Astronomers may have discovered first planet to orbit 3 stars

A picture of GW Orionis, a triple-star system that has a mysterious gap between its dust rings and a mysterious star called Triple Star System. UNLV astronomers believe there is a large planet within the gap. This would make it the first known planet to orbit three stars. The left image, provided by the Atacama Large Millimeter/submillimeter Array (ALMA) telescope, shows the discs ringed structure, with the innermost ring separated from the rest of the disc. The shadow of the innermost circle on the rest of disc can be seen in the right-side image. UNLV astronomers used ALMA observations to create a complete model of the star systems. Credit: ALMA (ESO/NAOJ/NRAO), ESO/Exeter/Kraus et al.
Researchers from UNLV and their colleagues might have discovered the first planet known to orbit three stars.

Unlike the solar system that consists only of one star, half of star systems (like GW Ori) where astronomers discovered this new phenomenon are made up of multiple stars that are gravitationally bound together.

However, no known planet with a three-star orbit has been found. Perhaps until now.


Using observations from the powerful Atacama Large Millimeter/submillimeter Array (ALMA) telescope, UNLV astronomers analyzed the three observed dust rings around the three stars, which are critical to forming planets.

They found a large, but puzzling, hole in the circumtriple disc.

Researchers looked into many possible origins of the gap, including the possibility that it was caused by gravitational torque between the three stars. After building a detailed model of GW Ori they discovered that the most likely explanation for the disc's space is the existence of one or more large planets. These planets are Jupiter-like in their nature. Jeremy Smallwood is the lead author. He is a UNLV recent Ph.D. student in astronomy. Gas giants are often the first planets that form within a starsystem. The next step is the formation of terrestrial planets such as Earth and Mars.

Although the planet cannot be seen directly, the discovery made in September in the Monthly Notices of the Royal Astronomical Society suggests that it is the first circumtriple-planet ever found. The ALMA telescope will continue to make observations in the future, which could be used to confirm the phenomenon.

Smallwood stated that "it's really exciting because this makes the theory about planet formation really robust." It could indicate that planet formation may be more active than we thought. That's pretty cool.

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