Tucson Standard

An international team of astronomers, including scientists from the University of Arizona, has made a significant discovery using NASA's James Webb Space Telescope. They studied the disk of gas and dust around a young, low-mass star and found the largest number of carbon-containing molecules ever seen in such a disk. This discovery could have implications for understanding the potential composition of planets that may form around this star.

Rocky planets are more likely to form around low-mass stars than gas giants, making them common in our galaxy. The chemistry of these worlds is not well understood and could be similar to or different from Earth. By examining the disks where these planets form, astronomers aim to gain insight into planet formation processes and their compositions.

The findings were published in Science and build on a 2009 study led by Ilaria Pascucci, a professor at UArizona who also co-authored this new study. In previous research, Pascucci's team used the Spitzer Space Telescope to identify differences in gas composition between disks around very-low mass stars and those around solar-type or higher-mass stars.

"The James Webb spectrum is fantastic," said Pascucci. "With higher resolution and sensitivity than Spitzer, it enabled detection of many carbon-bearing molecules – even complex ones like benzene."

The study reveals that the gas composition is rich in hydrocarbons, expanding scientists' understanding of chemical complexity in disks around very low-mass stars. These exoplanets could develop an early atmosphere rich in hydrocarbons, unlike Earth's early atmosphere.

Disks around very low-mass stars are challenging to study due to their size and faintness compared to those around high-mass stars. The MIRI Mid-INfrared Disk Survey (MINDS) program aims to use Webb's capabilities to connect disk chemical inventories with exoplanet properties.

"Webb has better sensitivity and spectral resolution than previous infrared space telescopes," said lead author Aditya Arabhavi from the University of Groningen. "These observations are not possible from Earth because emissions from the disk are blocked by our atmosphere."

Researchers focused on ISO-ChaI-147, a 1-to-2-million-year-old star weighing just 0.11 times as much as the sun. Webb's Mid-Infrared Instrument revealed 13 different carbon-bearing molecules in its protoplanetary disk, marking the richest hydrocarbon chemistry observed so far outside our solar system.

"These molecules have already been detected in our solar system," Arabhavi explained. "Webb allowed us to understand that these hydrocarbon molecules are not just diverse but also abundant."

The results suggest significant implications for inner disk chemistry and potential planet formation there. With such rich carbon gas present, any resulting planets might be carbon-poor like Earth.

"This is profoundly different from what we see in disks around solar-type stars," noted Inga Kamp from the University of Groningen.

"It's incredible that we can detect...molecules...more than 600 light-years away," said Agnés Perrin from France's Centre National de la Recherche Scientifique.

Next steps involve expanding studies to more such disks around very low-mass stars to assess how common these carbon-rich regions might be.

"The expansion will allow us...to better understand how these molecules can form," stated Thomas Henning from Germany's Max-Planck-Institute for Astronomy.