The First H-band Spectrum of the Massive Gas Giant Planet beta Pictoris b with the Gemini Planet Imager

TL;DR

This paper presents the first H-band spectrum of the exoplanet beta Pictoris b obtained with the Gemini Planet Imager, revealing its atmospheric properties and confirming its planetary nature.

Contribution

First H-band spectrum of beta Pictoris b obtained with GPI, providing new insights into its atmospheric characteristics and confirming its planetary status.

Findings

Effective temperature of 1650 ± 50 K

Surface gravity log(g) = 4.0 ± 0.25

Mass estimated between 10-12 Jupiter masses

Abstract

Using the recently installed Gemini Planet Imager (GPI), we have taken the first H-band spectrum of the planetary companion to the nearby young star beta 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 microns). The spectrum has a resolving power of $\sim$ 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 $1650 \pm 50$ K and a surface gravity of $\log(g) = 4.0 \pm 0.25$ (cgs units). These values agree well with predictions from planetary evolution models for a gas giant with mass between 10 and 12 $M_{\rm Jup}$ and age between 10 and 20 Myrs.