ESA | Space Science | Cheops | 2023 Feb 08
During a break from looking at planets around other stars, ESA’s CHaracterising ExOPlanet Satellite (Cheops) mission has observed a dwarf planet in our own Solar System and made a decisive contribution to the discovery of a dense ring of material around it.
The dwarf planet is known as Quaoar. The presence of a ring at a distance of almost seven and a half times the radius of Quaoar, opens up a mystery for astronomers to solve: why has this material not coalesced into a small moon?
The ring was discovered through a series of observations that took place between 2018 to 2021. Using a collection of ground-based telescopes, and the space-based telescope Cheops, astronomers watched as Quaoar crossed in front of a succession of distant stars, briefly blocking out their light as it passed.
Such an event is known as an occultation. Observing how the light from the occulted star drops provides information about the occulting object’s size and shape, and can reveal whether the intervening object has an atmosphere or not. In this case, smaller drops before and after the main occultation betrayed the presence of material in orbit around Quaoar. ...
A dense ring of the trans-Neptunian object Quaoar outside its Roche limit ~ B. E. Morgado et al
- Nature 614(7947):239 (09 Feb 2023) DOI: 10.1038/s41586-022-05629-6 (epdf)