Nuclear Resonances: The quest for large column densities and a new tool

从分子云的柱密度估计数密度的概率模型

A Probabilistic Model to Estimate Number Densities from Column Densities in Molecular Clouds

提出一种概率模型，将分子云视线方向的总氢核柱密度分解为湍流和引力主导分量，从而从柱密度图估计局部数密度，并成功应用于预测Taurus等云的谱线发射。

A fast tree-based method for estimating column densities in Adaptive Mesh Refinement codes Influence of UV radiation field on the structure of molecular clouds

Context. Ultraviolet radiation plays a crucial role in molecular clouds. Radiation and matter are tightly coupled and their interplay influences the physical and chemical properties of gas. In particular, modeling the radiation propagation requires calculating column densities, which can be numerically expensive in high-resolution multidimensional simulations. Aims. Developing fast methods for estimating column densities is mandatory if we are interested in the dynamical influence of the radiative transfer. In particular, we focus on the effect of the UV screening on the dynamics and on the st…

disnht: modeling X-ray absorption from distributed column densities

Collecting and analysing X-ray photons over either spatial or temporal scales encompassing varying optical depth values requires knowledge about the optical depth distribution. In the case of sufficiently broad optical depth distribution, assuming a single column density value leads to a misleading interpretation of the source emission properties, nominally its spectral model. We present a model description for the interstellar medium absorption in X-ray spectra at moderate energy resolution, extracted over spatial or temporal regions encompassing a set of independent column densities. The abs…

局部星际介质中的硫X射线吸收

Sulfur X-ray absorption in the local ISM

本研究利用Chandra高分辨率光谱分析36个低质量X射线双星的硫K边吸收，估计多种硫离子及尘埃柱密度，发现其随银纬变化但与距离和银经无相关性，为首次此类详细分析。

A New Recipe for Obtaining Central Volume Densities of Prestellar Cores from Size Measurements

We propose a simple analytical method for estimating the central volume density of prestellar molecular cloud cores from their column density profiles. Prestellar cores feature a flat central part of the column density and volume density profiles of the same size indicating the existence of a uniform density inner region. The size of this region is set by the thermal pressure force which depends only on the central volume density and temperature of the core, and can provide a direct measurement of the central volume density. Thus a simple length measurement can immediately yield a central dens…

从吸收双线的等效宽度估计柱密度

Column-Density Estimation from the Equivalent Widths of Absorption Doublets

该研究提出从吸收双线等效宽度估计柱密度的分析框架，无需分辨速度结构，给出高斯生长曲线相关反演方法及严格下界，经Ia型超新星数据验证，可转换为消光估计并附公开实现。