65489 Ceto I Phorcys
65489 Ceto I Phorcys is a binary celestial system located in the outer solar system, consisting of the asteroid Ceto and its companion moon, Phorcys. Both objects are similar in size, with Ceto measuring approximately 174 kilometers (108 miles) in diameter and Phorcys about 132 kilometers (82 miles). This unique configuration means they orbit a common center of gravity, classifying them as a binary centaur, which follows an unstable orbit that intersects the paths of Uranus and Neptune. Additionally, because part of their orbit extends beyond Neptune, they are categorized as a binary trans-Neptunian object.
Ceto was discovered in 2003, but Phorcys was not identified until 2006, following analysis that revealed Ceto’s orbit could only be explained by the gravitational influence of a nearby object. Phorcys is primarily made of rock and ice, has a low internal temperature, and features a rough surface texture, while the mutual orbit of both objects is nearly circular. The naming of the two bodies reflects their mythological roots; Ceto is named after the Greek sea goddess associated with the dangers of the sea, while Phorcys, her husband, is also a significant figure in Greek mythology. This binary system provides valuable insights into the characteristics and composition of celestial objects in our solar system.
65489 Ceto I Phorcys
FIELDS OF STUDY: Sub-planet Astronomy; Astrophysics; Cosmology
ABSTRACT: (65489) Ceto I Phorcys is the companion object of the small solar system body (65489) Ceto. Because the two objects orbit a common center of mass and are close in size, they form a binary system. Their orbit around the sun goes well beyond Neptune, classifying the pair as a binary trans-Neptunian object. It is also a binary centaur.
Discovery of Phorcys
(65489) Ceto I Phorcys is the companion object of the asteroid Ceto in the outer solar system. Although Phorcys is officially Ceto’s moon, the two are of a similar size and orbit a common center of gravity, making them a binary system. Ceto and Phorcys are considered a binary centaur because they follow an unstable orbit that crosses the orbital paths of both Uranus and Neptune. Because part of their orbit takes them beyond Neptune, they are also considered a binary trans-Neptunian object (TNO).
Ceto was discovered in 2003, but its binary nature was not recognized at the time. Phorcys’s proximity to Ceto made it difficult to see, even with the Hubble Space Telescope. However, a research team noticed that Ceto followed an orbit that could only be explained by the presence of another object in close proximity exerting a tidal force on it. Image analysis led to the discovery of Phorcys in 2006.
Nature of Phorcys
Phorcys’s discovery was important because it helped researchers calculate the likely size and physical composition of both objects. Data has shown Phorcys to be a relatively small space object, about 132 kilometers (82 miles) in diameter—close in size to Ceto, which has an estimated diameter of 174 kilometers (108 miles). Phorcys is composed of rock and ice, with a low internal temperature and an extremely rough surface. It is relatively dense, and its mutual orbit with Ceto is nearly circular.
Pair Naming
Ceto was named for the Greek sea goddess who represented the unknown dangers of the sea. Following the conventions of the International Astronomical Union (IAU), Phorcys was named for a closely related figure from Greek mythology. Phorcys was Ceto’s husband and an ancient sea god.
PRINCIPAL TERMS
- binary centaur: two small solar system bodies that orbit around a common center of mass while simultaneously following a larger, nonresonant, unstable orbit around the sun that crosses the path of one or more outer planets.
- binary trans-Neptunian object: two minor planets that orbit around a common center of mass while simultaneously following a larger orbit around the sun at a greater average distance than Neptune.
- Ceto: an asteroid in the outer solar system that forms a binary system with Phorcys.
- tidal force: the effect of variation in the gravitational pull exerted by celestial bodies on other space objects nearby, causing distortions in shape.
Bibliography
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