Finding alien worlds in distant solar systems is a delicate task.
Astronomers’ instruments have come a long way since the first extrasolar planet Discoveries made in the 1990s, but the pursuit remains uphill: Finding tiny objects hundreds of light-years away, far outnumbered by their host stars. It should come as no surprise that, at times, discoveries of exoplanets are just a fluke.
This is the fate of the alleged planet HD 131399 Ab, which scientists once thought Three suns. When astronomers tried to look at the planet again, they found that it was actually something completely different and far in the background masquerading as an exoplanet. Now, the astronomers who originally discovered the planet are holding back their discovery.
The star system HD 131399 is located 350 light years from Earth in the constellation Centaurus. The star system consists of three stars: a white main star of type A about twice the mass of our sun, around which astronomers believe HD 131399 Ab orbits, and two smaller companions.
Scientists first announced The so-called discovery of HD 131399 Ab about six years ago. The newly discovered world the size of Jupiter got a fair amount of attention at the time, thanks in part to the novelty of a world with three suns. From the astronomers’ point of view, the discovery was interesting because it was imaged directly: Instead of seeing the planet as a speck of darkness or the oscillation of motion in its main star, the scientists observed it directly using their telescopes.
But as the years went by and astronomers tried to verify the system, they did Found That something wasn’t quite right. In particular, the scientists analyzed how different the objects are, and how well they move against the stellar background as seen at different points in Earth’s orbit. This analysis by independent astronomers found that the putative planet and star system are not equidistant from Land; Subsequent measurements by the planet’s original explorers confirmed this.
In other words, what scientists thought was a planet was actually something very fast moving in the background, several light-years from Earth far from the HD 131399 system.
“It must be a very red star – maybe a red giant, maybe even a star with a disk.” Kevin Wagner, an astronomer at the University of Arizona and one of the potential discoverers of HD 131399 Ab, told Space.com. He noted that the red color would make the star deceptively look like a planet.
In addition, this distant star appears to be moving at an abnormal speed, and thus appears to match a much closer star system. This discrepancy suggests that some phenomena gave the star a boost – it may have been expelled from its host system or had a close encounter with another, scientists believe.
“Each of these events would be rare on their own,” Wagner told Space.com. “The combination of these two low-probability properties of the background object is what led us to misclassify it as a planet.”
Wagner said he’s not aware of any other cases in which a red star or fast-moving object has been confused with a closer planet — but, as the HD 131399 Ab episode shows, the possibility certainly exists.
The search is described in paper Published Friday (April 15) in the journal Science.
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