L-band Integral Field Spectroscopy of the HR 8799 Planetary System

Understanding the physical processes sculpting appearance of young gas-giant planets is complicated by degeneracies confounding effective temperature, surface gravity, cloudiness, and chemistry. To enable more detailed studies, spectroscopic observations covering a wide range wavelengths required. Here we present first L-band HR 8799 d e low-resolution bandwidth measurements c. These were facilitated an upgraded LMIRCam/ALES instrument at LBT, together with new apodizing phase plate coronagraph. Our data are generally consistent previous photometric similar wavelengths, yet there exists some tension narrowband photometry for With addition our spectra, each three innermost observed in system have had their spectral energy distributions measured integral field spectroscopy $\sim0.9$ to $4.1~\mu\mathrm{m}$. We combine these spectra from literature fit synthetic model atmospheres. demonstrate that bolometric luminosity not sensitive choice atmosphere used interpolate between extrapolate beyond them. Combining age mass constraints, show predictions evolutionary models narrowly peaked planetary radius. By holding parameters predicted values, flexible cloud can provide good fits while being expectations models.