2015/06/11 by Yurii Pidopryhora, Pidopryhora, Yurii, Felix J. Lockman +5
Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #astro-ph.GA
paper · pdf · doi:10.48550/arxiv.1506.03873
81 pages, 42 figures, accepted for publication in the Astrophysical Journal Supplement Series
arxiv created 2015/06/11 · arxiv updated 2015/06/15
A set of diffuse interstellar clouds in the inner Galaxy within a few hundred pc of the Galactic plane has been observed at an angular resolution of ~1 arcmin combining data from the NRAO Green Bank Telescope and the Very Large Array. At the distance of the clouds the linear resolution ranges from ~1.9 pc to ~2.8 pc. These clouds have been selected to be somewhat out of the Galactic plane and are thus not confused with unrelated emission, but in other respects they are a Galactic population. They are located near the tangent points in the inner Galaxy, and thus at a quantifiable distance: 2.3 ≤ R ≤ 6.0 kpc from the Galactic Center, and -1000 ≤ z ≤ +610 pc from the Galactic plane. These are the first images of the diffuse neutral HI clouds that may constitute a considerable fraction of the ISM. Peak HI column densities range from NHI = 0.8-2.9 × 1020 cm-2. Cloud diameters vary between about 10 and 100 pc, and their HI mass spans the range from less than a hundred to a few thousands Msun. The clouds show no morphological consistency of any kind except that their shapes are highly irregular. One cloud may lie within the hot wind from the nucleus of the Galaxy, and some clouds show evidence of two distinct thermal phases as would be expected from equilibrium models of the interstellar medium.