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Today it is known that planets form from vast discs of gas and dust encircling newborn stars, known as protoplanetary discs. These can extend for thousands of millions of kilometres. Over time, the particles in these protoplanetary discs collide, combine and eventually build up into planet-sized bodies. However, the finer details of the evolution of these planet-forming discs remain mysterious.
Credit: ESO
SPHERE is a recent addition to the VLT’s array of instruments and with its combination of novel technologies, it provides a powerful method to directly image the fine details of protoplanetary discs. The interaction between protoplanetary discs and growing planets can shape the discs into various forms: vast rings, spiral arms or shadowed voids. These are of special interest as an unambiguous link between these structures and the sculpting planets is yet to be found; a mystery astronomers are keen to solve. Fortunately, SPHERE’s specialised capabilities make it possible for research teams to observe these striking features of protoplanetary discs directly.
For example, RX J1615 is a young star, which lies in the constellation of Scorpius, 600 light-years from Earth. A team led by the Jos de Boer, of Leiden Observatory in the Netherlands, found a complex system of concentric rings surrounding the young star, forming a shape resembling a titanic version of the rings that encircle Saturn. Such an intricate sculpting of rings in a protoplanetary disc has only been imaged a handful of times before, and even more excitingly, the entire system seems to be only 1.8 million years old. The disc shows hints of being shaped by planets still in the process of formation.
Using the ESO’s SPHERE instrument at the Very Large Telescope, a team of astronomer observed the planetary disc surrounding the star RX J1615 which lies in the constellation of Scorpius, 600 light-years from Earth. The observations show a complex system of concentric rings surrounding the young star, forming a shape resembling a titanic version of the rings that encircle Saturn. Such an intricate sculpting of rings in a protoplanetary disc has only been imaged a handful of times before. The central part of the image appears dark because SPHERE blocks out the light from the brilliant central star to reveal the much fainter structures surrounding it.
Credit: ESO, J. de Boer et al.
Using the ESO’s SPHERE instrument at the Very Large Telescope, a team of astronomer observed the planetary disc surrounding the star HD 135344B, about 450 light-years away. The disc shows prominent spiral arm-like structures. These are thought to have been created by one or multiple massive protoplanets, destined to become Jupiter-like worlds.The central part of the image appears dark because SPHERE blocks out the light from the brilliant central star to reveal the much fainter structures surrounding it.
Credit: ESO, T. Stolker et al.
As with the concentric rings found by de Boer and Ginski, these observations by Stolker’s team prove that the complex and changing environment of the discs surrounding young stars are still capable of producing surprising new discoveries. By building an impressive body of knowledge about these protoplanetary discs, these teams are stepping closer to understanding how planets shape the discs that form them — and therefore understanding planet formation itself.
Contacts and sources:
Tomas Stolker, Anton Pannekoek Institute for Astronomy
Christian Ginski, Leiden University
Richard Hook, ESO
Related links;
Research paper by Jos de Boer et al.
Research paper by Christian Ginski et al.
Research paper by Tomas Stolker et al.