Computational chemistry is used here to build a set of carbonaceous structures whose combined spectra approximately mimic typical UIB (Unidentified Infrared Band) spectra. A large number of relatively small hydrocarbon structures, containing traces of heteroatoms (oxygen, nitrogen and sulfur) were considered, including aliphatic chains, compact and concatenated hexagonal and pentagonal rings. Their ir (infrared) spectra were computed using standard chemistry software. Those which exhibited at least a few lines falling within one of the UIBs, and no significantly strong line outside the observed bands, were retained: in all 35 structures, grouped in 8 families and totalling about 6000 vibrational modes together. Each family exhibits a characteristically different spectrum. Guided by the IRS spectra of the Spitzer satellite, each of the 8 families was given a weight, which was tailored so that the concatenation of all 35 weighted spectra resembled UIB spectra. A typical chemical composition is found to be C:H:O:N:S=1:1.15:0.064:0.0026:0.013. The present procedure allows each structural family to be preferentially assigned to an observed UIB, which helps figuring out the structure of interstellar dust. The essential role of heteroatoms is apparent.
Numerical Models for the Diffuse Ionized Gas in Galaxies. I. Synthetic spectra of thermally excited gas with turbulent magnetic reconnection as energy source
Exploring the mid-infrared SEDs of six AGN dusty torus models I: synthetic spectra
在远离活动星系核（AGN）的地方，环境温度低于1500-1800 K，尘埃能够存活。因此，有可能存在一个围绕活动星系核的大尘埃结构。这是两篇论文中的第一篇，旨在比较六个尘埃环面模型与可用的SED，即Fritz et al.（2006），Nenkova et al.（2008 B），Hoenig & Kishimoto（2010），Siebenmorgen et al.（2015），Stalevski et al.（2016）和Hoenig & Kishimoto（2017）。在这第一篇论文中，我们使用合成光谱来探索这些模型之间的区别，在何种情况下，他们允许限制环面参数，而我们的第二篇论文分析了最好的模型来描述中红外光谱数据。我们已经产生了合成光谱，从目前的仪器：GTC/CanariCam和斯皮策/IRS和未来的JWST/MIRI和JWST/NIRSpec仪器。我们发现，对于一个合理的亮度（F12 um> 100 mJy），我们实际上可以区分模型之间，除了两对父模型。我们表明，这些模型可以区分的基础上的连续斜率和强度的硅酸盐功能。此外，对于除Hoenig & Kishimoto（2017）之外的所有模型，无论使用何种仪器，其参数都可以限制在15%的误差范围内。然而，当超过50%的环核贡献者被包括在内时，参数估计被破坏。因此，未来的高空间分辨率光谱，如那些预期从JWST将提供足够的覆盖…
Models of Metal-Poor Stars with Different Initial Abundances of C, N, O, Mg, and Si. I. Bolometric Corrections Derived from New MARCS Synthetic Spectra and Their Implications for Observed Colour-Magnitude Diagrams
新的，高分辨率的MARCS合成光谱已经计算了十几种金属的混合物，允许，反过来，在C：N：O，[CNO/Fe]的变化，和C，O，Mg和Si的丰度增加。目前使用的许多宽带滤波器的辐射热校正（BC）已经从这些光谱中产生。由于改进的处理分子，涉及原子的C，N和O，紫外线和蓝色通带的BC，特别是，从以前的MARCS模型中得到的那些有很大的不同。这些差异，以及不同的金属丰度对BC的影响，在一些指导性的图中显示。还计算了不同混合物在-2.5 <= [Fe/H] <= -0.5时的恒星演化网格。基于这些径迹的等时线在理论H-R图和几个颜色-星等图上进行了相互比较，这些颜色-星等图可以由HST Wide Field Camera 3（WFC 3）F336 W、F438 W、F606 W、F814 W、F110 W和F160 W观测值构造。作为这些模型的首次应用，等时线已被拟合到HST紫外遗产巡天球状星团NGC 6496的WFC 3测光中，得到了非常令人鼓舞的结果。
Estimating Photometric Distances to Ultracool Dwarfs in Next Generation Space-based Infrared Surveys: Synthetic Photometry and New Absolute Magnitude Versus Spectral Type Relations for JWST, Euclid, and Roman Filters
