Tiny-Scale Molecular Structures in the Magellanic Clouds (Part 1)

Abstract

We report on the {\small FUSE} detections of the HD and CO molecules {\bf on the lines of sight towards three Large Magellanic stars}: Sk $-$67D05, Sk $-$68D135, and Sk $-$69D246. HD is also detected for the first time {\bf on the lines of sight towards two Small Magellanic Cloud stars}: AV 95 and Sk 159. While the HD and CO abundances are expected to be lower in the Large Magellanic Cloud where molecular fractions are a third of the Galactic value and where the photodissociation flux is up to thousands times larger, we report an average HD/H${}_2$ ratio of 1.4$\pm$0.5 ppm and CO/H${}_2$ ratio ranging from 0.8 to 2.7 ppm similar to the Galactic ones. We tentatively identify a deuterium reservoir (hereafter D--reservoir) towards the Small Magellanic Cloud, along the light path to AV 95. We derive a D/H ratio ranging from 1. 10${}^{-6}$ to 1.1 10${}^{-5}$.

34 pages, 10 tables, 12 figures, accepted for publication in A&A

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• Physical conditions in the neutral interstellar medium at z=2.43 toward Q2348-011
• Deuterated molecular hydrogen in the Galactic ISM. New observations along seven translucent sightlines
• Molecular hydrogen in damped Ly-alpha systems: clues to interstellar physics at high-redshift
• Galaxies Probing Galaxies in PRIMUS - II. The Coherence Scale of the Cool Circumgalactic Medium
• Thermal Pressures in the Interstellar Medium of the Magellanic Clouds
• Studying the small scale ISM structure with supernovae
• Detection of Interstellar C_2 and C_3 in the Small Magellanic Cloud
• Interstellar Ti II in the Milky Way and Magellanic Clouds
• The structure function of Galactic \HI opacity fluctuations on AU scales based on MERLIN, VLA and VLBA data
• FUSE observations of molecular hydrogen on the line of sight towards HD141569A
• Large and small-scale structure of the Intermediate and High Velocity Clouds towards the LMC and SMC
• Microlensing by gas filaments
• First detections of CO absorption in the Magellanic Clouds and direct measurement of the CO-to-H${}_2$ ratio