A new planet is born

This Picture of the Week shows a newly-formed planet with a mass similar to Jupiter’s orbiting the star HD 169142. The star has a disc around it, and as the protoplanet moves it carves a circular gap in the disc, as seen in the first image. But how was this planet found?

Astronomers observed the system over several years with the SPHERE instrument at ESO’s Very Large Telescope in Chile. A new re-analysis of this data, led by Iain Hammond from Monash University in Australia, confirmed the presence of this protoplanet, which moves around the star at a distance somewhat larger than that between Neptune and the Sun. They also identified a spiral wake that the protoplanet leaves behind as it rearranges part of the material in the disc, much like a boat can create a wake as it moves through water.

A protoplanet forms during the early stages of a planetary system. It grows as it accretes dust, gas, rocks and other materials that surround its host star, clearing its orbit and creating gaps like the one seen here. The SPHERE instrument is specifically designed to observe these features, blocking light from the star to increase the contrast in the image, and correcting the blur caused by atmospheric turbulence to improve the resolution. By studying the spiral wake and the gap that the protoplanet has created around the star HD 169142, astronomers can learn more about how giant planets such as Jupiter form.

Link

• Video version of this image.