  HR 8799 is a multi-planet system detected in direct imaging, with three
companions known so far. Here, we present spatially resolved VLT/NACO
3.88--4.10 micron spectroscopy of the middle planet, HR 8799 c, which has an
estimated mass of ~10 Mjup, temperature of ~1100 K and projected separation of
38 AU. The spectrum shows some differences in the continuum from existing
theoretical models, particularly longwards of 4 microns, implying that detailed
cloud structure or non-equilibrium conditions may play an important role in the
physics of young exoplanetary atmospheres.
