1998/09/14 by J. T. Lauroesch, David M. Meyer, John K. Watson +2 · 2 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Atomic and Molecular Physics #Context (archaeology) #Galaxy #Hubble space telescope #Interstellar cloud #Interstellar medium #Line (geometry) #Molecular cloud #Physics #Space Telescope Imaging Spectrograph #Spectral line #Spectrograph #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/311677
10 pages, 2 figures, to appear in the Astrophysical Journal (Letters)
arxiv created 1998/09/14 · openalex publication_date 1998/11/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present Hubble Space Telescope Goddard High Resolution Spectrograph echelle observations of multiple interstellar lines of C I, Mg I, Cr II, and Zn II toward both stars in the μ Crucis binary system. Despite large differences in the profiles of the neutral species, no significant variations between the stars are seen in the Cr II and Zn II line profiles. In particular, the Zn II absorption observed at -8.6 km s -1 toward μ Cru is constant despite greatly enhanced columns of the neutral species at this velocity toward μ 1 Cru. An analysis of the fine-structure excitation of C I in this cloud implies that the density is n <250 cm −3 . From the lack of variation in the (optical) Na I D2 line profiles toward μ 1 and μ 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.