| Discovery[1] | |
|---|---|
| Discovered by | LINEAR |
| Discovery site | Socorro, New Mexico, United States |
| Discovery date | 3 December 1999 |
| Designations | |
| (36256)1999 XT17 | |
| 1979 UU3 · 1979 VH · 1989 TF2 | |
| Main belt | |
| Orbital characteristics[2] | |
| Epoch 21 November 2025 (JD 2461000.5) | |
| Uncertainty parameter 0 | |
| Aphelion | 3.3049AU |
| Perihelion | 2.5722 AU |
| 2.9386 A2 | |
| Eccentricity | 0.1247 |
| 5.0374 yr (1839.9 d) | |
| 356.163° | |
| 0.1957° / d | |
| Inclination | 10.9816° |
| 31.122° | |
| 59.833° | |
| Jupiter MOID | 2.0141 AU |
| TJupiter | 3.235 |
| Physical characteristics | |
| 10.21±0.32 km[2] | |
| 4.108048 h[2] | |
| 0.186±0.033[2] | |
| A-type[3]: 3 | |
| 12.54[2] | |
(36256)1999 XT17 is an unnamedasteroid located in themain asteroid belt. Discovered on 3 December 1999 by theLincoln Near-Earth Asteroid Research (LINEAR) program, it was initially observed as alost asteroid in 1979. Around 10 kilometres (6.2 mi) in size, it is theparent body of a small and unusualasteroid family. Many members of this asteroid family, including1999 XT17, are olivine-rich asteroids, suggesting that they may have originated from themantle of a destroyedplanetesimal.
1999 XT17 was first observed by theCrimean Astrophysical Observatory on 16 October 1979 and was assigned theprovisional designation1979 UU3 by theMinor Planet Center (MPC).[4]: 18 It was observed by the Crimean Astrophysical Observatory again on 11 November of that year; believed to be a different object, it was assigned a second provisional designation,1979 VH.[4]: 19 It subsequently became alost asteroid. It was briefly observed by Klet Observatory in October 1989, but was not identified as the object observed at the Crimean Astrophysical Observatory a decade earlier.[1] The asteroid was observed again in late 1999 by theLincoln Near-Earth Asteroid Research (LINEAR) program, located at theExperimental Test Site (ETS) inSocorro, New Mexico, United States.[1] 3 December 1999 is marked as the official discovery date of the asteroid, and it was given its primary provisional designation1999 XT17.[2]
Once1999 XT17's orbit was sufficiently determined, it was assigned the number (36256) by the MPC on 27 February 2002.[5] The MPC also linked the 1979 and 1989 observations to the asteroid that same day.[6]: 437 As of 2025[update], it is unnamed.[2]
1999 XT17 orbits the Sun at an average distance—itssemi-major axis—of 2.94astronomical units (AU), placing it in themain asteroid belt. Along its 5.04 year long orbit, its distance from the Sun varies from 2.57 AU atperihelion to 3.31 AU ataphelion due to itsorbital eccentricity of 0.12. The asteroid's orbit is inclined by 10.98° with respect to theecliptic plane.[2]
1999 XT17 is the parent body of a smallasteroid family (FIN:629) with 58 identified members.[7]: 438 [8]: 316 The family lies near the outer edge of the "pristine zone", a region of the outer main belt bounded by the 5:2 and 7:3mean motion resonances (MMRs) with Jupiter at 2.825 AU and 2.955 AU, respectively.[3]: 2 This zone, whose name was coined in a 2013 study led by Miroslav Brož, is deficient in smaller asteroids. The bounding resonances prevent the migration of asteroids from outside the zone, and it may represent the primordial main belt population before the creation of large asteroid families.[9]: 2, 10
The1999 XT17 family is unusually rich inolivine-bearingA-type asteroids. Of the 36 members that have aspectral classification, 44.4% are A-types—an abundance seven times higher than the main belt average.[3]: 3 [10]: 6 The second-most abundant spectral type found within the family is theS-complex, comprising 30.5% of the classified population.[3]: 3 However, S-complex members of the family may have originated from other asteroid families, becoming interlopers of the1999 XT17 family. None of the five S-complex families residing within the pristine zone are close enough to the1999 XT17 family to contaminate it.[a] Instead, theEos family is the likeliest source of contamination. The Eos family resides outside of the pristine zone, but some of its members migrated across the 7:3 Jovian MMR fast enough to avoid destabilization and now contaminate the pristine zone. A 2024 study led by M. Galinier noted that all of the1999 XT17 family's S-complex members have orbits similar to known Eos family migrants, suggesting that only the A-type members are truly related to each other. If the1999 XT17 family only consists of A-type asteroids, then it likely originated from themantle of a partially or fully differentiatedplanetesimal.[3]: 4–5
1999 XT17 is estimated to be around 10.2 kilometres (6.3 mi) in diameter, with ageometric albedo of 0.19.Photometric observations from theAsteroid Terrestrial-impact Last Alert System (ATLAS) suggests that it has arotation period of 4.11 hours.[2]Spectroscopic observations of1999 XT17 in thenear-infrared show that it is anA-type asteroid in theBus–DeMeo and Mahlke classification schemes.[3]: 2 Comparison of1999 XT17's visible and near-infrared spectrum to meteorites with similar spectra suggests that it is mostly composed of pure olivine.[3]: 5
