We present direct imaging observations at wavelengths of 3.3, 3.8 (L′band), and 4.8 (M band) μm, for the planetary system surrounding HR8799. All three planets are detected at L′. The c and d components are detected at 3.3 μm, and upper limits are derived from the M-band observations. These observations provide useful constraints on warm giant planet atmospheres. We discuss the current age constraints on the HR8799 system and show that several potential co-eval objects can be excluded from being co-moving with the star. Comparison of the photometry is made to models for giant planet atmospheres. Models that include non-equilibrium chemistry provide a reasonable match to the colors of c and d. From the observed colors in the thermal infrared, we estimate T eff < 960 K for b and T eff = 1300 and 1170 K for c and d, respectively. This provides an independent check on the effective temperatures and thus masses of the objects from the Marois et al. results.
- Instrumentation: adaptive optics
- Planets and satellites: atmospheres
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science