2015 BP₅₁₉, nicknamed Caju,[lower-alpha 1] 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 was first observed on 17 January 2015, by astronomers with the Dark Energy Survey at Cerro Tololo Observatory (W84) in Chile.[1][2] 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.[lower-alpha 1]

2015 BP₅₁₉

Orbital diagram of 2015 BP519 and other extreme objects along with hypothetical Planet Nine
Discovery[1][2]
Discovered by	Dark Energy Survey
Discovery site	Cerro Tololo Obs.
Discovery date	17 January 2015 (first observed only)
Designations
MPC designation	2015 BP519
Alternative designations	Caju (nickname)[lower-alpha 1]
Minor planet category	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
Semi-major axis	428.03 AU
Eccentricity	0.9178
Orbital period (sidereal)	8856 yr (3,234,488 d)
Mean anomaly	358.39°
Mean motion	0° 0m 0.36s / day
Inclination	54.125°
Longitude of ascending node	135.11°
Time of perihelion	≈ 7 September 2058[5] ±1 month
Argument of perihelion	348.37°
Physical characteristics
Mean diameter	524 km (est.)[6] 584 km (est.)[4]
Geometric albedo	0.08 (assumed)[6] 0.09 (assumed)[4]
Apparent magnitude	21.5
Absolute magnitude (H)	4.4[2][3]

Orbit and classification

2015 BP₅₁₉ orbits the Sun at a distance of 35.2–821 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]

Planet Nine

2015 BP₅₁₉ fits into the group of extreme trans-Neptunian objects that originally led to the prediction of Planet Nine.[lower-alpha 1]^: 13 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.[lower-alpha 1] 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.

Numbering and naming

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 Víctor 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]

Physical characteristics

According to Michael Brown and the Johnston's archive, 2015 BP₅₁₉ measures 524 and 584 kilometers in diameter based on an assumed albedo of 0.08 and 0.09, respectively.[4] As of 2018, no rotational lightcurve of has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.[3]

See also

• List of unnumbered trans-Neptunian objects § 2015 BP519
• Sedna

Notes

References

External links

• Discovery and Dynamical Analysis of an Extreme Trans-Neptunian Object with a High Orbital Inclination, 14 May 2018
• A New World's Extraordinary Orbit Points to Planet Nine 15 May 2018
• 2015 BP519 at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 2015 BP519 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

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