2011 WJ ₁₅₇

Asteroid 2011 WJ 157
Properties of the orbit ( animation ) Epoch:  April 27, 2019 ( JD 2,458,600.5)
Orbit type	RKBO 1: 6 , or SDO , "Distant Object"
Major semi-axis	97.941  AU
eccentricity	0.618
Perihelion - aphelion	37.391 AU - 158.49 AU
Inclination of the orbit plane	27.2 °
Length of the ascending node	76.5 °
Argument of the periapsis	59 °
Time of passage of the perihelion	March 19, 2036
Sidereal period	969 a 3.5 M.
Mean orbital velocity	2.985 km / s
Physical Properties
Medium diameter	approx. 468 km
Albedo	0.07-0.09
Absolute brightness	5.0 - 5.3 mag
history
Explorer	Pan-STARRS : B. Gibson T. Goggia N. Primak A. Schultz M. Willman
Date of discovery	November 25, 2011
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items.

2011 WJ ₁₅₇ is a large trans-Neptunian object in the Kuiper belt , which is classified as a resonant Kuiper belt object (1: 6 resonance) or as a scattered disk object (SDO) in terms of orbital dynamics . Because of its size, the asteroid is a dwarf planet candidate .

discovery

2011 WJ ₁₅₇ was discovered on November 25, 2011 by an astronomical team consisting of B. Gibson, T. Goggia, N. Primak, A. Schultz and M. Willman, as part of the Pan-STARRS project with the 1.8-m –Ritchey-Chretien – Telescope (PS1) discovered at Haleakalā Observatory ( Maui ). The discovery was announced on July 26, 2016.

After its discovery, WJ _{157 could be identified} in photos up to February 26, 2010, which were also taken as part of the Pan-STARRS program, and thus its observation period was extended by 21 months in order to calculate its orbit more precisely. In September 2018, there were a total of 50 observations over a period of 6 years. The last observation so far was again carried out in February 2016 at the Pan-STARRS telescope. (As of February 26, 2019)

properties

Orbit

2011 WJ ₁₅₇ orbits the sun in 969.29 years on a strongly elliptical orbit between 37.39  AU and 158.49 AU from its center. The orbital eccentricity is 0.618, the orbit is 27.15 ° inclined to the ecliptic . The planetoid is currently 39.80 AU from the sun. It will next pass through perihelion in 2036, so the last perihelion should have occurred in 1066.

Marc Buie ( DES ) classifies the planetoid as RKBO ( 1: 6 resonance with Neptune ), while the Minor Planet Center classifies it as SDO and generally as a "Distant Object" .

size

A diameter of around 468 km is currently assumed, based on a reflectivity of 7% and an absolute brightness of 5.3  ^m . Assuming a diameter of 468 km, this results in a total surface of around 688,000 km². The apparent brightness of 2011 WJ ₁₅₇ is 21.14  ^m .

Since it can be assumed that 2011 WJ ₁₅₇ is in hydrostatic equilibrium due to its size and must therefore be largely round, it should meet the criteria for classification as a dwarf planet . Mike Brown expects that it is at 2011 WJ ₁₅₇ to possibly is a dwarf planet.

Determinations of the diameter for 2011 WJ ₁₅₇

year	Dimensions km	source
2018	443.0	Johnston
2018	468.0	Brown
The most precise determination is marked in bold .

See also

• List of trans-Neptunian objects
• List of dwarf planets of the solar system
• List of asteroids
• List of moons from asteroids

Web links

• How many dwarf planets are there in the outer solar system? Current list of the largest TNOs from Mike Brown
• Free the dwarf planets! Mike Brown's column on the IAU and the dwarf planets regarding their classifications (23 August 2011)

Individual evidence

1. ^ ^{A b} Marc W. Buie : Orbit Fit and Astrometric record for 11WJ157 . SwRI (Space Science Department). Retrieved February 26, 2019.
2. ↑ ^{a b} MPC : MPEC List Of Centaurs and Scattered-Disk Objects . IAU . Retrieved February 26, 2019.
3. ↑ ^{a b c} 2011 WJ157 at the IAU Minor Planet Center (English) Retrieved on February 26, 2019.
4. ↑ v ≈ π * a / period (1 + sqrt (1-e²))
5. ↑ MPC : MPC / MPO / MPS Archive . IAU . Retrieved February 26, 2019.
6. ↑ MPC : MPEC 2016-O345: 2011 WJ157 . IAU . July 26, 2016. Retrieved February 26, 2019.
7. ↑ 2011 WJ157 in the Small-Body Database of the Jet Propulsion Laboratory (English). Retrieved February 26, 2019.
8. ↑ 2011 WJ157 in the database of the "Asteroids - Dynamic Site" (AstDyS-2, English).
9. ↑ ^{a b} Mike Brown : How many dwarf planets are there in the outer solar system? . CalTech . November 12, 2018. Retrieved February 26, 2019.
10. ^ Wm. R. Johnston: List of Known Trans-Neptunian Objects . Johnston's Archives. October 7, 2018. Retrieved February 26, 2019.