Astronomers used an instrument called SPHERE, an exoplanet hunter capable of detecting planets and disks surrounding stars, which was partially assembled and designed in France and in Grenoble at the Grenoble Institute of Planetology and Astrophysics (UGA/CNRS). This instrument is designed to correct for turbulence in Earth’s atmosphere in order to provide the sharpest possible images and take full advantage of the power of the 8-meter VLT telescope located in the Atacama Desert. Using SPHERE’s advanced imaging and polarimetry capabilities, researchers analyzed images of 161 young stars located in the vicinity of our Sun.

The study revealed detailed images of 51 debris disks, four of which were photographed for the first time (Figure 1). These images reveal the fine dust contained within these disks, as small dust particles are very abundant in them. This dust is produced during collisions between larger bodies—such as asteroids and comets—and thus effectively scatters the light from their star. This dust is distributed in the form of rings around the star, and depending on the viewing angle from Earth, the rings can be observed from above or from the side, resulting in different geometries, as shown in Figure 1.


 
SPHERE observations show that many planetary systems share a structure similar to our own, with several planets orbiting within dust rings similar to the Kuiper Belt. Among them, HR 8799 stands out as the first system in which four gas giant planets located between two debris belts were directly imaged with the VLT—a historic discovery in 2008. In our solar system, four gas or ice giants also orbit between the asteroid belt and the Kuiper belt. In this new study, the SPHERE image of this famous planetary system reveals the innermost dust ring for the first time. The team of astronomers also reports the discovery of a second transiting giant planet in another system, HD 114082. Both planets orbit close to their star and lie within an analog of the Kuiper Belt, thus providing a new case study of the interaction between planets and a debris disk.

Their gravitational interactions can shape the distribution of dust particles, producing a variety of structures—such as asymmetries or regions of increased density—that reveal the presence of planets otherwise invisible in these observations. In several systems, these observations provide strong evidence of the interaction between planets and disks. To illustrate this, Figure 2 shows detailed SPHERE images of the debris disks around the young stars HD 106906 and HR 4796. The disk around HD 106906 exhibits a left-right asymmetry in brightness and hosts a giant planet, whose gravitational influence is likely responsible for this asymmetry. The disk around HR 4796, on the other hand, has very sharp edges—a characteristic sign of dynamic shaping by planets orbiting inside the ring, much like Neptune does with the Kuiper Belt. 

Future observations using the JWST space telescope and ESO’s future giant ELT telescope will allow astronomers to directly detect the planets that create these structures and to study fainter or more compact disks, thereby providing an unprecedented view of the formation and evolution of these planetary systems.