Webb Telescope: Discovering an unusual environment for planet formation

Astronomers from eleven European countries are conducting research on the project mind Using the mid-range infrared (MIRI) instrument on board JWST Conditions in the interior of protoplanetary disks around young stars. 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.

For this reason, researchers… Aditya Arabhavi Researchers from the University of Groningen examined the chemical composition of the disk of dust and gas around ISO-Chal 147, a 0.11 solar mass star, in the Chameleon I star-forming region using MIRI. Astrophysicist Manuel Goodale from the University of Vienna, played a leading role in developing this JWST instrument, as well as one that has just been published in the journal Science. analysis.

Mysterious mechanism

“We are amazed by the many hydrocarbons present in the protoplanetary disk. In total, we identified 13 different carbon-containing molecules in the gas, including ethane, ethylene, propylene and benzene. This is the richest production of hydrocarbons 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 relies heavily on carbon, not on oxygen,” says Godel. “The question is why and what is happening here?” So the researchers are looking for a mechanism by which oxygen is suppressed and carbon is increased.

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) – slow down in the gas disk and thus migrate 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 lots of carbon,” says the astrophysicist.

“Strange” atmosphere.

However, planets are more likely to form in such an environment “which could have an exotic atmosphere,” says Godel. 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 common.” 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.