The physics of the galactic halo gas

The available data speak in favour of space and time inhomogeneity of gaseous corona of our Galaxy. The observedCIV and SiIV ions are formed mainly by fast photons and localized inHII-clouds of the galactic halo. On the other hand, theNV ions are thermally ionized and localized in the gas corresponding to a transformation of hot intercloud coronal gas in theHII-clouds. TheHII-clouds exhibit downward the gas flow. The galactic fountain can eject the interstellar matter up to height of 1 kpc. Such ejections may be also displayed inCIV, SiIV, and partiallyNV, and partiallyNV absorptions. But large gaseous corona extending up to 3–5 kpc proves to be mass-unbalanced. It is possible that the existence of corona is evidence for violent star formation in the galactic disc in the recent past.