The planet with three suns disappears

A group of astronomers announced in the summer of 2016 the discovery of a unique planet: a huge gaseous world four times larger than Jupiter.

It was so far from its star that a year there lasted more than five centuries.

It was also a planet of insulting youth: just 16 million years, nothing compared to the 4,500 million that the Earth has.

The new world was in the constellation Centaurus, 320 light-years from Earth.

It would be necessary to travel three centuries and 20 more years at the speed of light to reach it, something unthinkable for human ships.

But the most suggestive thing about this new planet was that its sky had three suns.

The largest was the star around which this gas giant orbited;

and the remaining two were gravitationally anchored to each other.

During half of the year – more than two terrestrial centuries – there were three suns in the sky of this planet, explained the authors of the finding, achieved with the brand new Sphere instrument of the Very Large Telescope (VLT), one of the largest optical instruments in the world. .

The finding was published in

possibly the most prestigious journal in world science.

The European Southern Observatory, owner of the VLT, announced in a press release that this planet was more exotic than Tatooine, the imaginary planet from the

which had two suns in its sky.

On Holy Thursday, astronomer Kevin Wagner of the University of Arizona (USA) and the rest of the team that made this discovery announced in the same magazine that they are withdrawing their original study for a very simple reason: that planet was never there.

A year after the supposed discovery, another team of astronomers pointed the same VLT instrument at the planet in question, called HD 131399Ab.

They also used the Keck telescope, in Hawaii (USA), and spent more hours observing it than the original team.

The results of their work were clear: the light signal from the supposed planet was actually a much more distant star that was behind the three suns studied.

In fact, they warned that if it were a planet, it would move so fast that it would inevitably reach the so-called escape velocity.

This means that it would circumvent the gravitational pull of its star and shoot off into space like rockets from Earth.

"It was a real blow," Wagner acknowledges to this newspaper.

“When we took out our study we were very sure.

The object's spectrum, brightness, and motion made it look entirely like a planet in a triple solar system.

And we calculated that the possibility that it was a false positive was very low, ”he argues.

In February of this year, Wagner published a new paper compiling several years of observations of the star that supposedly hosts HD 131399Ab.

“In our first observations the object seemed very aligned with the movement of its star, it was very consistent with a planet.

But as time passed and we looked more, we saw that this movement was more consistent with that of a star that was moving quite fast and was aligned with that of the main body.

We now think it is a red giant star [like the Sun when it dies in about 5 billion years], probably in combination with a disk around it that makes it even brighter in infrared light.

Hard or embarrassing as it may be, the case of the missing planet exemplifies how things should be done in science.

It is also an example of an evil well known to many scientists: the growing pressure to publish the results as soon as possible, and if possible with spectacular headlines.

"Planets with three suns are very normal," explains José Caballero, a specialist in exoplanets at the Center for Astrobiology in Madrid.

"The closest star system to Earth, Alpha Centauri, has three planets that see three suns, one red and closer and two yellow more distant," he explains.

What made this planet special was how far away its orbit was from the star, which was twice the distance from Pluto to the Sun. In 2006, Caballero described an object of this type very far from its star.

"Retracting is fine, or at least admitting that one was wrong when he had worse data," says the Spanish astronomer.

“The problem was that they rushed.

When they published it in 2016 they had only 11 months of observation.

By comparison, in my doctoral thesis ten years earlier we worked with twice as long time lines and with stars between 2 and 10 times closer, so we were up to 20 times more sensitive to the difference in motion between the investigated star and the object in the background," he details.

The time scale of human observations poses a huge challenge here, since we are dealing with very distant planets and with years that last centuries, with which only a small fraction of their orbit is observed.

"I would not have published it in 2016, I would have waited for more data, but this team is from the US and perhaps they had a lot of pressure to publish," continues Caballero.

“But in the end I will defend them.

we can say 'how badly they did it', but without risky proposals science does not advance and, after all, the data they had in 2016 was compatible with the scenario of the planet”.

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