THE FIRST H -BAND SPECTRUM OF THE GIANT PLANET β PICTORIS b

This is the authors' abstract. We don't add key points for this paper.

Using the recently installed Gemini Planet Imager (GPI), we have obtained the first H -band spectrum of the planetary companion to the nearby young star β Pictoris. GPI is designed to image and provide low-resolution spectra of Jupiter-sized, self-luminous planetary companions around young nearby stars. These observations were taken covering the H band (1.65 μm). The spectrum has a resolving power of ∼45 and demonstrates the distinctive triangular shape of a cool substellar object with low surface gravity. Using atmospheric models, we find an effective temperature of 1600–1700 K and a surface gravity of log ( g ) = 3.5–4.5 (cgs units). These values agree well with "hot-start" predictions from planetary evolution models for a gas giant with mass between 10 and 12 M Jup and age between 10 and 20 Myr.