An international team of astronomers used NASA’s James Webb Space Telescope to study the disk of gas and dust around a young, very low-mass star. The results reveal the largest number of carbon-containing molecules ever observed in such a disk. These findings have implications for the possible composition of any planets that may form around this star.

NASA’s James Webb Space Telescope

The James Webb Space Telescope is the world’s leading space science observatory. Webb solves mysteries in our solar system, looks beyond to distant worlds around other stars, and explores the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners ESA (European Space Agency) and CSA (Canadian Space Agency).

What Webb found

Rocky planets are more likely than gas giants to form around low-mass stars, making them the most common planets around our galaxy’s best-known stars. Little is known about the chemistry of such planets, which can be either similar to or very different from Earth. By studying the disks from which such planets form, astronomers hope to better understand the planet-forming process and the compositions of the resulting planets.

Planet-forming disks around very low-mass stars are difficult to study because they are smaller and fainter than disks around high-mass stars.

“Webb has better sensitivity and spectral resolution than previous infrared space telescopes,” explained lead author Aditya Arabhavi of the University of Groningen in the Netherlands. “These observations are not possible from Earth because the emission from the disk is blocked by our atmosphere.”

Photograph of the star NGC 3324 by the James Webb Space Telescope Source: Nasa

In a new study, this team explored the region around a very low-mass star known as ISO-ChaI 147. It’s a 1- to 2-million-year-old star that weighs just 0.11 times that of the Sun. The spectrum revealed by Webb’s MIRI shows the richest hydrocarbon chemistry yet seen in a protoplanetary disk – a total of 13 different carbon-bearing molecules. The team’s findings include the first detection of ethane (C 2 H 6 ) outside our solar system, as well as ethylene (C 2 H 4 ), propyne (C 3 H 4 ) and the methyl radical CH 3 .

“These molecules have already been detected in our solar system, such as in comets such as 67P/Churyumov–Gerasimenko and C/2014 Q2 (Lovejoy),” Arabhavi added. “Webb allowed us to understand that these hydrocarbon molecules are not just different but abundant. It is amazing that we can now see the dance of these molecules in the planetary cradles. It’s a very different planet-forming environment than what we usually think.”

The team shows that these effects have large implications for the chemistry of the inner disk and the planets that may form there. Since Webb revealed that the gas in the disk is so carbon-rich, there is probably some carbon in the solid materials from which the planets would form. As a result, planets that may form there may eventually be carbon-poor. (Earth itself is considered carbon-poor.)

“This is profoundly different from the composition we see in disks around solar-type stars, which are dominated by oxygen-carrying molecules such as water and carbon dioxide,” added team member Inga Kamp, also from the University of Groningen. “This item proves that this is a unique class of item.”

“It is incredible that we can detect and quantify the amount of molecules we know well on Earth, such as benzene, in an object more than 600 light-years away,” added team member Agnés Perrin of the Center National de la Recherche Scientifique. in France.

This work also highlights the critical need for scientists to collaborate across disciplines. The team notes that these results and accompanying data can contribute to other fields, such as theoretical physics, chemistry and astrochemistry, to interpret spectra and investigate new features in this wavelength range.