Erosion processes also exist in the cosmos, a study shows: Astronomers have used data from the Webb Telescope to document how the radiation wind from nearby star giants erodes the protoplanetary disk of a young star in the Orion Nebula. According to the calculations, at the rate of erosion found, all gaseous material could have blown away in just about a million years. This greatly limits the likelihood of gas planets forming in the system, say the researchers.
What happens in the early evolutionary history of stars and their planetary systems? When asking this question, astronomers look at the stellar nurseries of the cosmos: There are certain regions that are characterized by dense accumulations of matter in which a particularly large number of new stars and planetary systems are forming. In these star clusters there are examples of the category of our sun, but also heavyweights with often ten times more mass and 100,000 times more intense luminosity. It is obvious that interactions between the different stars can occur in the relatively densely populated star clusters.
Externally irradiated star systems
Theoretical models predict that the intense radiation from massive stars can influence the planet-forming disks of material from smaller neighbors. A mechanism called photodissociation is responsible for this: The radiation from a massive neighboring star heats gases in the protoplanetary disk, causing them to be mobilized and ultimately able to escape from the system. As the astronomers led by Olivier Berné from the University of Toulouse now report, they have now succeeded in directly observing this effect for the first time.
Their focus was on a young star with a protoplanetary disk located in the Orion Nebula. This is a star-forming region about 1,400 light-years away from us, which is visible in the area of the “sword” of the famous constellation. In addition to the ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope in Chile, the James Webb Space Telescope (JWST) was used in the study. Its high sensitivity in the infrared wavelength range also allows you to see through obscuring dust clouds. Since 2022, the JWST has been able to clarify the image of the Orion Nebula enormously and show new celestial bodies and their structures within them. This is also the case with the young star and its protoplanetary disk called d203-506.
On the trail of the effects of radiation wind
As the researchers report, the system, which is only around a million years old, is being irradiated laterally by a nearby cluster of massive stars. According to them, the impact of this can now be seen in the data from ALMA and the JWST. As they explain, the effects of photoevaporation of gases in the disk of matter became clear from spectroscopic analyzes of the emitted light from the protoplanetary disk. The data reflected how matter is mobilized by the effect of light. This means that at d203-506 structures and processes emerged that were caused by the radiation wind from the neighboring star cluster.
The researchers were also able to document how the irradiation drives the gas from the protoplanetary disk into space. Based on the data, it was also possible to quantify the corresponding loss rate. As the team reports, the results showed that at the current rate of decline, the gas could have disappeared from the disk in less than a million years. As the astronomers explain, this significantly limits the likelihood that gas planets can form in the young system.
The results now document how intensively radiation can affect cosmic matter structures and how decisively massive stars can shape the formation of their neighbors' planetary systems. Finally, the authors emphasize that such processes may also have played a role in the history of our own cosmic home: “Studies into the formation of the solar system suggest that it also originally formed in a star cluster that contained one or more massive stars . “It is possible that the development of the solar system was also influenced by external radiation,” said Berné and his colleagues.