2017 OF201
 Orbit compared to Sedna | |
| Discovery | |
|---|---|
| Discovered by | Sihao Cheng, Jiaxuan Li, Eritas Yang |
| Discovery site | Cerro Tololo Inter-American Observatory |
| Designations | |
| 2017 OF201 | |
| TNO, SDO and eTNO | |
| Orbital characteristics | |
| Epoch 2025-May-05 (JD 2460800.5) | |
| Uncertainty parameter 3 | |
| Observation arc | 7.17 yr (2,618 days) (using 19 observations) |
| Earliest precovery date | 2011-08-31 |
| Aphelion | 1630 AU (barycentric)[1] 1632±14 AU[2] 1700±60 AU |
| Perihelion | 44.9 AU[2][3] |
| 840 AU (barycentric)[2] | |
| Eccentricity | 0.95 |
| 24200 years (barycentric)[1] 24300 years (barycentric)[2] 25000±1000 yr | |
| 1.3° | |
| 0° 38m 7.8s / day | |
| Inclination | 16.21° |
| 329° | |
| November 1930 ± 1 month | |
| 338° | |
| Physical characteristics | |
| ∼ 550 to 850 km (calc. for a typical TNO albedo of 0.15) | |
| 22.8 | |
| 3.5±0.5 | |
2017 OF201 is an extreme trans-Neptunian object and dwarf planet candidate, estimated to be at least 550 kilometres (340 miles) in diameter. With an absolute magnitude of between 3 and 4, it may be the brightest known object in the Solar System that does not have a directly estimated size. Its last perihelion was around November 1930. As of 2025, its current distance from the Sun is 90.5 AU, making it one of the most distant Solar System objects observed.[2]
History
[edit]Discovery of 2017 OF201 was submitted on May 21, 2025, by Sihao Cheng, Jiaxuan Li, and Eritas Yang.[2] The announcement of 2017 OF201 challenges the existence of Planet Nine. The orientations of the orbits of extreme trans-Neptunian objects tend to cluster. This clustering led to the hypothesis that a possible distant planet has influenced those orbits. However, the orbit of 2017 OF201 is one of the few (such as 2013 FT28 and 2015 KG163) that is anti-aligned to the calculated orbit of Planet Nine. Modelling suggests the hypothetical planet would have ejected 2017 OF201 from its current orbit over times scales of less than 100 million years, though it could be in a temporary orbit.[2][4]
2017 OF201 was discovered thanks to data from the Dark Energy Camera that a team of astronomers led by Cheng of the Institute for Advanced Study analyzed for potential faint dwarf planets.[5] Findings were then sent to the Canada France Hawaii telescope to see if their detection could be re-created and verified.[5] Cheng and his co-discoverer Jiaxuan Li have been amateur astronomers since they were in elementary school.[5] The existence of 2017 OF201, which also means that there are likely many other similar objects that are just obscured from earth observation.[5] Konstantin Batygin, the creator of the Planet Nine hypothesis has claimed that the discovery of 2017 OF201 means nothing in relation to the theory due to 2017 OF201 "strongly interacting with Neptune" and claiming its orbit is unstable, which Cheng refutes.[5]
Orbit
[edit]2017 OF201 orbits far beyond Neptune at an average distance of 880 astronomical units (AU), taking around 25,000 years to complete an orbit around the Sun. 2017 OF201 has an orbit with an orbital eccentricity of 0.95 and an orbital inclination of 16.2°. 2017 OF201 has one of the most distant aphelia of known trans-Neptunian objects, being similar to 2013 SY99 and surpassed by 2019 EU5, all three of which have perihelia inside the Kuiper cliff and so have or have had some interaction with Neptune. This places this object near the estimated boundary of the scattered disc region and the inner Oort cloud when the object is at its maximum distance of about 1,630 astronomical units (0.0258 light-years) from the Sun. The orbit of 2017 OF201 is shaped by both Neptune and the galactic tide over billions of years.[2][6]
Due to the extremely elongated track of its orbit, 2017 OF201 the Sun makes it too faint to see for more than 99% of its orbit.[5] Due to this co-discoverer Eritas Yang stated that its discovery makes it likely that there are thousands of similar objects that simply haven't been observed yet due to visibility.[5]
Physical characteristics
[edit]The diameter of 2017 OF201 is unknown, but it is estimated to be somewhere between 550-850 kilometres in diameter, placing it within the range of possible dwarf planets. For reference, Pluto is 2,376.6 kilometres in diameter, and Quaoar, which is widely accepted as a dwarf planet, is 1,090 kilometres in diameter.[2][4]
References
[edit]- ^ a b Horizons output. "Barycentric Osculating Orbital Elements for 2017 OF201". Solution using the Solar System Barycenter. Ephemeris Type:Elements and Center:@0
- ^ a b c d e f g h i Cheng, Sihao; Li, Jiaxuan; Yang, Eritas (2025). "Discovery of a dwarf planet candidate in an extremely wide orbit: 2017 OF201". arXiv:2505.15806 [astro-ph.EP].
- ^ "1930 Perihelion" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 2025-05-27.
- ^ a b "An Extreme Cousin for Pluto? Possible Dwarf Planet Discovered at Solar System's Edge". www.ias.edu (Press release). Institute for Advanced Study. 2025-05-20. Retrieved 2025-05-23.
- ^ a b c d e f g Chandler, David L. "Another Dwarf Planet in Our Solar System?". Sky & Telescope. Retrieved 29 May 2025.
- ^ Sandberg, Lee (May 2025). "An extreme cousin for Pluto? Possible dwarf planet discovered at solar system's edge". phys.org. Retrieved 2025-05-23.
External links
[edit]- 2017 OF201 at the JPL Small-Body Database
- Spin view of orbit, Sky trajectory 2011-2027 Tony Dunn
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| Candidate (for TNOs, D+1σ ≥ 700 km or H ≤ 4.2) |
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