The location of the possible planet. Image: NASA.
Using space telescopes at NASA and ESA, researchers have found what they believe is evidence of a planet transiting a star in the Whirlpool galaxy.
In a major breakthrough, astronomers have discovered what might be a new planet that exists outside of the Milky Way. The planet was detected by researchers using NASA’s Chandra x-ray and the ESA’s XMM-Newton x-ray space telescopes.
The hunt for exoplanets beyond the Milky Way has proved difficult for astronomers so far, and this new finding marks a significant development. The planet is thought to be the size of Saturn, but its existence has yet to be fully verified. It was found orbiting a star located in the galaxy Messier 51 (M51). The galaxy is also called the Whirlpool galaxy because of its distinctive spiral profile.
According to a blogpost published on the ESA’s website following the discovery, identifying planets and stars is difficult even for advanced space telescopes. This is because the light from another galaxy is paced into a very small area on the sky making it almost impossible for telescopes to even find stars, let alone large planets. Finding exoplanets outside of our galaxy is even more unlikely.
Now, the challenge of verifying the planet’s existence begins. If its existence was confirmed, it could widen the scope of future planetary searches significantly. An exoplanet in M51 would be about 28m light years away, meaning it would be thousands of times further away than those in the Milky Way.
“We are trying to open up a whole new arena for finding other worlds by searching for planet candidates at x-ray wavelengths, a strategy that makes it possible to discover them in other galaxies,” said Rosanne Di Stefano of the Center for Astrophysics at Harvard & Smithsonian in the US, who led the study.
The study’s findings were published in the Nature Astronomy journal on 25 October. Di Stefano and her team have already discounted a number of possible explanations as to what the discovery may be. They have ruled out the possibility that the planet might have been a cloud of dust or a star, as it is too large and has a well-defined surface.
It may prove challenging for the team to get another look at the planet due to its long orbit time of 70 years.
“We can only say with confidence that it doesn’t fit any of our other explanations,” Di Stefano said.
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