Researchers discover unusual triple constellation in the Kuiper Belt
After 17 years of observation, researchers are certain that what they thought was a group of two celestial bodies is actually a constellation of three.
Artistic representation of Altjira
(Image: NASA)
Researchers have discovered an unusual system in the Kuiper Belt: 148780 Altjira consists of three celestial bodies. It was not easy to tell them apart.
148780 Altjira is around 6 billion kilometers away from Earth and consists of three Kuiper Belt Objects (KBO), each around 200 kilometers in size.
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Altjira was discovered with the Hubble Space Telescope. On the images, however, it appeared as a system of two: they showed what appeared to be two objects around 7,600 kilometers apart. It was only through further observations of the movements of the KBOs that the researchers discovered that one of the two was actually two. However, they are so close together that it is difficult to tell them apart from such a great distance.
Hubble's resolution was not enough
“With such small and distant objects, the distance between the two inner members of the system on the Hubble camera is only a fraction of a pixel, so you have to resort to non-imaging methods to find out that they are a group of three,” said Maia Nelsen, lead author of the study.
This took time: Nelsen and her team observed the system for a total of 17 years with Hubble and the W. M. Keck Observatory in Hawaii, and found that the orbit of the outer object changed over time. A triple system seemed to be the best explanation.
The question is how Altjira was formed. The theory is that Altjira was formed from the gravitational collapse of matter in the disk around the sun. Systems with several stars also form in this way. “The universe is full of three-body systems, including the closest star to Earth, Alpha Centauri, and we find that the Kuiper Belt is no exception,” Nelsen said.
Only Pluto is well studied
The Kuiper Belt is located beyond Neptune and consists of remnants from the early days of the solar system, i.e., 4.5 billion years ago. The number of objects is not known. There are said to be around 70,000 KBOs with a diameter of more than 100 kilometers. So far, only the dwarf planet Pluto, the largest KBO, and the double system Arrokoth, have been well researched by the New Horizons probe.
Around 40 binary objects in the Kuiper Belt are known to date. Two of them could also be a triple constellation. Altjira could therefore not be such a special feature.
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The study on Altjira has been published in The Planetary Science Journal. Nelsen and her team want to continue observing the object. “Altjira has entered an eclipsing period in which the outer object passes in front of the central object. This will last for ten years and provide scientists with a great opportunity to learn more about the system,” said the researcher.
(wpl)
