Weywot, officially (50000) Quaoar I Weywot, is the only known moon of the trans-Neptunian planetoid 50000 Quaoar. Discovered by Michael Brown and T.A. Suer using images acquired by the Hubble Space Telescope on 14 February 2006, its existence was announced in an IAU Circular notice published on 22 February 2007. Weywot has an estimated diameter of (approximately 15% of its primary). The satellite was found at 0.35

arcsecond A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

s from Quaoar with an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

difference of 5.6.

Orbit

Two possible orbits for Weywot have been determined from the observations: the first is a

prograde orbit Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure). It may also describe other motions such as precession or ...

with an

orbital inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Earth ...

of 14 degrees, the second a

retrograde orbit Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure). It may also describe other motions such as precession or ...

with an orbital inclination of 30 degrees (150 degrees); the other parameters are very similar between the two orbits. Weywot orbits at a distance of from Quaoar and has an

orbital eccentricity In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values betwee ...

of about 0.14. It completes one orbit in about 12.5 days.

Physical characteristics

Weywot is calculated to be around in diameter ( to of Quaoar), based on a stellar

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

by Weywot in 2019. Weywot had previously been estimated to be in diameter, based on observations with the Herschel Space Observatory in 2013. Prior to that, Weywot was calculated be about 74 km ( of Quaoar) from its apparent magnitude, under the assumption that Weywot had an equal

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

and density to Quaoar. Given that diameter, Weywot was estimated to only have the mass of Quaoar. Weywot therefore appears to be much darker than Quaoar; assuming comparable densities, it would be approximately the mass of Quaoar, or . However, among trans-Neptunian objects, darker albedos correlate with lower densities, so Weywot is likely to mass less than this.

Name

Upon discovery, Weywot was issued a provisional designation, . Brown left the choice of a name up to the

Tongva The Tongva ( ) are an Indigenous people of California from the Los Angeles Basin and the Southern Channel Islands, an area covering approximately . Some descendants of the people prefer Kizh as an endonym that, they argue, is more historically ...

, whose creator-god Quaoar had been named after. The Tongva chose the sky god

Weywot Weywot, officially (50000) Quaoar I Weywot, is the only known moon of the trans-Neptunian planetoid 50000 Quaoar. Discovered by Michael Brown and T.A. Suer using images acquired by the Hubble Space Telescope on 14 February 2006, its existence wa ...

, son of Quaoar. The naming of Weywot was officially announced in a

Minor Planet Circular The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

notice published on 4 October 2009. It was thought that Weywot may have originated from a collision with Quaoar and another large Kuiper belt object.

References

{{Moons of dwarf planets 50000 Quaoar Trans-Neptunian satellites Discoveries by Michael E. Brown Objects observed by stellar occultation