Battle for the planet: the authors withdrew their discovery of a planet in a system of three stars

(ORDO NEWS) — In 2016, an international team of scientists presented the first image of the planet in the triple system HD 131399 and published an article about it in the famous journal Nature. They retracted their article yesterday.

Battle for the planet the authors withdrew their discovery of a planet in a system of three stars 1Scientists have disproved the existence of a planet in the HD 131399 system. In this illustration, the supposed orbit of the planet is indicated in red, and the orbits of stars in blue

Even twenty years ago, astronomers doubted that planets could exist in systems with several stars. It was not clear how they could form in such unstable gravitational conditions, and then hold on and not fly out of the system. Everything changed when planets began to be found around triple stars.

In 2005, a Caltech scientist supposedly found a planet in the triple system HD 188753 . In his conclusions, he relied on calculations of the gravitational interaction of stars. At that time, astronomers found only 161 exoplanet candidates, so the discovery caused active discussion.

The results of the study were published in Nature . But in 2007, an independent group of astronomers made new observations, and the existence of the planet was not confirmed . Nevertheless, the number of exoplanet candidates continued to grow, and thanks to new telescopes, measurements became more and more accurate.

By 2016, scientists had confirmed the existence of thousands of exoplanets, but only a few could be seen directly, and not about gravitational interaction with stars. And then one fine day, a study was published in the journal Science with a picture of the planet in the triple system.

A team of astronomers, predominantly from the University of Arizona, was able to use the adaptive optics of the VLT telescope to detect the planet in the triple system HD 131399 and even get the spectrum of its atmosphere.

According to the authors’ calculations, the planet HD 131399Ab was four times more massive than Jupiter and orbited one of the three stars in the system.

At that time, it was one of the smallest and coldest known exoplanets. But, despite its stable orbit, scientists could not understand how HD 131399Ab could form or migrate to such a position.

A year later, another international team of scientists presented evidence that HD 131399Ab was probably not a planet. A distant object, possibly a dwarf star, has been captured by the Arizona group, according to new measurements.

This object is moving unusually fast, and its movement simply coincided with the movement of the triple system. They published the results of the refuting measurements in The Astronomical Journal.

Battle for the planet the authors withdrew their discovery of a planet in a system of three stars 2Composite image of the “planet” HD 131399Ab in the triple system HD 131399 . The image of the “planet” was taken by the SPHERE instrument of the VLT telescope

Of course, the authors of the picture decided to listen to criticism. It was decided to recheck the measurement results and this time to observe the movement of HD 131399 longer . Multiple observations took quite a long time, but made it possible to see the triple system in motion.

Scientists have found “a clear difference in parallax between the ‘planet’ and HD 131399 “. That is, their apparent position in the sky changed in different ways, which means that the objects are at different distances from the Earth. The “planet” turned out to be a distant object, and the scientists withdrew their paper.

Note that today exoplanets in triple systems are no longer surprising, but invariably attract the attention of scientists. There are still many questions about the formation and migration of planets in such gravitationally unstable systems.

In 2018, a small team of astronomers analyzed the then-discovered exoplanets in triple systems. An article with the results was published in the journal Astronomy and Astrophysics.

Scientists counted 32 triple systems with planets: 29 planets revolved around a remote single star, two around one of the stars in a pair, one around a pair of stars, and not a single planet revolved around the entire triple. Such a planet was found in 2021.

Battle for the planet the authors withdrew their discovery of a planet in a system of three stars 3The ALMA image on the left shows gaps in the protoplanetary disk of the GW Orionis system. In the SPHERE image on the right – the central region with a curved inner ring. The dark spot near the center is the shadow of this ring

In the young triple system GW Orionis , astronomers have discovered gaps in the protoplanetary disk. Usually such gaps are considered a clear sign of the formation of planets, but in the case of a triple system, scientists have doubts.

The unusual behavior of the protoplanetary disk could be provoked by the stars themselves, although the authors considered this unlikely.

They decided to check using a complex computer model. And the simulations have shown that the movement of stars is indeed not capable of creating such gaps in the disk. The presence of the planet turned out to be the most suitable explanation.

According to astronomers, 40-50% of star systems are binary, and about 20% are composed of three or more stars. Despite difficult gravitational conditions, scientists believe that systems with three or more stars account for about 2.5% of exoplanets in the universe.

The search for such objects and the interpretation of observational data is a complex process that requires constant rechecking of the results and the exclusion of even unlikely explanations. Therefore, admitting mistakes is an important part of the path to a more complete understanding of the physics of our universe.


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