大学射电天文学与天体物理研究所)
Grain alignment and dust evolution physics with polarisation (GRADE-POL). I. Dust polarisation modelling for isolated starless cores
Leiden University(莱顿大学);Max-Planck-Institut für Radioastronomie(马克斯·普朗克射电天文研究所);Korea Astronomy and Space Science Institute(韩国天文学与空间科学研究所);University of Science and Technology(科学技术大学);University of Wisconsin-Madison(威斯康星大学麦迪逊分校);Universität zu Köln(科隆大学);University of Texas at Austin(德克萨斯大学奥斯汀分校);Massachusetts Institute of Technology(麻省理工学院);Vietnam National Space Center, Vietnam Academy of Science and Technology(越南国家航天中心,越南科学技术院);Graduate University of Science and Technology, Vietnam Academy of Science and Technology(越南科学技术院高等科学学院);National Chung Hsing University(国立中兴大学)
Synthetic Modelling of Polarized Dust Emission in Intermediate-Mass YSOs: II: Effects of Radiative Torque Disruption on Dust Grains in Protostellar Jets/Outflows
Korea Astronomy and Space Science Institute(韩国天文与空间科学研究所);University of Science and Technology(科学技术大学);NASA Ames Research Center(美国宇航局艾姆斯研究中心);Institute of Space Sciences (ICE), CSIC(空间科学研究所(ICE),西班牙高等科学研究委员会);ICREA(加泰罗尼亚高级研究学院);AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité(天体物理与分子研究所(AIM),法国原子能与替代能源委员会(CEA),法国国家科学研究中心(CNRS),巴黎萨克雷大学,巴黎第七大学,索邦巴黎城市)
Modelling the evolution and influence of dust in cosmological simulations that include the cold phase of the interstellar medium
University of Portsmouth(朴茨茅斯大学);Leiden University(莱顿大学);University of Vienna(维也纳大学);University of Hull(赫尔大学);Lorentz Institute for Theoretical Physics, Leiden University(莱顿大学洛伦兹理论物理研究所);University of Milano-Bicocca(米兰比可卡大学);Durham University(杜伦大学)
Synthetic Modelling of Polarized Dust Emission in Intermediate-Mass YSOs: I: Constraining the Role of Iron Inclusions and Inelastic Relaxation on Grain Alignment with ALMA Polarization
JWST observations of photodissociation regions III. Dust modelling at the illuminated edge of the Horsehead PDR
Institut d'Astrophysique Spatiale (IAS), Université Paris Saclay(太空天体物理研究所,巴黎萨克雷大学);Space Telescope Science Institute (STScI)(空间望远镜科学研究所);Institut de Recherche en Astrophysique et Planétologie (IRAP)(天体物理学与行星学研究所以);Chalmers University of Technology(查尔姆斯理工大学);University of Helsinki(赫尔辛基大学);University of Arizona(亚利桑那大学);Sorbonne Université(索邦大学);Institut d'Astrophysique de Paris (IAP)(巴黎天体物理研究所);University of Toledo(托莱多大学);Universiteit Gent(根特大学);Université Paris Cité(巴黎西岱大学);Leiden University(莱顿大学);Royal Observatory Edinburgh(爱丁堡皇家天文台);The University of Western Ontario(韦仕敦大学(西安大略大学))
Thermal formation of ammonium carbamate on the surface of laboratory analogues of carbonaceous grains in protostellar envelopes and planet-forming disks
The Role of Radiolysis in the Modelling of C$_{2}$H$_{4}$O$_{2}$ Isomers and Dimethyl Ether in Cold Dark Clouds
复杂有机分子(COMs)已经在各种星际源中被探测到。这些COMs在变暖源中的丰度可以通过与温度和密度增加有关的合成来解释,允许准热化学反应足够迅速地发生,以产生可观察到的COMs数量,无论是在气相中,还是在尘埃颗粒冰幔上。当温度升高到足以允许它们的热解吸时,在晶粒上产生的COM然后变成气态。最近在冷源中观测到的气态COMs还不能完全用这些气相和尘埃颗粒的产生途径来解释。辐解化学是一种可能的非热方法生产COM冷暗云。这种新方法大大增加了模拟丰富的选定的COM上的冰表面和冰地幔内由于宇宙射线轰击的激发和电离事件。我们研究了辐射分解对三种C $_{2}$ H $_{4}$ O $_{2}$异构体--甲酸甲酯(HCOOCH $_3$)、乙醇醛(HCOCH $_2$ OH)和乙酸(CH $_3$ COOH)--以及一种化学性质相似的分子二甲醚(CH $_3$ OCH $_3$)在寒冷的乌云中的影响。然后,我们将我们模拟的气体丰度与TMC-1,L1689 B和B1-b中观测到的丰度进行比较。