Title: The mixing of dust and gas in the high latitude translucent cloud MBM 40 Show Chinese title

Title: 尘埃和气体在高纬度半透明云MBM 40中的混合

Abstract: Context. High latitude molecular clouds (hereafter HLMCs) permit the study of interstellar gas dynamics and astrochemistry with good accuracy due to their proximity, generally clear lines of sight, and lack of internal star-forming activity which can heavily modify the physical context. MBM 40, one of the nearest HLMCs, has been extensively studied, making it a superb target to infer and study the dust-to-gas mixing ratio (DGMR). Aims. The mixing of dust and gas in the interstellar medium remains a fundamental issue to keep track of astrochemistry evolution and molecular abundances. Accounting for both molecular and atomic gas is difficult because $H_2$ is not directly observable and HI spectra always show different dynamical profiles blended together which are not directly correlated with the cloud. We used two independent strategies to infer the molecular and atomic gas column densities and compute the dust-to-gas mixing ratio. Methods. We combined $HI$ 21 cm and $^{12}CO$ line observations with the IRAS 100 $\mu$m image to infer the dust-to-gas mixing ratio within the cloud. The cloud 21 cm profile was extracted using a hybrid Gaussian decomposition where $^{12}CO$ was used to deduce the total molecular hydrogen column density. Infrared images were used to calculate the dust emission. Results. The dust-to-gas mixing ratio is nearly uniform within the cloud as outlined by the hairpin structure. The total hydrogen column density and 100 $\mu$m emissivity are linearly correlated over a range in $N(H_{tot})$ of one order of magnitude. Show Chinese abstract

Abstract: 上下文。 高纬度分子云（以下简称HLMCs）由于其接近性、通常清晰的视线以及缺乏内部恒星形成活动，可以较为准确地研究星际气体动力学和天体化学。 MBM 40是最近的HLMCs之一，已被广泛研究，使其成为推断和研究尘埃与气体混合比（DGMR）的理想目标。 目的。 星际介质中尘埃和气体的混合仍然是跟踪天体化学演化和分子丰度的基本问题。 同时考虑分子和原子气体是困难的，因为$H_2$无法直接观测，HI光谱总是显示出不同动力学轮廓的混合，这些轮廓与云本身没有直接相关性。 我们使用了两种独立策略来推断分子和原子气体柱密度并计算尘埃与气体混合比。 方法。 我们将$HI$21厘米和$^{12}CO$线观测与IRAS 100$\mu$米图像结合，以推断云中的尘埃与气体混合比。 通过一种混合高斯分解方法提取了云的21厘米轮廓，其中$^{12}CO$被用于推导总分子氢柱密度。 红外图像用于计算尘埃发射。 结果。 如发夹结构所示，云中的尘埃与气体混合比几乎是均匀的。 总氢柱密度和100$\mu$米发射率在$N(H_{tot})$的一个数量级范围内呈线性相关。