The observation of a planet forming from stellar material, gas and dust surrounding its parent star, has eluded astronomers for decades. Now, in research published in the latest edition of journal Astronomy and Astrophysics, two teams document the discovery of a forming exoplanet finding the process may be more complicated than previously believed.
In what marks the first observation of this nature, a team of astronomers from the Max Planck Institute in Germany, led by Miriam Keppler, have captured an image of what they believe to be a planet forming from gas and dust. The team has been surveying young stars for signs of planets forming in their surrounding stellar material since 2015 with a piece of imaging equipment specially designed to spot exoplanets, called SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) a part of European Southern Observatory’s Very Large Telescope (VLT) in Chile. One such star, PDS 70, has yielded such an observation.
Examing data collected in 2015 on PDS 70, a 10 million-year-old dwarf star that lies roughly 370 light years from our Sun, Keppler’s team observed a bright point of light and a gap in stellar gas and dust close to the star. There have been some suspected detections of forming exoplanets before, but the observations made by Keppler’s team outshine them considerably. The forming exoplanet, named PDS 70b, is not just extremely bright, but it has also cleared a path for itself in the surrounding material from which it formed making it more visible.
The difficulty in spotting forming exoplanets before has been distinguishing them from their surrounding material. The team countered the possibility of error by viewing the exoplanet in various different wavelengths of light, in which it remained visible. The team’s findings were published in the latest edition of Astronomy and Astrophysics alongside further research conducted by a separate team of astronomers also concerning exoplanet PDS 70b.
This second team, led by Andre Muller a team-mate of Keppler’s at the Max Planck Institute, estimated the mass, size, temperature and orbit of PDS 70b. They found it to be several times the size of Jupiter, with an orbit of approximately 120 years. Its cloudy atmosphere has a temperature of 1000°C. These characteristics are exceptional, considering PDS 70b’s orbit is extremely close to its parent star.
The discovery could change everything we understand about the formation of exoplanets, as the team has included as a model of PDS 70b, a disc of material surrounding the planet gradually falling to its surface in a process known as accretion. The accreting material helps explain the exceptionally high temperature of PDS 70b. This facet of the formation of PDS 70b seems to contradict previous models of exoplanet formation.
Keppler and her team will continue to observe PDS 70b with SPHERE but also hopes to make observations with the Atacama Large Millimeter/submillimeter Array, a collection of radio dishes also located in Chile. The array has the added ability to observe dust and gas which should enable the confirmation of the circumplanetery disc of material accreting to the planet.