1996A&A...312...67K

We present observational evidence in ROSAT all-sky survey data that large parts of the high-velocity cloud (HVC) complex C are associated with soft X-ray radiation. Moreover the new Leiden/Dwingeloo northern-sky survey shows very faint HI 21-cm line emission which connects the HVC velocity regime with the low-velocity atomic hydrogen of the galactic disk by velocity bridges. Finally we find a close positional correlation of soft X-ray enhancements and the atomic hydrogen velocity bridges. Thus we obtain for the first time direct evidence that large parts of the HVC complex C are impacting onto the galactic disk. As a consequence, the HVCs of complex C are closer to the galactic disk than previously assumed. Most probably the gas of the Reynolds and/or Lockman layers are the collision partners of the HVCs.