A recently identified moon boasts an estimated diameter of 38 kilometers (23.6 miles) and a V magnitude of 28, marking it as the faintest moon ever found orbiting a trans-Neptunian object.
This image of Quaor and its satellite Waywot was captured by the NASA/ESA Hubble Space Telescope on February 14, 2006. Image credit: NASA / ESA / Hubble / Michael E. Brown.
Discovered on June 4, 2002, Quaor is a trans-Neptunian object that measures approximately 1,100 km (690 miles) in diameter.
Similar to the dwarf planet Pluto, this object is located in the Kuiper Belt, which is a region filled with icy debris and comet-like entities.
The moon, known as 2002 LM60, orbits between 45.1 and 45.6 astronomical units (AU) from the Sun, completing a full orbit every 284.5 years.
In 2006, astronomers found Quaor’s moon, Waywot. This moon has a diameter of 80 km (50 miles) and orbits at a radius of 24 km around Quaor.
Recently, two rings named Q1R and Q2R were discovered encircling Quaor.
“Over the past decade, stellar occultations have shown that rings can exist around small celestial bodies,” explained Benjamin Proudfoot, an astronomer at the Florida Space Institute, along with his colleagues.
“Of these small ring systems, the ring around Quaor is perhaps the most enigmatic.”
“The two rings located so far are situated beyond Roche’s limits and exhibit heterogeneity.”
“Quaor’s outer ring, referred to as Q1R, seems to be partially confined by mean-motion resonance with Quaor’s moon Waywot and by spin-orbit resonance due to Quaor’s triaxial shape.”
“The inner ring, Q2R, appears to be less dense, and its confinement is more ambiguous.”
“Recently, simultaneous dropouts from two telescopes during a stellar occultation indicated the presence of a previously unknown dense ring surrounding a moon, or Quaor.”
“The dropout duration suggests a minimum diameter/width of 30 km.”
Artist’s rendition of Quaor and its two rings, featuring Quaor’s moon Waywot on the left. Image credit: ESA/Sci.News.
In a recent study, astronomers set out to determine the orbit of this new satellite candidate.
They discovered that the object likely follows a 3.6-day orbit, closely aligned with a 5:3 mean-motion resonance with Quaor’s outermost known ring.
Additional observations of satellites using stellar occultations were also considered.
“Quaoar will be favorably positioned within the Scute nebula for the next decade, offering optimal conditions for occultation during its 286-year orbit,” the researchers stated.
“Current ground-based and space telescopes may struggle to detect the newly identified moon due to its dimness (9 to 10 magnitudes fainter than Quaor) and its angular distance from Quaor.”
“Our analysis of Webb/NIRCam images from the Quaor system has not shown any definitive evidence of the satellite,” they remarked.
“Achieving direct imaging with present technologies would necessitate considerable telescope time to reacquire the satellite’s phase, even if it were indeed visible.”
“However, future telescope generations will likely be able to detect it easily.”
The discovery of this new moon offers insights suggesting that the ring surrounding Quaor was likely once part of a broad impact disk, which may have undergone significant changes since its formation, the researchers indicated.
“Studying the formation and evolution of the lunar disk system can yield valuable information about the origins of trans-Neptunian objects,” the researchers remarked.
“We advocate for advanced tidal mechanics, hydrodynamics, and collisional modeling of the Quaor system.”
The team’s paper has been submitted for publication in Astrophysical Journal Letters.
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Benjamin Proudfoot et al. 2025. Orbital characteristics of a newly discovered small satellite around Quaor. APJL in press. arXiv: 2511.07370
Source: www.sci.news
