Английская Википедия:2018 VG18

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Шаблон:Mp is a distant trans-Neptunian object that was discovered well beyond Шаблон:Convert from the Sun. It was first observed on 10 November 2018 by astronomers Scott Sheppard, David Tholen, and Chad Trujillo during a search for distant trans-Neptunian objects whose orbits might be gravitationally influenced by the hypothetical Planet Nine. They announced their discovery on 17 December 2018 and nicknamed the object "Farout" to emphasize its distance from the Sun.

Шаблон:Mp is the second-most distant natural object ever observed in the Solar System, after the trans-Neptunian object Шаблон:Mpl (132 AU) discovered by the same team in January 2018.Шаблон:Efn Шаблон:As of the object is at an observed distance of Шаблон:Convert from the Sun, more than three times the observed distance of the dwarf planet Pluto. Шаблон:Mp is not close to being the object with the most distant orbit on average, as its orbital semi-major axis is estimated to be only about 81 AU. For comparison, the semi-major axis of the planetoid and possible dwarf planet 90377 Sedna is about 500 AU.

Observations of Шаблон:Mp show that it appears pinkish in color, indicative of an ice-rich surface.

Discovery

Файл:2018 VG18 discovery image.gif

Animation of two discovery images taken by the 8.2-meter Subaru telescope on 10 November 2018. The moving dot in the center is Шаблон:Mp at magnitude 24.6.

Шаблон:Mp was discovered by astronomers Scott Sheppard, David Tholen, and Chad Trujillo at the Mauna Kea Observatory in Hawaii on 10 November 2018. The discovery formed part of their search for distant trans-Neptunian objects (TNOs) with orbits that may be gravitationally perturbed by the hypothesized Planet Nine. The search team had been involved in the discoveries of several other distant TNOs, including the sednoids Шаблон:Mpl and 541132 Leleākūhonua. Шаблон:Mp was first identified as a faint object slowly moving in two images taken with the 8.2-meter Subaru Telescope on the night of 10 November 2018. At the time of discovery, Шаблон:Mp was located in the constellation Taurus,Шаблон:Efn at a very faint apparent magnitude of 24.6, approaching the lowest detectable magnitude limit for most telescopes.

Шаблон:Mp's low on-sky motion and brightness indicated that it is very distant, which prompted additional follow-up observations to constrain its orbit and distance. The object was reobserved in December 2018 by Sheppard at the Las Campanas Observatory, with observation times spanning ten days. However, its orbit remained with a significant uncertainty due to its short observation arc. Nonetheless, the discovery of Шаблон:Mp along with a preliminary orbit solution was formally announced in a Minor Planet Electronic Circular issued by the Minor Planet Center on 17 December 2018.

Since the discovery announcement, Шаблон:Mp has been periodically observed by Sheppard at the Las Campanas and Mauna Kea observatories. Additional observations were also made at the Roque de los Muchachos Observatory in November 2019 and January 2020. Шаблон:As of, Шаблон:Mp has been observed for over five oppositions, with an observation arc of 16 years (5,900 days). Several precovery observations of Шаблон:Mp have been identified in images taken by the Cerro Tololo Observatory's Dark Energy Camera on 11 March 2015 and 16 January 2017, as well as images taken by the Canada-France-Hawaii Telescope and Subaru Telescope in November 2003 and September 2005, respectively.

Nomenclature

Upon the announcement of Шаблон:Mp's discovery, the discoverers nicknamed the object "Farout" for its distant location from the Sun, and particularly because it was the farthest known TNO observed at the time. On the same day, the object was formally given the provisional designation Шаблон:Mp by the Minor Planet Center. The provisional designation indicates the object's discovery date, with the first letter representing the first half of November and the succeeding letter and numbers indicating that it is the 457th object discovered during that half-month.Шаблон:Efn The object has not yet been assigned an official minor planet number by the Minor Planet Center due to its short observation arc and orbital uncertainty. Шаблон:Mp is expected to receive a minor planet number once it has been observed for over at least four oppositions, which would take several years. Once it receives a minor planet number, the object will be eligible for naming by its discoverers.

Orbit and classification

Шаблон:See also Шаблон:Mp is the second-most distant observed Solar System object from the Sun and is the first object discovered while beyond 100 astronomical units (AU), overtaking the dwarf planet Шаблон:Dp (96 AU) in observed distance. Шаблон:As of Шаблон:Mp's distance from the Sun is Шаблон:Convert, more than three times the observed distance of Pluto from the Sun (34 AU during 2018). For comparison, the distances of the Pioneer 10 and Voyager 2 space probes were approximately 128 AU and 126 AU in 2021, respectively. At its nominal distance, Шаблон:Mp is thought to be close to the heliopause, the boundary where the Sun's solar wind is stopped by the interstellar medium at around 120 AU. The new orbit determination indicates that this object is currently very close to aphelion which it should reach in mid-2067, and that it is a member of the scattered disc.

