Astronomer William Herschel discovered the planet Uranus and its two moons 230 years ago. Using the Herschel Space Observatory, a team of astronomers led by Örs H. Detre of the Max Planck Institute for Astronomy has now succeeded in determining the physical characteristics of Uranus’ five major moons. Infrared radiation, measured by the Sun heating their surface, indicates that these moons are similar to dwarf planets such as Pluto. The team has developed a new analytical method that separates dim signals from satellites near Uranus, which is more than a thousand light years away. The study was published in the journal Today Astronomy and astronomy.
To explore the outer regions of the Solar System, Space probes Cassini-Huygens and New Horizons, like Voyager 1 and 2, were sent on long voyages. A German-Hungarian research team led by Örs H. Detre of the Max Planck Institute for Astronomy (MPAA) in Heidelberg has shown that interesting results can be achieved through remote observation using appropriate technology and ingenuity.
Scientists used data from the Herschel Space Observatory deployed between 2009 and 2013 and were significantly involved in the development and operation of the MPA. The observations of this telescope were very sharp compared to its predecessors, which included a similar spectral range. It is named after astronomer William Herschel Infrared radiation A few years ago, he discovered the planet Uranus and its two moons (Titania and Oberon), and now examined them in more detail along with three other moons (Miranda, Ariel, and Umbriel).
“In fact, we made observations to measure the impact of very bright infrared sources such as Uranus on the camera detector,” explains Co-author Alric Klass, who led the working group for the PACS camera at the Herschel Space Observatory at MPA. Pictures taken by them. “We accidentally found the moons as extra nodes in the planet’s brightest signal.” Developed under the auspices of the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, the PACS camera was sensitive to wavelengths of 70 to 160 160m. It is more than a hundred times the wavelength of visible light. As a result, images from the Hubble Space Telescope of the same size are a hundred times sharper.
Cold objects in this spectral range are very bright, meaning that Uranus and its five major moons – heated by the Sun, reach temperatures ranging from 60 to 80 K (–213 to –193 C).
“Observation time was a stroke of luck,” explains Thomas Mുള്ളller from MPE. The axis of rotation of Uranus and the orbital heads of the moons are abnormally inclined into their orbits around the Sun. Although Uranus has been orbiting the Sun for several decades, the Sun mainly shines in the northern or southern hemisphere. “During the observation, this position was very favorable, and the equatorial regions benefited from solar radiation, enabling us to measure how much heat is retained on the surface as it moves toward the night due to rotation. The moon. It taught us a lot about the nature of matter, “explains Mർller, who calculated the models of this study, from which he derived the thermal and physical properties of the moons.
When Uranus passed Voyager 2 space probe in 1986, it was not in favor of the galaxy. Scientific instruments can only capture the south polar regions of Uranus and the moons.
Mുള്ളller found that these surfaces store heat unexpectedly and cool relatively slowly. Astronomers know this characteristic from compact objects with rough, icy surfaces. This is why scientists speculate that these moons are Pluto Homia, a celestial body similar to the dwarf planets at the edge of the Solar System. Independent studies of some external and irregular uranium satellites based on observations with PACS / Herschel indicate that they have different thermal properties. These moons show the characteristics of small and loose transneptunian objects located in an area outside the planet Neptune. “It would also be suitable for ulations who are concerned about the origin of random satellites,” Mുള്ളller added. “Because of their turbulent orbits, the uranium system only captured them at a later date.”
However, the five major satellites were largely ignored. In particular, very bright objects such as Uranus create strong crustal objects in PACS / Herschel data, which cause infrared light in images to be distributed over large areas. This is especially noticeable when observing dim skies. This is most evident with Uranus. “Faint moons between 500 and 7,400 times farther away from Uranus, they’s merge with similar luminous asteroids. Only the brightest moons, Titania and Oberon, are slightly different from the surrounding luminosities,” says the Concoli Observatory at the Cobodapest Observatory.
This accidental discovery prompted Hrs HH Dere to make the moons more visible so that their brightness could be measured reliably. “In similar cases, such as the search for exoplanets, we use chronographs to obscure their bright central star,” Ditre explains. “Herschel did not have such a device. Instead, we took advantage of the excellent photometric stability of the PACS device.” Based on this stability, he developed a method that would allow Uranus to be removed from the data after estimating the exact positions of the moons during observation. “We were all amazed when four satellites appeared clearly in the pictures, and we were even able to find the smallest and most intimate Miranda of the five largest uranium satellites,” Ditre concludes.
“The results show that we do not always need extensive planetary space missions to gain new insights into the solar system,” said Hendrik Lins, co-author of the MPA. “Also, the new algorithm can be applied to more observations collected in the electronic data archives of the European Space Agency (ESA). Who knows what might still be waiting for us there?”
. H. Ditre et al. Herschel-PACS photometry of the five major moons of Uranus, Astronomy and astronomy (2020). DOI: 10.1051 / 0004-6361 / 202037625
Max Planck Society
Source: Uranium satellites in new light (September 14, 2020) retrieved September 14, 2020 from https://phys.org/news/2020-09-uranian-moons.html
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