New dwarf planet found at the edge of the solar system
A dwarf planet the size of Belarus has been found beyond Pluto's orbit. The cold object was discovered using a system of radio telescopes recently installed in Chile.
Astronomers have discovered a large object on the outskirts of the solar system, which is most likely a dwarf planet, it has already given its own name - DeeDee, or Distant Dwarf, dwarf planet. The discovery of this object was announced at the end of 2016, but almost nothing was known about its nature.
It was possible to learn more about its structure with the help of a powerful tool - the ALMA (Atacama Large Millimeter Array) radio telescope complex in Chile.
These 66 parabolic antennas, commissioned in 2013, have become one of the most powerful radio astronomy instruments in the world. They form a radio interferometer, which makes it possible to construct images of distant objects with high spatial resolution.
DeeDe, which was named 2014 UZ224 when discovered, is three times farther from the Sun than Pluto, and is the next largest trans-Neptunian object after the dwarf planet Eris. According to scientists' calculations, just beyond the orbit of Neptune there may be tens of thousands of similar objects that are just waiting to be discovered.
New observations at ALMA allowed for the first time to accurately determine the size of a trans-Neptunian object - 635 km, which is two-thirds of the size of Ceres, a dwarf planet orbiting in the main asteroid belt between the orbits of Jupiter and Mars. With this size, the discovered body must have a spherical shape, and this is a necessary criterion for the International Astronomical Union to classify it as a dwarf planet. “Far beyond Pluto's orbit is an area surprisingly rich in planetary bodies. Some are quite small, while others can be compared with Pluto and be further larger, - said David Gerdes of the University of Michigan, author of the publication in Astrophysical Journal Letters.
DiDee's image from the ALMA radio telescope
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“Because they are so distant and dim, it's incredibly difficult to even capture them, let alone examine them in detail. ALMA, however, is uniquely capable of letting us know the delightful features of this distant world."
DeeDe is currently 92 astronomical units from the Sun (1 AU is equal to the distance from the Earth to the Sun), in such an orbit the period of complete revolution around the Sun is more than 1100 years.
And the light from this object reaches the Earth in 13 hours.
Comparison of the sizes of DeeDe with the territory of the USA, the sizes of the Moon and Pluto
Gerdes and colleagues reported the discovery of this body in October 2016, the discovery was made using a 4-meter optical telescope at the Cerro Tololo Observatory in Chile as part of the Dark Energy Survey to study dark energy in the universe.
This survey gave astronomers a huge number of pictures of the sky, which made it possible to search for new distant objects in the solar system. Initially, more than 1.1 billion such candidates were obtained by analyzing images. Most of them turned out to be distant background stars or even galaxies. However, a small number of them managed to notice their own motions and prove that these are trans-Neptunian objects.
DeeDe was spotted in 12 separate images, the analysis of which gave only the distance to the object and the parameters of its orbit. Its size remained unknown: DeDee could be a small asteroid with high brightness or, conversely, a large object with a low albedo (reflection index).
ALMA radio telescopes (41 "saucer" participated in the observations) managed to catch a weak radiation flux from this body in the millimeter range, the magnitude of which is directly proportional to its size. “We calculated that this object must be extremely cold, only 30 degrees above absolute zero,”explained Gerdes.
Scientists have found that DeDe's surface reflects only 13% of the sunlight falling on it, about the same as dry soil. According to astronomers, such objects were formed in the early stages of the formation of the solar system, and the technique used in the discovery can help in the discovery of the notorious ninth planet of the solar system, for which astronomers have been hunting since January 2016.
Pavel Kotlyar