Hubble Finds New Planet That Could Change Planet Formation Theories

The Hubble Space Telescope has uncovered evidence of an alien planet forming strangely far from its host star. Astronomers have said the discovery could challenge the prevailing theory about how planets form.

Researchers with the Hubble program discovered a large gap in the planet-forming debris disk that surrounds TW Hydrae, a red dwarf star.

The gap was likely caused by a still unseen infant exoplanet between six and 28 times the size of Earth. The new planet is about 7.5 billion miles away from its host star. That equates to about twice the distance Pluto is from our sun.

But the new planet’s location far away from the sun it orbits poses problems for the current theory about planet formation. The theory suggests that worlds will grow slowly over tens of millions of years. The farther away the planet is from its sun, the slower it should grow.

But the numbers don’t add up. TX Hydrae is about eight million years old, but the planet would have taken longer than that to form, according to the current theory.

Because of the new planet found by Hubble, an alternative idea is suggesting that some planets can form within a thousand years if pieces of the planet-forming debris disk become gravitationally unstable and collapse on themselves. However, researchers still aren’t sure how such a low-mass planet can form so fast.


Astronomers hope that further study of TW Hydrae and its newly-formed exoplanet will help them figure out what is going on. They hope to discover if the system is unique or if the theory needs to change. Lead study author John Debes, who works with the Space Telescope Science Institute in Baltimore, Maryland, released a statement saying:

“If we can actually confirm that there’s a planet there, we can connect its characteristics to measurements of the gap properties. That might add to planet formation theories as to how you can actually form a planet very far out.”

Along with the super fast formation of TW Hydrae’s exoplanet, the Atacama Large Millimeter Array in Chile was able to see that the system doesn’t have grains larger than a gain of sand more than 5.5 billion miles away from the star. This means that the planetary dust that created the exoplanet was smaller than the sand on our beaches.

[Image via NASA/JPL-Caltech]