Dysnomia, officially named (136199) Eris I Dysnomia, is a dwarf planetEris Is also the second largest dwarf planet satellite in the solar system, second only toCharon 。In 2005, American astronomerMichael Brown Formosa was discovered at Keck Observatory and temporarily named S/2005 (2003 UBthree hundred and thirteen) 1。In September 2006, this celestial body wasInternational Astronomical UnionIt was officially named Dysnomia after one of the daughters of Eris (the goddess of discord) in Greek mythology.[1]
With an estimated diameter of 700 ± 115 km (25% - 35% of the diameter of Eris), Eris is one of the 12 largest objects in the outer Neptune region.[2]
In 2005, the Keck Telescope in Hawaiiadaptive optics The team used the new laser guide star adaptive optics system toKuiper beltCelestial objects are observed as follows:Pluto（Pluto）、2005 FY9（Bird God Star，Makemake）、2003 EL61（Haumea , Haumea) and 2003 UBthree hundred and thirteen（Eris , Eris). In the observation results on September 10, they found a satellite orbiting 2003 UBthree hundred and thirteenRun, and then compile it as "S/2005 (2003 UB313) 1".Because 2003 UBthree hundred and thirteenIts nickname is "Xena" (the heroine of the American TV series "Xena: Princess Warrior"), so this satellite was also nicknamed "Gabrielle" (the assistant of the heroine Sina in the play).[3-4]
name
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DiscovererMichael Brown (Mike Brown) chose the name Dysnomia for Formosa.As the daughter of Eris, Dysnomia conforms to the established satellite naming model related to the parent planet gods (for example, the four major moons of JupiterJupiterWhile Saturn's moons followgod of agricultureNamed after Titan).In addition, Dysnomia's Greek Δ νσ ν μμαα literally translates into English as "lawlessness", echoing Lucy Lawless, the actress who plays Xena in Xena: Princess of the Warrior on TV.Although Brown pointed out that this connection was accidental, it was nicknamed "Xena" and "Gabrielle" before obtaining the official names of Geshin and Gesei.[5]
The main reason for taking this name is that it is similar to the name of Brown's wife Diane, following the pattern established by Pluto.The first two letters of Pluto's English name arePercival Lowell Acronym for Percival Lowell, Percival Lowell is the discoverer of PlutoClyde William Tombaugh(Clyde Tombaugh) is the founder of the observatory where he works and is also the person who inspires people to look for "Planet X".James Christy discovered Charon, and his wife Charlene's nickname, Char, added the Greek ending on.(Christie doesn't know that the name Charon is a figure in Greek mythology.) Similarly, the initials of Dysnomia are the same as Brown's wife Diane,[6]Brown used the nickname "Dy"/ˈ da ɪ/for Li Weiyi, with the same pronunciation as his wife's nickname Di.Therefore, Brown pronounced his full name/da ɪ s ˈ no ʊ mi ə/with a long "y" sound.[7]
physical characteristics
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The diameter of Formula 1 is estimated to be 700 ± 115 km, and the albedo is 0.04+0.02 − 0.01.This estimate was obtained by using the radiation observations of Alma Observatory in the submillimeter spectral region.[8]The same research proposed a wide range of possible satellite mass. The system mass ratio calculated according to its actual density is 37:1 to 115:1 (the mass calculated based on the minimum density of 0.8 g/cm3 is about 0.143 × 1021 kg, and if the density is the same as Eris, the mass is 0.437 × 1021 kg).Although the shape of Poseidon is not clear, astronomers believe that it is spherical due to its large size, which is larger than the three smallest ellipsoidal satellites, Saturn and Uranus（Enceladus、Tianwei FiveandEnceladus)。
In the image found by him, in the K-band, Formosa is about 60 times weaker (or 4.43 magnitude) than Formosa,[9-10]Later, it was observed with the Hubble Space Telescope that Eris is 500 times weaker than Eris in the visible light band.This indicates that Formosa has an unusual dark surface with a very red spectrum.[11]The diameter of Eripos indicates that it is a fairly large outer Neptune object.[12]Of the known dwarf planets, only Pluto is larger than Formosa.
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combinationKeck Observatory andHubble Space TelescopeAccording to Kepler's law of motion of the third planet, the orbit of Poseidon I is used to determine the mass of Poseidon.The average orbital distance between Eripos and Eris is about 37300 km (23200 miles), and the calculated orbital period is 15.786 days, or about half a month.[13]This shows that Eris is 1.27 times the mass of Pluto.[14-15]The extended observation of the Hubble Space Telescope shows that Eris has a nearly circular orbit near Eris, and the orbit eccentricity is low, 0.0062 ± 0.0010.In the orbit of Eripos I, due to the slightly eccentric orbit, the distance between Eripos and Eripos is 462 ± 105 kilometers (287 ± 65 miles).[13]The dynamic simulation of Io shows that, regardless of its density, its orbit should be completely rounded through the tidal interaction with Io in the time range of 5-17 million years.The current non-zero eccentricity of Formosa indicates that its orbit is disturbed, which may be due to the oblate shape of Formosa or the existence of another satellite of Formosa.[13]According to the Hubble observation data from 2005 to 2018, the calculated inclination of the orbit of Formosa I to the heliocentric orbit of Formosa is about 78 °.Since the inclination is less than 90 °, the orbit of Formosa 1 is advancing relative to the orbit of Formosa.By 2239, Eris and Eris will enter a period of mutual influence, when the orbital plane of Eris will align with the sun, so that Eris and Eris will appear alternately.[13]
formation
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Astronomers found that there are satellites in the six brightest Kuiper Belt objects;Only about one in ten of the other darker members of the Kuiper Belt objects have satellites.One explanation is that in the past, large Kuiper Belt objects (thousands of meters in diameter) often collided with each other, resulting in a large amount of material being thrown out, which eventually slowly combined into a satellite.This is very similar to the mechanism that the moon was formed in the early solar system when the earth encountered a huge impact.[11]
