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The Webb telescope finds a completely different environment for planet formation

The Webb telescope finds a completely different environment for planet formation

An international research team with Austrian participation has discovered a completely different planetary formation environment with the help of the James Webb Space Telescope (JWST). As scientists report in the journal Science, a planet-forming disk around a low-mass star located more than 600 light-years away contains the richest hydrocarbon chemistry ever observed in such a planet-forming region.

In the MINDS project, astronomers from eleven European countries are investigating conditions in the interiors of protoplanetary disks around young stars using the mid-infrared instrument (MIRI) on board the James Webb Space Telescope. These disks consist of gas and dust from which rocky planets can form. In particular, very low-mass stars – less than a third of the mass of our Sun – host more such Earth-like planets in their orbits than other types of stars.

That's why researchers led by Aditya Araphavi from the University of Groningen (Netherlands) examined the chemical composition of the dust and gas disk around ISO-Chal 147, a 0.11 solar mass star, in the Chameleon I star-forming region using MIRI. . Astrophysicist Manuel Gödel of the University of Vienna played a leading role in developing the James Webb Space Telescope instrument, as well as in the current analysis.

A variety of molecules containing carbon

“We are amazed by the large number of hydrocarbons present in the planetary disk. In total, we identified 13 different carbon-containing molecules in the gas, including ethane, ethylene, propylene and benzene,” Godel told APA. This is the richest hydrocarbon production in such a disk, “we have never seen anything like it before.” Ethane was first discovered in a planetary environment outside the solar system.

The composition of the planet-forming region differs fundamentally from the composition of disks orbiting Sun-like stars, that is, more massive stars. While water vapor (H2O) and carbon dioxide (CO2) dominate there, there were no signs of these oxygen-rich molecules in the planet-forming region examined. “There is chemistry that is very much based on carbon and not on oxygen,” Godel said. “The question is why and what is happening here.” Therefore, researchers are looking for a mechanism by which oxygen is suppressed and carbon increases.

One possibility is that oxygen-containing molecules in the disk are rapidly transported from the outside to the inside and eventually dissolve in the star. This could happen, for example, because water and carbon dioxide ice, along with clumped together solids up to a centimeter in size – as the researchers wrote in their paper about “pebbles” (pebbles) – are slowed down in the gas disk and thus move Faster and farther towards the star falling on it. “In this way, water and carbon dioxide can be gradually removed from the disk, leaving behind an oxygen-poor environment with a lot of carbon,” the astrophysicist said.

However, planets are more likely to form in such an environment “which could have an exotic atmosphere,” Goodale says. In our solar system, only Saturn's moon Titan has such an atmosphere, which consists of nitrogen, methane and many hydrocarbons. However, the chemistry in such a hydrocarbon-rich atmosphere is very different, but at the same time “very promising for creating molecules that can lead to life.” Because life as we know it is based on carbon.

According to the astrophysicist, such a completely different, carbon-dominated chemistry “could certainly be widespread.” So the research team wants to examine more protoplanetary disks around low-mass stars in order to better understand how common these exotic carbon-rich regions are where terrestrial planets form.

service: Internet: http://dx.doi.org/10.1126/science.adi8147