(768325) 2015 BP519
Extreme trans-Neptunian object
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(768325) 2015 BP519, nicknamed Caju,[a] is an extreme trans-Neptunian object from the scattered disc on a highly eccentric and inclined orbit in the outermost region of the Solar System.[7] It has been described as an extended scattered disc object (ESDO),[4] and fits into the group of extreme objects that led to the prediction of Planet Nine, and has the highest orbital inclination of any of these objects.[a]
(first observed only)
| |
| Discovery[1][2] | |
|---|---|
| Discovered by | Dark Energy Survey |
| Discovery site | Cerro Tololo Obs. |
| Discovery date | 17 January 2015 (first observed only) |
| Designations | |
| 2015 BP519 | |
| Caju (nickname)[a] | |
| TNO[3] · ESDO[4] · ETNO distant[2] | |
| Orbital characteristics[3] | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 5 | |
| Observation arc | 3.22 yr (1,176 d) |
| Aphelion | 820 AU |
| Perihelion | 35.2 AU |
| 428.03 AU | |
| Eccentricity | 0.9178 |
| 8856 yr (3,234,488 d) | |
| 358.39° | |
| 0° 0m 0.36s / day | |
| Inclination | 54.125° |
| 135.11° | |
| â 7 September 2058[5] ±1 month | |
| 348.37° | |
| Known satellites | 0 |
| Physical characteristics | |
| 524 km (est.)[6] 584 km (est.)[4] | |
| 0.08 (assumed)[6] 0.09 (assumed)[4] | |
| 21.5 | |
| 4.32[2][3] | |
History
Discovery and observations
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2015 BP519 was first observed on 17 January 2015, by astronomers with the Dark Energy Survey at Cerro Tololo Observatory (W84) in Chile.[1][2] The body's observation arc begins with a precovery taken on 27 November 2014 by astronomers with the Dark Energy Survey using the DECam instrument of the VÃctor M. Blanco Telescope at Cerro Tololo Inter-American Observatory in Chile.[2] Its discovery was reported in a paper published by Dark Energy Survey astronomers in 2018.[7]
Naming
As of 2026, 2015 BP519 has not been officially named yet. However it was given the nickname Caju by Juliette Becker, Fred Adams, Tali Khain, Stephanie Hamilton, and David Gerdes at University of Michigan in a PowerPoint presentation.[a]
Orbit and classification
Orbital characteristics
2015 BP519 orbits the Sun at a distance of 35.2â821 AU once every 8856 years (3,234,488 days; semi-major axis of 428 AU). Its orbit has an exceptionally high eccentricity of 0.92 and an inclination of 54° with respect to the ecliptic.[3] This makes it a probable outlier among the known extreme trans-Neptunian objects.[3][8] It has been described as an extended scattered disc object (ESDO),[4]
Planet Nine hypothesis
2015 BP519 fits into the group of extreme trans-Neptunian objects that originally led to the prediction of Planet Nine.[a]:â13â The group consists of more than a dozen bodies with a perihelion greater than 30 AU and a semi-major axis greater than 250 AU, with 2015 BP519 having the highest orbital inclination of any of these objects.[a] Subsequently, unrefereed work by de la Fuente Marcos (2018) found that 2015 BP519's current orbital orientation in space is not easily explained by the same mechanism that keeps other extreme trans-Neptunian objects together, suggesting that the clustering in its orbital angles cannot be attributed to Planet Nine's influence.[8] However, regardless of the current direction of its orbit, its high orbital inclination appears to fit into the class of high-semi major axis, high-inclination objects predicted by Batygin & Morbedelli (2017) to be generated by Planet Nine.
Physical characteristics
Size and albedo
According to Michael Brown and Johnston's Archive, 2015 BP519 measures 524 and 584 kilometers in diameter based on an assumed albedo of 0.08 and 0.09, respectively.[6][4]
Upcoming observations
As of 2018, no rotational lightcurve of has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.[3] It has not yet been imaged by high-resolution telescopes, so it has no known moons.[9] The Hubble Space Telescope is planned to image 2015 BP519 in 2026, which should determine if it has significantly sized moons.[9]
See also
Notes
- The nickname "Caju" is mentioned in the downloadable PowerPoint presentation "Evaluating the Dynamical Stability of Outer Solar System Objects in the Presence of Planet Nine", by Juliette Becker, Fred Adams, Tali Khain, Stephanie Hamilton, and David Gerdes at University of Michigan.