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Discovered in 2004, Haumea is a dwarf planet located beyond the orbit of Pluto in a region of the solar system called Kuiper Belt. Pluto was demoted from the full-fledged category of planets in 2006 because of the discovery of Haumea and other dwarf planets.
Haumea was officially recognized as a dwarf planet in 2008. Its ellipsoidal shape resembles that of the ball used in rugby or American football. He has two moons and a ring. Because of its ring, Haumea is part of a group of solar system objects including the planets Saturn, Uranus, Neptune and Jupiter, as well as the asteroids Chariklo and Chiron, which revolve around Jupiter and Neptune.
The Haumea ring has never been observed directly. Its existence was inferred in 2017 by an international group of astronomers who took detailed measurements of the fluctuations of light when Haumea occulted (passed in front) a star. In the space, an occultation occurs when one object passes in front of another from the point of view of the observer.
"The starlight was observed from Earth while the star was obscured by Haumea.Its brightness decreased when Haumea exceeded it, allowing astronomers to obtain information. on Haumea's form, "said Othon Cabo Winter, an ordinary professor in Sao Paulo. Engineering School of the State University (FE-UNESP) in Guaratingueta, Brazil.
"The star's light is also dimmed when the ring is passed in front of it, thus allowing them to obtain information about the ring."
Researchers who discovered the ring in 2017 suggested that its orbit around Haumea was very close to the 1: 3 resonance region, meaning that ring particles make a turn every three time.
A new study by Winter, Tais Ribeiro and Gabriel Borderes Motta, belonging to the group of orbital dynamics and planetology of UNESP, shows that a degree of eccentricity would be required for this resonance to act on the particles of the ring.
According to Winter, the fact that the ring is narrow and virtually circular prevents the action of resonance. However, the group has identified a specific type of stable, almost circular periodic orbit, in the same region as the Haumea ring. A periodic orbit is an orbit that repeats itself over time.
"Our study is not observational – we have not observed the ring directly – no one has ever done it," Winter said. The reason is that the ring is very thin and far too far to be seen by the astronomical observatories here on Earth. The average distance between Haumea and the Sun is 43 times the distance between the Earth and the Sun.
"Our study is entirely computational.On the basis of simulations using the data available on Haumea and the ring, subject to Newton 's law of gravitation, which describes the motions of the planets, we concluded that the. Ring was not found in this region of space due to: 1: 3 resonance but due to a stable periodic orbital family, "Winter said.
In an article published in the Monthly Notices of the Royal Astronomical Society, researchers explore the dynamics of individual particles in the region where the ring is located.
The underlying research was part of the thematic project "On the relevance of small organisms in orbital dynamics" funded by the Sao Paulo Research Foundation (FAPESP) and supported by the Brazilian Federal Government through CAPES, the research council in higher education, and the CNPq National Council for Scientific and Technological Development.
"The main objective of our research was to identify the structure of the Haumea ring in terms of location and size of stable regions.We also wanted to find the reason for it. The existence of the ring We were particularly interested in understanding the dynamic structure associated with its 1: 3 resonance, Winter said.
Stable regions
The researchers used the Poincaré cutting surface technique to analyze the dynamics of the region in which the ring is located. By simulating the particle trajectories in the region, they generated computer graphics (sections) displaying stable areas represented by islands (closed curves) and unstable areas represented by irregularly distributed dots.
The islands of stability found due to the 1: 3 resonance had very eccentric orbits, more than they would be compatible with the ring (narrow and circular).
"On the other hand, we detected islands of stability in the same area, but with low eccentricity trajectories compatible with the ring.These islands were identified as being due to a family of owls. periodic orbits, "Winter said.
Haumea has a diameter of 1,456 km, less than half the diameter of Mars, and an oval shape that makes it twice as long as it is wide. It takes 284 years to walk around the sun. The dwarf planet is so far away and the sunlight reaches it so low that its surface temperature is minus 223 ° C.
The moons of Haumea, Namaka and Hi iaka, were detected by the giant lenses of one of the observatories located at the top of the dormant volcano Mauna Kea, Hawaii. The dwarf planet owes its name to the Hawaiian goddess of fertility and childbirth, and her moons at the origin of Haumea's daughters. It is thought that they resulted from a collision between the dwarf planet and another body.
Haumea rotates in less than four hours and rotates faster than any other known balance body in the solar system. This may have to do with a violent past.
Astronomers think that originally, Haumea looked a lot like Pluto when the solar system was formed. Billions of years ago, a large object could have collided with Haumea, expelling most of its surface ice and spinning it much faster than other dwarf planets.
Research Document
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