The planet GU Psc b and its star GU Psc composed of visible and infrared images from the Gemini South Observatory and an infrared image from the CFHT. Because infrared light is invisible to the naked eye, astronomers use a colour code in which infrared light is represented by the colour red. GU Psc b is brighter in infrared than in other filters, which is why it appears red in this image.
A gas giant has been added to the short list of exoplanets discovered through direct imaging. It is located around GU Psc, a star three times less massive than the Sun and located in the constellation Pisces. The international research team, led by Marie-Ève Naud, a PhD student in the Department of Physics at the Université de Montréal, was able to find this planet by combining observations from the Observatoire Mont-Mégantic (OMM), the Canada-France-Hawaii Telescope (CFHT), the W.M. Keck Observatory, and the Gemini North and South Observatories.
Observing a planet does not directly allow determining its mass. Instead, researchers use theoretical models of planetary evolution to determine its characteristics. The spectrum of GU Psc b obtained from the Gemini North Observatory on Maunakea was compared to such models to show that it has a temperature of around 800°C. Knowing the age of GU Psc due to its location in AB Doradus, the team was able to determine its mass, which is 9-13 times that of Jupiter.
The team has started a project to observe several hundred stars and detect planets lighter than GU Psc b with similar orbits. The discovery of GU Psc, a rare object indeed, raises awareness of the significant distance that can exist between planets and their stars, opening the possibility of searching for planets with powerful infrared cameras using much smaller telescopes such at the one at the Observatoire du Mont-Mégantic. The researchers also hope to learn more about the abundance of such objects in the next few years, in particular, using GPI instruments on Gemini, CFHT's upcoming instrument SPIRou, and the James Webb Space Telescope's FGS/NIRISS.