Gemini Confirms a Free-Floating Planet

Our observed spectrum of PSO J318.5−22 (black) compared to the forward model with our best fit parameters (red). The median residual of the fit is 0.079 (in normalized F_λ units), which is larger than the median uncertainty (0.048) of our observed spectrum. The rms of the residuals (0.12) indicates systematic uncertainties of ≈10%.

Gemini observations confirm the identity of an extremely red object as a planet. This is a free-floating member of the Beta Pictoris moving group. Spectral confirmation of the object’s group membership verifies the age, and therefore the mass estimate is more secure, at 8.3 ± 0.5 times the mass of Jupiter. K. Allers of Bucknell University led the work, which was based on observations using the Gemini Near-InfraRed Spectrograph (GNIRS) on the Gemini North telescope in a Director’s Discretionary time program. More information about this work is available at the Gemini webpage, and full results will appear in The Astrophysical Journal. A preprint is available now.