 2023 KQ14 imaged by theDark Energy Camera on 7 June 2021 | |
| Discovery[1] | |
|---|---|
| Discovered by | FOSSIL[a] |
| Discovery site | Mauna Kea Obs. |
| Discovery date | 16 May 2023[3] |
| Designations | |
| 2023 KQ14 | |
| Ammonite (nickname)[1] | |
| ETNO · sednoid | |
| Orbital characteristics (barycentric)[4] | |
| Epoch 5 May 2025 (JD 2460800.5) | |
| Uncertainty parameter 3[5] | |
| Observation arc | 19.23yr (7,024 days) |
| Earliestprecovery date | 11 April 2005[3] |
| Aphelion | 438.1AU |
| Perihelion | 65.9 AU |
| 251.9±0.3 AU[1][4] | |
| Eccentricity | 0.7383±0.0003[1] |
| 3,998 yr[4] | |
| 356.56°[4] | |
| 0° 0m 0.888s / day | |
| Inclination | 10.98°[1] |
| 72.104°±0.001°[1] | |
| ≈ February 2063[6] | |
| 198.74° | |
| Physical characteristics | |
| 220–380 km(calc. foralbedo 0.05–0.15)[1] | |
| |
| 25.4[8] | |
| 6.77±0.43[5] | |
2023 KQ14, informally nicknamedAmmonite, is atrans-Neptunian object (TNO) orbiting theSun on an extremely wideelliptical orbit. It was discovered by theSubaru Telescope atopMauna Kea on 16 May 2023, as part of an internationally ledastronomical survey known as the "Formation of the Outer Solar System: an Icy Legacy" (FOSSIL) survey.2023 KQ14 is unusual because the direction of itsorbital apsides is not aligned with those of previously known TNOs with high-perihelion elliptical orbits (sometimes known assednoids), which challenges the hypothesis that an unseen distant planet ("Planet Nine") could be aligning their orbits.[2]2023 KQ14 likely has a diameter between 220 and 380 km (140 and 240 mi).
2023 KQ14 was discovered by the 8.2-meterSubaru Telescope atMauna Kea Observatory, Hawaii, on 16 May 2023,[3] during the operation of the "Formation of the Outer Solar System: an Icy Legacy" (FOSSIL)astronomical survey.[1] The FOSSIL survey, which is an international collaboration of astronomers primarily from Japan and Taiwan, began in 2020[2] with the initial goal of detecting faintJupiter trojans andtrans-Neptunian objects (TNOs) across the sky.[9] The survey discovered2023 KQ14 during the first year of its second phase ("FOSSIL II"), when it began focusing on detecting TNOs only.[1]
Astronomers of the FOSSIL survey identified2023 KQ14 in FOSSIL observations from March to August 2023 and noticed that it was extraordinarily far from the Sun.[1] To better determine2023 KQ14's orbit and distance,[1] astronomersYing-Tung Chen andJohn J. Kavelaars reobserved the object with theCanada–France–Hawaii Telescope in July 2024.[8] These extra observations allowed Chen toprecover2023 KQ14 in archivalDark Energy Camera images from June 2021 and May 2014.[1][8] The discovery of the object was announced by theMinor Planet Center (MPC) on 14 April 2025,[8] and a research paper detailing the discovery was published inNature Astronomy on 14 July 2025.[1]
The object has theminor planetprovisional designation2023 KQ14, which was given by the MPC in the discovery announcement.[8] The provisional designation indicates the year and half-month of its discovery date.[10] The object was unofficially nicknamed "Ammonite" by the FOSSIL team, after theammonite fossil which serves as an analogy to the object's fossilized orbit since thebeginning of the Solar System.[2] An official name can be given once2023 KQ14 is given a permanentminor planet catalog number by the MPC.[11]
2023 KQ14 follows an extremely wideelliptical orbit around the Sun, whose distance with respect to theSolar System barycenter[b] ranges from 65.9 astronomical units (AU) atperihelion to438 AU ataphelion.[4] It takes roughly 4,000 years for2023 KQ14 to complete one orbit.[4]2023 KQ14's barycentric orbit has asemi-major axis of252 AU,eccentricity of 0.739, and aninclination of 11° with respect to theecliptic.[1][4]2023 KQ14 was71.0 AU away from the Sun when it was discovered,[1] and it will pass perihelion in February 2063.[6]
2023 KQ14 is one of the four known distant TNOs (as of 2025[update]) whose perihelion distances are greater thanq =60 AU and whose semi-major axes are greater thana =200 AU.[1] These TNOs are sometimes known assednoids.[13][14]2023 KQ14 has the third farthest perihelion among the known TNOs, following2012 VP113 (q =80.6 AU) andSedna (q =76.3 AU).[1]2023 KQ14 is far enough away fromNeptune (a =30 AU) that its orbit is barely affected by the planet's gravity.[2][1] Because2023 KQ14 isdetached from thegravitational influence of the known planets, its orbit is dynamically stable for billions of years and had likely remained unchanged since the beginning of the Solar System 4.5 billion years ago.[2][1] This suggests that external gravitational influences must be responsible for forming the orbits of2023 KQ14 and the sednoids—possible sources include apassing rogue star or planet, a distant unseen planet ("Planet Nine"), migration of the Sun through different parts of theMilky Way, or other stars in the Sun'sbirth cluster.[1]
The direction of2023 KQ14'sorbital apsides, orlongitude of perihelion (ϖ), is not aligned with those of the three previously known sednoids.[1] Whereas the orbits of the three previously known sednoids appear to cluster betweenϖ = 0° andϖ = 90°, the orbit of2023 KQ14 points in the opposite direction[1] atϖ = 271°.[c] The anti-aligned orbit of2023 KQ14 challenges but does not rule out the Planet Nine hypothesis, which was originally proposed to explain the apparent orbital clustering of the three previously known sednoids.[2][1][14] If Planet Nine exists, then it should orbit the Sun at a farther distance (using the 2024 prediction ofa =500+170
−120 AU) in order to keep the orbit of2023 KQ14 stable for at least one billion years.[1]
Simulations without Planet Nine by Ying-Tung Chen and collaborators in 2025 suggested that there is a 97% chance that2023 KQ14's orbit was previously aligned with the three known sednoids 4.2 billion years ago, or roughly 300 million years after the formation of the Solar System, if the orbits of all sednoids wereapsidally precessing due to perturbations by the giant planets.[1] This primordial cluster of aligned orbits would have then gradually dispersed due to the sednoids' differing apsidal precession rates.[1] In this case, this would suggest that the sednoids' orbits were perturbed by a passing rogue planet early in the Solar System's history.[1]
2023 KQ14 appears extremely faint from Earth, with anapparent magnitude of 25.4.[8] Its brightness suggests a diameter between 220 and 380 km (140 and 240 mi), if it has ageometric albedo between 0.05 and 0.15.[1] Observations by theMagellan Telescopes in April 2025 showed no significant brightness variations over time, suggesting that2023 KQ14 has either a slow rotation or a uniform shape or albedo.[7] Observations of2023 KQ14 in differentlight filters show that it has a moderately red color similar to other TNOs and sednoids.[7]
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