ESA's Cheops Mission Detects New Ring System Around Dwarf Planet Quaoar

A dwarf planet in the far reaches of our solar system has a dense ring leaving scientists baffled.

ESA Cheops Spotted A Dense Ring Around Quaoar

Quaoar is one of the 3,000 dwarf planets orbiting the Sun beyond Neptune. It is 690 miles (1,110 kilometers) wide, making it the seventh largest, with Pluto and Eris ranking as the biggest, CNN reported.

Quaoar is a collection of small distant worlds called Trans-Neptunian objects (TNOs). There are about 3000 TNOs identified.

As their name suggests, TNOs are located beyond the orbit of Neptune, in the far reaches of the Solar System.

The European Space Agency's CHaracterising ExOPlanet Satellite (Cheops) mission observed a dense ring at distance almost seven and a half times the radius of Quauar. The researchers couldn't explain why it has not condensed and formed a small ring.

Between 2018 and 2021, a series of observations led to the ring's discovery. Using a collection of ground-based telescopes and the space-based telescope Cheops, astronomers observed as Quaoar crossed in front of a succession of distant stars, momentarily obscuring their light.

This type of occurrence is known as an occultation. Observing how the occulted star's light fades provides information about the occulting object's size and shape and can reveal whether or not the intervening object has an atmosphere. Smaller drops before and after the main occultation revealed the presence of material in orbit around Quaoar in this instance.

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According to Kate Isaak, ESA's Project Scientist for the Cheops mission, the Cheops observations played a crucial role in establishing the presence of a ring around Quaoar. The application of high precision and high cadence photometry transcends the mission's more typical exoplanet science, SciTechDaily reported.

While theorists determine how the Quaoar rings can endure, the Lucky Star project will continue to observe Quaoar and other TNOs as they occult distant stars in order to measure their physical properties and determine how many others have ring systems.

Cheops will resume its original mission of investigating nearby exoplanets.

Why It's Difficult To Study Dwarf Planets

It is challenging to study these dwarf planets due to their small sizes and vast distances. Quaoar orbits the Sun at nearly 44 times the distance between the Sun and Earth.

Consequently, occultations are handy tools. However, until recently, it was difficult to predict precisely when and where they would occur.

The alignment between the occulting object (in this case, the TNO), the star, and the observing telescope must be extremely precise for an occultation to occur.

In the past, it has been nearly impossible to meet the stringent accuracy requirements for seeing an event with certainty. To pursue this objective, the European Research Council Lucky Star project, coordinated by Bruno Sicardy, Sorbonne University & Paris Observatory - PSL (LESIA), was established to predict upcoming occultations by TNOs and to coordinate the observation of these events by professional and amateur observatories worldwide.