  Active comets have been detected in several exoplanetary systems, although so
far only indirectly, when the dust or gas in the extended coma has transited in
front of the stellar disk. The large optical surface and relatively high
temperature of an active cometary coma also makes it suitable to study with
direct imaging, but the angular separation is generally too small to be
reachable with present-day facilities. However, future imaging facilities with
the ability to detect terrestrial planets in the habitable zones of nearby
systems will also be sensitive to exocomets in such systems. Here we examine
several aspects of exocomet imaging, particularly in the context of the Large
Interferometer for Exoplanets (LIFE), which is a proposed space mission for
infrared imaging and spectroscopy through nulling interferometry. We study what
capabilities LIFE would have for acquiring imaging and spectroscopy of
exocomets, based on simulations of the LIFE performance as well as statistical
properties of exocomets that have recently been deduced from transit surveys.
We find that for systems with extreme cometary activities such as beta
Pictoris, sufficiently bright comets may be so abundant that they overcrowd the
LIFE inner field of view. More nearby and moderately active systems such as
epsilon Eridani or Fomalhaut may turn out to be optimal targets. If the
exocomets have strong silicate emission features, such as in comet Hale-Bopp,
it may become possible to study the mineralogy of individual exocometary
bodies. We also discuss the possibility of exocomets as false positives for
planets, with recent deep imaging of alpha Centauri as one hypothetical
example. Such contaminants could be common, primarily among young debris disk
stars, but should be rare among the main sequence population. We discuss
strategies to mitigate the risk of any such false positives.
