Scientists have for the first time observed a moon-forming disk around an exoplanet located 400 light-years away from Earth.
A research team led by Myriam Benisty, an astronomer at the University of Grenoble and the University of Chile, has discovered a moon-forming disk surrounding a planet outside our Solar System (an exoplanet). This material disk is about 500 times larger than Saturn’s rings and encircles PDS 70c, a Jupiter-like planet. Scientists have long suspected the existence of such moon-forming disks, but clear images had not been captured until now.
The PDS 70 star system with the host star PDS 70 in the center and the planet PDS 70c (small dot on the right). (Image: ALMA/Benisty et al).
“Our work presents the discovery of a material disk from which natural satellites form,” Benisty stated. The new study was published in The Astrophysical Journal Letters on July 22.
PDS 70c and PDS 70b are two giant gas planets located approximately 400 light-years from Earth. They are still in the early stages of formation, providing a unique opportunity to study young planets and moons.
“So far, scientists have discovered over 4,000 exoplanets, but all belong to mature planetary systems. PDS 70b and PDS 70c remind us of the Jupiter-Saturn pair. They are two of the rare exoplanets discovered that are still in the process of formation,” said Miriam Keppler, a co-author of the study and an expert at the Max Planck Institute for Astronomy.
Using the ALMA telescope system in Chile, the team measured the diameter of the moon-forming disk to be roughly equivalent to the distance between Earth and the Sun (about 150 million km). They also found that the disk contains enough material to create three moons the size of Earth’s Moon. Unlike PDS 70c, PDS 70b does not have such a material disk.
Scientists have hypothesized that planets form within dust disks surrounding young stars, accumulating material as they move along their orbits. During development, a planet can create its own material disk. This disk continues to supply gas and cosmic dust to the young planet. Within the disk, dust particles and gas can also collide, forming increasingly larger celestial bodies that eventually become moons. However, astronomers do not yet fully understand or have observed this process. The new images of PDS 70b and PDS 70c will provide valuable insights.
The research team hopes to observe PDS 70b and PDS 70c again using the Extremely Large Telescope (ELT) being constructed at the Atacama Desert in Chile.
“The ELT will play a crucial role in this research. With much higher resolution, we can map the planetary system in detail,” shared Richard Teague, a co-author of the study and an expert at the Harvard-Smithsonian Center for Astrophysics.
