474640 Alicanto

Discovery and orbit

Alicanto was discovered by American astronomer A. C. Becker with the ESSENCE supernova survey on 6 November 2004 observing with the 4-meter Blanco Telescope from Cerro Tololo Inter-American Observatory. Precovery images have been found back to 26 September 2000. Alicanto was observed by the Hubble Space Telescope in November 2008, and found not to have any detectable companions. It reached perihelion (closest approach to the Sun) in 2009 and is currently 47.7 AU from the Sun. It was in the constellation of Cetus until 2019. It comes to opposition at the start of November.

With a perihelion greater than 40 AU, Alicanto is an extreme trans-Neptunian object which are practically detached from Neptune's gravitational influence. Its orbit is characterized by high eccentricity (0.850), moderate inclination (25.58°) and a semi-major axis of 316 AU. Upon discovery, it was classified as a trans-Neptunian object. Its orbit is well determined; as of 11 January 2017 its orbital solution is based on 34 observations spanning a data-arc of 5821 days. Alicanto's orbit is similar to that of , indicating that they may have both been thrown onto the orbit by the same body, or that they may have been the same object (single or binary) at one point.

Numerical simulations based on models of Solar System formation suggest this object, along with Sedna, may be part of the inner edge of the Oort cloud.

Naming

On 14 May 2021, the object was named by the Working Group for Small Bodies Nomenclature (WGSBN) after Alicanto from Chilean mythology. The nocturnal bird of the Atacama Desert has wings that shine at night with beautiful, metallic colors.

Physical characteristics

Alicanto has an absolute magnitude of 6.5 which gives a characteristic diameter of 130 to 300 km for an assumed albedo in the range 0.25–0.05.

Michael Brown's website lists it with a diameter of 314 km based on an assumed albedo of 0.04. The albedo is expected to be low because the object has a blue (neutral) color. However, if the albedo is higher, the object could easily be half that size.

Alicanto's visible spectrum is very different from that of 90377 Sedna. The value of its spectral slope suggests that the surface of this object can have pure methane ices (like in the case of Pluto) and highly processed carbons, including some amorphous silicates. Its spectral slope is similar to that of .

Comparison

References

|author-link=Marc W. Buie |url-status=dead

|author-link=Michael E. Brown

References

1. [https://www.minorplanetcenter.net/iau/mpec/K07/K07S29.html Discovery MPEC]
2. (2015-02-01). "Re-assessing the formation of the inner Oort cloud in an embedded star cluster – II. Probing the inner edge". Monthly Notices of the Royal Astronomical Society.
3. (December 2015). "Origin and Evolution of the Cometary Reservoirs". Space Science Reviews.
4. (May 2017). "Visible spectra of (474640) 2004 VN112-2013 RF98 with OSIRIS at the 10.4 m GTC: evidence for binary dissociation near aphelion among the extreme trans-Neptunian objects". [[Monthly Notices of the Royal Astronomical Society: Letters]].
5. (1 November 2017). "Binary stripping as a plausible origin of correlated pairs of extreme trans-Neptunian objects". [[Astrophysics and Space Science]].