标题： 缪十字星的微尺度星际结构的物理特性 显示英文标题

标题： The Physical Characteristics of the Small-Scale Interstellar Structure towards Mu Crucis

摘要： 我们呈现了HST/GHRS阶梯光谱对mu Cru双星系统中两个恒星的多个星际线CI、MgI、CrII和ZnII的观测结果。尽管中性物种的轮廓存在显著差异，但在CrII和ZnII线轮廓中未观察到恒星之间的显著变化。特别是，朝向mu Cru在-8.6 km/sec处观测到的ZnII吸收在该速度下朝向mu^1 Cru的中性物种柱密度显著增强的情况下仍保持恒定。对该云中CI的精细结构激发的分析表明，密度为n_H < 250 cm^{-3}。从在相隔21个月拍摄的光谱中朝向mu^1和mu^2 Cru的（光学）NaI D2线轮廓缺乏变化，我们可以对结构的大小设定下限约为10 AU。这些结果结合最近的射电和光学研究中关于明显普遍的高密度小尺度星际结构进行了讨论。 显示英文摘要

摘要： We present HST/GHRS echelle observations of multiple interstellar lines of CI, MgI, CrII, and ZnII towards both stars in the mu Cru binary system. Despite large differences in the profiles of the neutral species, no significant variations between the stars are seen in the CrII and ZnII line profiles. In particular, the ZnII absorption observed at -8.6 km/sec towards mu Cru is constant despite greatly enhanced columns of the neutral species at this velocity towards mu^1 Cru. An analysis of the fine-structure excitation of CI in this cloud implies that the density is n_H < 250 cm^{-3}. From the lack of variation in the (optical) NaI D2 line profiles towards mu^1 and mu^2 Cru in spectra taken 21 months apart, we can place a lower limit to the size of the structures of ~10 AU. These results are discussed in the context of recent radio and optical studies of apparently pervasive high density small-scale interstellar structure.