Second ring around the dwarf planet candidate Quaoar

28 Apr. (EUROPE PRESS) –

A large team of astronomers has discovered evidence that the distant TNO (trans-Neptunian object) Quaoar it is surrounded by a second ring.

With more than 1,000 km in diameter, Quaoar is a dwarf planet candidate. TNOs, like Quaoar, are largely intact fossils from the formation of the Solar System. Therefore, cataloging its physical characteristics is essential to understand how the Solar System formed and evolved to the present day.

The discovery of the second ring comes just two months after the same team revealed the Quaoar’s first ringindicating that the trans-Neptunian object system is more complex than previously thought, since it has a second ring that is more internal than the one previously revealed.

Both discoveries were made using the stellar occultation technique, when an object from the Solar System passes in front of a star and blocks its light for a few moments.

The discovery of the second Quaoar ring was published in the journal Astronomy & Astrophysics Letters on April 28 and the lead author of the study is Chrystian Luciano Pereira, a PhD student at the National Observatory of Brazil.

As reported by the researchers it’s a statementunlike the rings observed on Chariklo, Haumea and the four giant planets, Quaoar’s rings are in an unexpected region, well beyond the Roche limit for the body (for Quaoar, this limit is estimated to be 1,780 km from the center of the body).

The Roche limit is a region where the tidal forces of the central body are in equilibrium with the mutual attraction of the particles that form a ring, thus avoiding the accumulation of these particles in satellites.

In other words, it is an “imaginary line” that defines the minimum distance that an object can get close to another before being disintegrated by the gravitational force. When an object is within the Roche limit, it is expected to disintegrate and form a ring around the central object. On the other hand, if it is beyond this limit, as is the case with Quaoar’s rings, the parts are expected to aggregate and form a satellite, and not a ring as is the case.

From the observation data for the first ring (Q1R), the researchers were able to detect the second ring (Q2R), which is actually closer to the TNO. Q2R is about 10 km wide and despite being closer to Quaoar, it is also outside the Roche limit, orbiting 2,520 km from the center of the object.

To learn more about Quaoar and its curious ring, the team organized an observing campaign of a stellar occultation observed on August 9, 2022, involving amateur and professional telescopes, such as Gemini North and Canada-France- Hawaii Telescope (CFHT), with a diameter of 8.1 and 3.6 meters, respectively.

The high performance of the instruments attached to the Gemini North and CFHT telescopes, the ‘Alopeke and WIRcam cameras, respectively, combined with their location atop Mauna Kea in Hawaii, allowed to obtain light curves of excellent quality.