2015 GT50

2015 GT₅₀, previously known as o5p060, is a trans-Neptunian object orbiting in the Kuiper belt of the outermost Solar System. It was first observed by the Outer Solar System Origins Survey using the Canada–France–Hawaii Telescope at Mauna Kea on 13 April 2015.

2015 GT₅₀

The orbits of 2015 GT50 (bottom; orange) and other detached objects, along with the hypothetical Planet Nine's orbit (right; green)
Discovery
Discovered by	OSSOS
Discovery site	Mauna Kea Obs.
Discovery date	13 April 2015
Designations
Alternative designations	o5p060[1]
Minor planet category	Detached object
Orbital characteristics
Epoch JDT 2458000.5
Observation arc	824 days (2.26 yr)
Earliest precovery date	20 February 2015
Aphelion	631.89 AU
Perihelion	38.45 AU
Semi-major axis	335.169 AU
Eccentricity	0.885
Orbital period (sidereal)	6,140 years
Inclination	8.779°
Longitude of ascending node	46.100°
Argument of perihelion	129.236°
Physical characteristics
Apparent magnitude	8.5

Description

It is one a small number of detached objects with perihelion distances of 30 AU or more, and semi-major axes of 250 AU or more.^[2] Such objects cannot reach such orbits without some perturbing object, which has led to the Planet Nine hypothesis, that a massive trans-Neptunian planet is the perturber. However 2015 GT₅₀ is an interesting outlier of these trans-Neptunian objects that make one of the lines of evidence for Planet Nine. Unlike the others, the shape of whose orbits (longitudes of perihelion) either cluster in anti-alignment with the modeled orbit of Planet Nine or cluster in alignment with it, 2015 GT₅₀'s major axis is almost at a right angle to that of the putative planet. Konstantin Batygin of Caltech suggests that this is only a cosmetic disagreement with his and Mike Brown's predictions for the positions of these bodies. In fact, he notes that without having to change the putative orbit of Planet Nine, 2015 GT₅₀ falls into one of the predicted resonant orbits. This, he notes, may be a coincidence.^[3] This conclusion, however, is not unanimous, and others have instead suggested that the existence of a population of objects with orbital characteristics similar to those of 2015 GT₅₀ may be at odds with the Planet Nine hypothesis.^[4]

Closeup of current position near perihelion, passing across the top side of this view