Astronomers have “pushed” the boundaries of the Kuiper belt

New Horizons, flying through the outer edge of the Kuiper Belt, detected higher dust densities at a distance where theoretical models would suggest it would decline. Scientists explained this effect by saying that the boundaries of the study area may be wider than previously thought.

The Kuiper Belt is part of the outer region of the Solar System, which is somewhat similar to the asteroid belt, but is almost 20 times wider and 200 times more massive. These two belts are inhabited by small bodies formed from material left over from the formation of the Solar System. But these bodies have different compositions.

Unlike asteroid belt objects, which are mostly composed of rocks and metals, Kuiper belt objects are mainly composed of ices, which contain methane, ammonia and water. Moreover, some of these bodies are dwarf planets, under the surface of which oceans of liquid water are hidden.

Until recently, it was believed that the boundaries of the Kuiper belt lie in the range from 30 to 55 astronomical units. But new data from NASA's New Horizons probe, which is flying through the area, indicates it could be much wider, extending to 80 astronomical units or even further. A group of American planetary scientists led by Alex Doner from the University of Colorado at Boulder spoke about this in their article published in The Astrophysical Journal Letters.

Kuiper belt objects are considered the main source of dust in the outer solar system. Theoretical models show that the population of bodies and dust density should decrease towards the outer edge of the belt, which is about 50 astronomical units from the Sun.

Doner and his colleagues analyzed data collected by the New Horizons probe's SDC (Venetia Burney Student Dust Counter) detector. This tool searches for dust particles, records them, and determines their mass and speed. Scientists found that starting at 42 astronomical units from the Sun, the density of dust particles did not decrease, which contradicted the indications of dust distribution models, but began to “jump” up to 55 astronomical units from the Sun. In other words, the dust flux density at the “edge” of the Kuiper Belt turned out to be higher than previously thought.

What do the research results say? Dust in the Kuiper Belt results from the collision of objects and bombardment of their surfaces with interstellar dust particles. Doner suggested that solar radiation pressure could push dust generated in the Kuiper belt beyond 42 astronomical units, and the belt itself could be much wider. It likely extends billions of kilometers further than is commonly believed in the scientific community.

Doner explained that his team is now using ground-based telescopes to find other possible explanations for the reasons for such high dust flux densities.

The New Horizons space probe was launched into space in 2006 to study Pluto and its moon Charon. Nine years later, the device approached the dwarf planet and for the first time showed that it is a cold world with plains covered with nitrogen ice and mountain ranges more than three kilometers high. This indicates that at least 100 million years ago Pluto was geologically active. Based on the photographs and other information sent, scientists concluded that under the surface of Pluto there could once have been an ancient ocean of liquid water (it may still be there today).

In September 2023, NASA announced that it had extended the New Horizons mission. According to experts, the station will have enough fuel and energy to operate until 2040. It is planned that by this time the device will have covered a distance of 100 astronomical units and may have discovered a transition zone where interstellar dust particles begin to dominate interplanetary dust particles.

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