NASA\u2019s James Webb Space Telescope has provided the first direct measurements of the chemical and physical properties of a potential moon-forming disk encircling a large exoplanet. The carbon-rich disk surrounding the world called CT Cha b, which is located 625 light-years away from Earth, is a possible construction yard for moons, although no moons are detected in the Webb data.<\/p>\n
The results published today in The Astrophysical Journal Letters<\/a>.<\/p>\n The young star the planet orbits is only 2 million years old and still accreting circumstellar material. However, the circumplanetary disk discovered by Webb is not part of the larger accretion disk around the central star. The two objects are 46 billion miles apart.<\/p>\n Observing planet and moon formation is fundamental to understanding the evolution of planetary systems across our galaxy. Moons likely outnumber planets, and some might be habitats for life as we know it. But we are only now entering an era where we can witness their formation.<\/p>\n This discovery fosters a better understanding of planet and moon formation, say researchers. Webb\u2019s data is invaluable for making comparisons to our solar system’s birth over 4 billion years ago.<\/p>\n \u201cWe can see evidence of the disk around the companion, and we can study the chemistry for the first time. We’re not just witnessing moon formation \u2014 we’re also witnessing this planet\u2019s formation,\u201d said co-lead author Sierra Grant of the Carnegie Institution for Science in Washington.<\/p>\n \u201cWe are seeing what material is accreting to build the planet and moons,\u201d added main lead author Gabriele Cugno of the University of Z\u00fcrich and member of the National Center of Competence in Research PlanetS.<\/p>\n Infrared observations of CT Cha b were made with Webb\u2019s MIRI (Mid-Infrared Instrument) using its medium resolution spectrograph. An initial look into Webb\u2019s archival data revealed signs of molecules within the circumplanetary disk, which motivated a deeper dive into the data. Because the planet\u2019s faint signal is buried in the glare of the host star, the researchers had to disentangle the light of the star from the planet using high-contrast methods.<\/p>\n \u201cWe saw molecules at the location of the planet, and so we knew that there was stuff in there worth digging for and spending a year trying to tease out of the data. It really took a lot of perseverance,\u201d said Grant.<\/p>\n Ultimately, the team discovered seven carbon-bearing molecules within the planet\u2019s disk, including acetylene (C2H2) and benzene (C6H6). This carbon-rich chemistry is in stark contrast to the chemistry seen in the disk around the host star, where the researchers found water but no carbon. The difference between the two disks offers evidence for their rapid chemical evolution over only than 2 million years.<\/p>\n A circumplanetary disk has long been hypothesized as the birthplace of Jupiter\u2019s four major moons. These Galilean satellites must have condensed out of such a flattened disk billions of years ago, as evident in their co-planar orbits about Jupiter. The two outermost Galilean moons, Ganymede and Callisto, are 50% water ice. But they presumably have rocky cores, perhaps either of carbon or silicon.<\/p>\n \u201cWe 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\u2019re trying to understand how it all works,\u201d said Cugno. \u201cHow do these moons come to be? What are their 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.\u201d<\/p>\n In the coming year, the team will use Webb to perform a comprehensive survey<\/a> of similar objects, to better understand the diversity of physical and chemical properties in the disks around young planets.<\/p>\n The James Webb Space Telescope is the world\u2019s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing 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).<\/p>\n To learn more about Webb, visit:<\/p>\n https:\/\/science.nasa.gov\/webb<\/a><\/p>\n Read more: NASA\u2019s Webb Finds Planet-Forming Disks Lived Longer in Early Universe<\/a><\/p>\n Explore more: ViewSpace Detecting Other Worlds: Direct Imaging<\/a><\/p>\n Explore more: How to Study Exoplanets: Webb and Challenges<\/a><\/p>\n Read more: Webb\u2019s Star Formation Discoveries<\/a><\/p>\n More Webb News<\/a><\/p>\n More Webb Images<\/a><\/p>\n Webb Science Themes<\/a><\/p>\n Webb Mission Page<\/a> <\/p>\n