Scientists have discovered the first direct measurements of the chemical and physical properties of a carbon-rich disk surrounding an exoplanet hundreds of light years away that could reveal how moons and planets are formed in our universe. A study published in Science last month by Gabriele Cugno and Sierra L. Grant — hailing from the Department of Astrophysics at the University of Zürich and the Earth and Planets Laboratory at Carnegie Institution, respectively — has revealed that the disk contains carbon-based molecules such as acetylene, benzene, carbon dioxide, ethane, hydrogen cyanide, diacetylene, and propyne in contrast to the disk around its star that contains water but no traces of carbon. The exoplanet, CT Cha b, orbits 46 billion miles from the T Tauri star, CT Cha A, about 625 light years away from Earth. These observations, which have been captured using the James Webb Telescope, may prove to be a significant breakthrough in determining the formation of many celestial bodies.
CT Cha A is a relatively young star at 2 million years old, which is giving scientists an opportunity to discover through the formation of the CT Cha solar system how these planets and moons come to be. Already, the planet CT Cha b has been observed to be continuously growing by using the resources found in its circumplanetary disk as the planet itself is still forming. The carbon found in the disk was determined by making use of the Webb’s MIRI (Mid-Infrared Instrument) medium resolution spectrograph to make infrared observations on its molecular structure, which proved difficult to do because of the glare of the host star on the faint signal of the planet that required disentangling the light of the star from the planet using high contrast techniques. Yet while the disk of CT Cha b contained a multitude of carbon-based molecules, its star’s interestingly didn’t at all.
Cugno and Grant noted that “this difference in disk chemistry between the host disk and its companion indicates rapid, divergent chemical evolution on ∼million-year timescales,” which has enabled several ideas as to how our Solar System was formed. Consisting of 8 planets and more than 400 moons that orbit 6 of them, the formation of these bodies has caught the eyes of these researchers in the wake of these new discoveries. “We want to learn more about how our Solar System formed moons. This means that we need to look at other systems that are still under construction. We’re trying to understand how it all works,” Cugno said, ”how do these moons come to be? What are the ingredients? What physical processes are at play, and over what timescales? Webb allows us to witness the drama of moon formation and investigate these questions observationally for the first time.”
In the coming year, the team plans to launch a comprehensive study surveying the nine disks already available to observe by using the James Webb telescope in order to better understand the diversity of the physical and chemical properties of these disks around young planets. This will further investigate how moons and planets form as well as clear out current uncertainty the team has in how accurate their thoughts about the importance of the difference in carbon content is to celestial creation, as they note how “the carbon content could also be because there’s low dust opacity and the JWST is seeing deeper into the disk where more carbon resides.” Until then, we can only stay on the edge of our seats as we ponder how accurate these studies are in revealing the origins of solar systems and our universe.
