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The origin of a dwarf planet living in our solar system was a subject of debate for several years among astronomers. They now seem to have settled it. Ceres, a dwarf planet in the asteroid belt, has widespread ammonium deposits, and till now experts believed that its frozen form led to the creation of Ceres. But, ammonium is only stable in the outer solar system, indicating that Ceres formed outside our solar system and was slowly sucked in.

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New research has revealed that it is not true and Ceres was born in the asteroid belt itself. 

You might recall Ceres from the TV show "Expanse", in which the so-called 'belters' are based on this dwarf planet. The show has humans colonising the asteroid belt to mine the space rocks. 

Ceres has gained fame in the real world as well because of the doubts over its origin. It has a diameter of around 960 kilometres, is the biggest body between Mars and Jupiter in the belt and boasts an extremely complex and varied geology.

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A research team led by the Max Planck Institute for Solar System Research in Göttingen studied data from NASA's Dawn space probe and has found ammonium-rich deposits in the Consus crater. The discovery has shed new light on the birth of Ceres.

Dawn probe studied Ceres and noticed that it changed and evolved over many billions of years. It also found widespread ammonium deposits on the surface of Ceres. The team noted in the new study that it likely witnessed unique cryovolcanism until recently, which probably continued even today. 

There are light-coloured, whitish salt deposits in several impact craters. The Consus crater has emerged as the main mystery point where the deposits could indicate ammonium-rich material that has reached the surface from the depths of the dwarf planet owing to volcanism on Ceres.

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Researchers say that a brine seeped to the surface from a liquid layer between the mantle and crust over many billions of years, leading to the deposits.

After studying images and measurement data from the Consus crater in extreme detail, the team found material that was yellowish. It now believes that the presence of ammonium does not necessarily indicate an origin in the outer solar system, and there is a high chance that Ceres formed where it is orbiting today.

Consus crater on Ceres

Consus crater, located in Ceres' southern hemisphere, has a diameter of around 64 kilometres. It has a circumferential crater wall that rises about 4.5 kilometres above the crater floor. It contains inside it another smaller crater covering an area of about 15 kilometres by eleven kilometres.

The surface of Ceres is covered with ammonium-rich minerals. Earlier studies showed that these minerals form only through contact with ammonium ice, outside our solar system. As it nears the sun, it evaporates quickly. Ceres was therefore believed to have formed at the edge of the solar system.

But now, by establishing a connection between ammonium and the salty brine from Ceres' interior, researchers say that Ceres could be native to the asteroid belt.

 The research is published in the Journal of Geophysical Research: Planets.