Resolved Atomic Super-clouds in Spiral Galaxies

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dc.creatorBraun, Robert
dc.date1995-12-13
dc.date.accessioned2026-07-07T02:20:36Z
dc.date.available2026-07-07T02:20:36Z
dc.descriptionHigh quality data are presented of neutral hydrogen emission and absorption in the fields of eleven of the nearest spiral galaxies. Multi-configuration VLA observations have provided angular resolution of 6~arcsec (corresponding to about 100~pc at the average galaxy distance of 3.5~Mpc) and velocity resolution of 6~km~s$^{-1}$, while accurately recovering the total line flux detected previously with filled apertures. Previous experience suggests that this physical resolution is sufficient to at least marginally resolve the \ion{H}{1} super-cloud population which delineates regions of active star formation. A high brightness filamentary network of \ion{H}{1} super-clouds is seen in each galaxy. Emission brightness temperatures in excess of 200~Kelvin are sometimes detected at large radii, even in relatively face-on systems. All galaxies display a systematic increase in the observed brightness temperature of super-clouds with radius, followed by a flattening and subsequent decline. In the few instances where background continuum sources allow detection of \ion{H}{1} absorption, the indicative spin temperatures are consistent with the super-cloud brightness temperature seen in emission at similar radii. These data suggest substantial opacity of the \ion{H}{1} in the super-cloud network.
dc.description11 page LaTeX requires aastex style files version 4. Hardcopies of 11 figures available from the author on request. To appear in Astr.Astroph.Suppl., December II 1995
dc.identifierhttps://arxiv.org/abs/astro-ph/9512085
dc.identifierhttp://arxiv.org/abs/astro-ph/9512085
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/10261
dc.subjectAstrophysics
dc.titleResolved Atomic Super-clouds in Spiral Galaxies
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