Spatially Resolved Spectroscopy of the Exoplanet HR 8799 c

HR 8799 is a multi-planet system detected in direct imaging, with three companions known so far. Here, we present spatially resolved Very Large Telescope/NACO 3.88-4.10 μm spectroscopy of the middle planet, HR 8799 c, which has an estimated mass of ~10 M _Jup, 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 μm, implying that detailed cloud structure or non-equilibrium conditions may play an important role in the physics of young exoplanetary atmospheres.

Based on observations collected at the European Southern Observatory, Chile (ESO No. 084.C-0072) and at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.