A New Ring System Discovered in our Solar System

A team of international astronomers published a discovery in Nature about a ring system surrounding Quaoar, a dwarf planet that is roughly half the size of Pluto and lies beyond Neptune’s orbit around the Sun. The researchers utilized HiPERCAM, an ultra-sensitive high-speed camera developed by scientists at the University of Sheffield and mounted on the world’s largest optical telescope, the Gran Telescopio Canarias.

The ring system was identified not by direct observation, but by observing an occultation, where the light from a star was blocked by Quaoar. The event lasted a mere minute, but was preceded and followed by two dips in light, signifying the presence of rings.

A New Ring System Discovered in our Solar System
An occultation light curve from Webb’s Near-infrared Camera (NIRCam) Instrument at 1.5 microns wavelength (F150W) shows the dips in brightness of the star (Gaia DR3 6873519665992128512) as Chariklo’s rings passed in front of it on Oct. 18. As seen in the illustration of the occultation event, the star did not pass behind Chariklo from Webb’s viewpoint, but it did pass behind its rings. Each dip actually corresponds to the shadows of two rings around Chariklo, which are ~4 miles (6-7 kilometers) and ~2 miles (2-4 kilometers) wide, and separated by a gap of 5.5 miles (9 kilometers). The two individual rings are not fully resolved in each dip in this light curve. Image credit: NASA, ESA, CSA, Leah Hustak (STScI). Science: Pablo Santos-Sanz (IAA/CSIC), Nicolás Morales (IAA/CSIC), Bruno Morgado (UFRJ, ON/MCTI, LIneA)
A New Ring System Discovered in our Solar System
This video shows observations taken by NASA’s James Webb Space Telescope of a star (fixed in the center of the video) as Chariklo passes in front of it. The video is composed of 63 individual observations with Webb’s Near-infrared Camera Instrument’s view at 1.5 microns wavelength (F150W) obtained over ~1 hour on Oct. 18. Careful analysis of the star’s brightness reveals that the rings of the Chariklo system were clearly detected. Credit: NASA, ESA, CSA, Nicolás Morales (IAA/CSIC)

While ring systems are scarce in the Solar System, with only Saturn, Jupiter, Uranus, and Neptune’s well-known rings and two minor planets, Chariklo and Haumea, possessing them, Quaoar’s ring system is particularly noteworthy because it lies beyond seven planetary radii, twice as far as the previously thought maximum radius according to the Roche limit, where ring systems were thought to be able to persist. For comparison, Saturn’s main rings are located within three planetary radii. This discovery necessitates a rethinking of ring formation theories.

A New Ring System Discovered in our Solar System
This artist’s impression shows how the rings might look from close to the surface of Chariklo. Credit: NASA/JPL

According to Professor Vik Dhillon, a co-author of the study from the University of Sheffield, this new ring system was unexpected and its location so far from Quaoar challenges previous ideas of how ring systems form. The use of HiPERCAM was crucial in making the discovery, as the event was short-lived and the rings are too small and faint to observe directly. The study was led by the Federal University of Rio de Janeiro and involved 59 researchers from all over the world, including six UK universities and was partly funded by the Science and Technology Facilities Council.


READ MORE: This Planet Has Rings 200 Times Larger than Saturn’s


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