Planets form from large disks of gas and dust surrounding stars, and thanks to the European Southern Observatory's (ESO) Very Large Telescope (VLT), we are now learning a lot more about the growing pains of young planetary systems.
ESO’s new instrument, called SPHERE, was capable of observing how three systems evolved over time, with one of them actually seen changing in real time. The researchers have seen how planets can sculpt their protoplanetary disks in a variety of ways. They can form gaps, rings, and even spiral arms.
We don’t know enough about planetary formation to work out what is the link between the properties of the planets and the shape of the disks, but instruments like SPHERE are helping scientists to get a better understanding of it. Three papers, discussing each system, were accepted for publication in the journal Astronomy & Astrophysics.
HD 135344B has a spiral structure due to large exoplanets forming. ESO/T. Stolker et al.
Protoplanetary disks tend to mostly have spiral structures, like HD 135344B, observed in a paper in this campaign by Tomas Stolker of the Anton Pannekoek Institute for Astronomy, the Netherlands. The star is about 450 light-years away, and its disk shows two large arms created by one or multiple massive protoplanets.
Astronomers also saw four dark streaks crossing the disk, due to turbulent movements of material. One of these four streaks remarkably changed over months of observations. This real-time change tells astronomers that there are effects happening at smaller scales that we can see, and they might play an important role.
The other two protoplanetary disks have instead concentric rings. RX J1615, 600 light-years from Earth, was observed by Jos de Boer, of Leiden Observatory. The system has been compared to a scaled-up version of Saturn’s rings, and it is incredibly young, about 1.8 million years old according to the study. The rings could be generated by planets that are still not formed yet.
Disc around the young star RX J1615. ESO/ J. de Boer et al.
A similar structure is seen in HD 97048, a young star 500 light-years from us. In a paper written by a team led by Christian Ginski, also of Leiden Observatory, the researchers describe how the disk reveals four gaps with planets smaller than Jupiter as the possible cause.
Many researchers plan to investigate more systems like these. To truly work out what’s going on, we need a more sizeable body of work from current instruments and deeper observations from new instruments like the James Webb Space Telescope.