A deep H I survey with the VLA of the spiral galaxy NGC 2403 has revealed the existence of a thick, low density layer of neutral gas surrounding the thin 'cold' disk. This layer has a mean rotation velocity 25-50 km s(-1) lower than that of the disk and a 10-20 km s(-1) inflow towards the centre of the galaxy. In the central parts there are velocity differences from rotation of up to 150 km s(-1). Chandra observations of NGC 2403 show a diffuse, hot X-ray emitting gas component with a temperature of a few 106 K. These results point at galactic fountain type of flows between disk and halo. 'Halo' gas with similar characteristics has also been observed in other spiral galaxies (e.g. NGC 6946, NGC 891). Such gas is probably similar to the IVCs and to some of the HVCs of the Milky Way.
|Tijdschrift||Astrophysics and Space Science|
|Nummer van het tijdschrift||3-4|
|Status||Published - jan-2004|