Far-infrared excess emission as a tracer of disk-halo interaction
  Given the current and past star-formation in the Milky Way in combination
with the limited gas supply, the re-fuelling of the reservoir of cool gas is an
important aspect of Galactic astrophysics. The infall of \ion{H}{i} halo clouds
can, among other mechanisms, contribute to solving this problem. We study the
intermediate-velocity cloud IVC135+54 and its spatially associated
high-velocity counterpart to look for signs of a past or ongoing interaction.
Using the Effelsberg-Bonn \ion{H}{i} Survey data, we investigated the interplay
of gas at different velocities. In combination with far-infrared Planck and
IRIS data, we extended this study to interstellar dust and used the correlation
of the data sets to infer information on the dark gas. The velocity structure
indicates a strong compression and deceleration of the infalling high-velocity
cloud (HVC), associated with far-infrared excess emission in the
intermediate-velocity cloud. This excess emission traces molecular hydrogen,
confirming that IVC135+54 is one of the very few molecular halo clouds. The
high dust emissivity of IVC135+54 with respect to the local gas implies that it
consists of disk material and does not, unlike the HVC, have an extragalactic
origin. Based on the velocity structure of the HVC and the dust content of the
IVC, a physical connection between them appears to be the logical conclusion.
Since this is not compatible with the distance difference between the two
objects, we conclude that this particular HVC might be much closer to us than
complex C. Alternatively, the indicators for an interaction are misleading and
have another origin.