At the time of discovery on 10 November 2018, Шаблон:Mp's distance from the Sun was 123.4 AU, and has since moved 0.2 AU from the Sun Шаблон:As of. As it is approaching aphelion, Шаблон:Mp is receding from the Sun at a rate of 0.06 AU per year, or Шаблон:Cvt. Шаблон:Mp was the farthest TNO known until February 2019, when Шаблон:Mpl (nicknamed "FarFarOut") was discovered at about 132 AU by the same team led by Sheppard. While Шаблон:Mp and Шаблон:Mp are among the farthest Solar System objects observable, some near-parabolic comets are much further from the Sun. For example, Caesar's Comet (C/-43 K1) is over 800 AU from the Sun while Comet Donati (C/1858 L1) is over 145 AU from the Sun Шаблон:As of.

Шаблон:Mp's average orbital distance from the Sun is approximately 81 AU, taking approximately 738 years to complete one full orbit. With an orbital eccentricity of about 0.53, it follows a highly elongated orbit, varying in distance from 38.3 AU at perihelion to 125.0 AU at aphelion. Its orbit is inclined to the ecliptic plane by about 24 .3 degrees, with its aphelion oriented below the ecliptic. At perihelion, Шаблон:Mp approaches close to Neptune's orbit without crossing it, having a minimum orbit intersection distance of approximately 8 AU. Because Шаблон:Mp approaches Neptune at close proximity, its orbit has likely been perturbed and scattered by Neptune; thus, it falls into the category of scattered-disc objects. Шаблон:Mp last passed perihelion in the late 17th century.

Файл:Extreme transneptunian object orbits with 2018 VG18.png

Orbit diagram of several extreme trans-Neptunian objects, with scattered-disc objects Шаблон:Dp and Шаблон:Mp shown for scale.

While Шаблон:Mp is one of the most distant objects observed, it does not have the largest orbital semi-major axis. For comparison, the semi-major axis of the planetoid 90377 Sedna is about 500 AU. In an extreme case, the scattered-disc object Шаблон:Mpl has a semi-major axis around 1,400 AU, though its distance from the Sun Шаблон:As of is about 64 AU, approximately half Шаблон:Mp's distance from the Sun in that year.

Шаблон:Mp was discovered in a particular region of the sky where other extreme TNOs have been found, suggesting that its orbit may be similar to those of extreme TNOs, which characteristically have distant and highly elongated orbits that may have resulted from the gravitational influence of the hypothetical Planet Nine. Шаблон:Mp's nominal orbit appears to be anti-aligned with Sedna; the longitude of pericenter of Шаблон:Mp's orbit is oriented about 193 degrees from Sedna's orbit.Шаблон:Efn

Physical characteristics

The size of Шаблон:Mp is unmeasured, though it is likely large enough to be a possible dwarf planet, based on its intrinsic brightness or absolute magnitude. Based on its apparent brightness and large distance, Шаблон:Mp's absolute magnitude is estimated to be in the range of 3.4–4.5. According to the Minor Planet Center, it is the ninth intrinsically brightest scattered-disc object.

The albedo (reflectivity) of Шаблон:Mp has not been measured nor constrained, thus its diameter could not be calculated with certainty. Assuming that the albedo of Шаблон:Mp is within the range of 0.10–0.25, its diameter should be around Шаблон:Cvt. This size range is considered to be large enough such that the body can collapse into a spheroidal shape, and thus be a dwarf planet. Astronomer Michael Brown considers Шаблон:Mp to be highly likely a dwarf planet, based on his size estimate of Шаблон:Cvt calculated from an albedo of 0.12 and an absolute magnitude of 3.9. Unless the composition of Шаблон:Mp is predominantly rocky, Brown considers it very likely that Шаблон:Mp has attained a spheroidal shape through self-gravity. Astronomer Gonzalo Tancredi estimates that the minimum diameters for a body to undergo hydrostatic equilibrium are around Шаблон:Cvt and Шаблон:Cvt, for predominantly icy and rocky compositions, respectively. If the composition of Шаблон:Mp is similar to the former case, the object would be considered a dwarf planet under Tancredi's criterion.

Observations of Шаблон:Mp with the Magellan-Baade telescope show that the object is pinkish in color. The pinkish color of Шаблон:Mp is generally attributed to the presence of ice on its surface, since other ice-rich TNOs display a similar color. Apart from its color, the spectrum and surface composition of Шаблон:Mp have not yet been measured in detail and will require further observations.

See also

• Шаблон:Mpl, nicknamed "FarFarOut" by its discoverers
• List of Solar System objects by greatest aphelion
• List of Solar System objects most distant from the Sun
• List of trans-Neptunian objects

External links

• Discovered: The Most-Distant Solar System Object Ever Observed – Carnegie Science press release
• Farout Images Шаблон:Webarchive – Discovery images of Шаблон:Mp taken with the Subaru Telescope
• It’s the Solar System's Most Distant Object. Astronomers Named It Farout. – The New York Times article by Kenneth Chang
• Meet your very, *very* distant solar system neighbor 2018 VG18 – Bad Astronomy blog by Phil Plait
• List Of Centaurs and Scattered-Disk Objects – Minor Planet Center
• Шаблон:JPL small body