Astronomers using the NASA / ESA / CSA James Webb space telescope found the carbon-rich disc surrounding CT Cha B, a giant exoplanet about 620 light years from the earth in the Constellation de Chamaeleon. Their results provide the first direct overview of the chemical and physical properties of the material accredited on a gas giant and in its potential moon system.
An artistic rendering of a disc of dust and gas surrounding the young exoplanet ct cha b. Image credit: NASA / ESA / CSA / STSCI / G. CUGNON, University of Zurich & NCCR Planets / S. Grant, Carnegie Institution for Science / J. Olmsted, STSCI / L. Hustak, STSCI.
CT CHA, also known as PDS 44 and ICT 454259409, has only 2 million years and is still accumulated by circumsallary equipment.
However, the circumstories discovered by WebB is not part of the largest accretion disc around the central star.
“We can see evidence of the disc around the companion, and we can study chemistry for the first time,” said Dr. Sierra Grant, astronomer of the institution for science.
“We are not only attended by the formation of the Moon – we are also witnessing the formation of this planet.”
“We see what material accrete to build the planet and the moons,” added Dr. Gabriele Cugno, astronomer at the University of Zurich and the National Center of Compence in Research Planets.
CT Cha B infrared observations were made with the webb miri (median infrared instrument) using its average resolution spectrograph.
A first overview of webb archive data revealed signs of molecules in the circumstories disc, which motivated a deeper dive into the data.
Because the low signal of the planet is buried in the glare of the host star, astronomers had to disentangle the light of the planet’s star using high contrast methods.
“We saw molecules on the location of the planet, so we knew that there were stuff there that were worth digging and spending a year trying to tease the data. It really took a lot of perseverance,” said Dr. Grant.
In the end, the researchers discovered seven carbon molecules in the planet’s disc, including acetylene (C2H2) and benzene (c6H6).
This carbon rich chemistry contrasts strongly with the chemistry observed in the disc around the host star, where the researchers found water but not carbon.
The difference between the two discs offers evidence of their rapid chemical evolution over only 2 million years.
“We want to know more about how our solar system has formed moons.
“How are these moons becoming?” What are the ingredients? What physical processes are at stake, and on what deadlines? ”
“Webb allows us to attend the drama of the formation of the moon and to investigate these questions observedly for the first time.”
The results were published today in the Astrophysical newspaper letters.
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Gabriele CUGNO & SIERRA L. Grant. 2025. A disc rich in carbon surrounding a planetary mass companion. Apjl 991, L46; DOI: 10.3847 / 2041-8213 / AE0290
