Kelly McSweeney

Feb 21st 2022

GW Orionis: A First-of-Its-Kind Star System in the Orion Constellation


For casual stargazers, one of the most easily recognizable observable constellations is Orion. This constellation is visible high in the night sky during winter. Observers might notice a bright star, or the famous Orion’s “belt” of three bright blue stars, but an odd feature has astronomers taking a closer look.

Recently, they observed a funky star system in the constellation called GW Orionis, about 1,300 light-years away from Earth. GW Orionis has three warped, misaligned rings, and it appears to be the first of its kind among the star systems that have been observed to this day.

What’s So Strange About GW Orionis?

In May 2020, Jiaqing Bi, Nienke van der Marel and their colleagues published a study in the Astrophysical Journal Letters which suggested that a planet could be the reason GW Orionis has such a strange misalignment of rings. “To our knowledge, its outermost ring is the largest dust ring ever found in protoplanetary disks,” they wrote.

Researchers observed the odd rings for the first time in 2017. “We were surprised to see the strong misalignment of the inner ring,” said Bi in a National Radio Astronomy Observatory (NRAO) announcement. “But the strange warp in the disk is confirmed by a twisted pattern that ALMA (Atacama Large Millimeter/submillimeter Array) measured in the gas of the disk.”

In September 2020, astrophysicist Stefan Kraus and 32 colleagues published a study in Science that reveals new details about an odd trio of stars in Orion. The authors explain that young stars are surrounded by a circumstellar disk made of gas and dust. Scientists theorize that planets can form from the materials in these disks.

Kraus stated in the NRAO announcement, “In our images, we see the shadow of the inner ring on the outer disk. At the same time, ALMA allowed us to measure the precise shape of the ring that casts the shadow. Combining this information allows us to derive the three-dimensional orientation of the misaligned ring and of the warped disk surface.”

In a straightforward solar system like ours, planets orbit a single star like the sun. But GW Orionis is more complicated. Two of the stars are orbiting each other, while a third star orbits them hundreds of millions of miles away. This appears to be creating an odd gravitational situation that is warping the disk.

The authors write, “Our images show an eccentric ring that is misaligned with the orbital planes and the outer disk. The ring casts shadows on a strongly warped intermediate region of the disk. If planets can form within the warped disk, disk tearing could provide a mechanism for forming wide-separation planets on oblique orbits.”

Gaining Deeper Insights From Space

Popular Science reports that the system’s inner ring has enough dust to build 30 Earths. The new study, which is the culmination of 11 years of work, provides new insight into how planets are formed, especially in unusual orbits. According to the NRAO, if future studies find an exotic planet in GW Orionis, it would be the first planet ever observed to orbit three stars, and it would “possess a very unusual orbit.”

In the latest Orion studies, astronomers used instruments on the Very Large Telescope (VLT) array and ALMA, both of which are located in the Chilean desert, and Georgia State University’s Center for High Angular Resolution Astronomy (CHARA) telescope array in California.

Along with ground-based observatories, the Hubble Space Telescope has been taking awe-inspiring images from space since 1990. And soon, the James Webb Space Telescope, an orbiting infrared observatory that’s 100 times more powerful than Hubble, will be positioned even deeper in space — 1.5 million kilometers from Earth. This will allow astronomers to peer even deeper into space to discover previously unknown details of funky star systems and much more.

If astronomers have been able to find fascinating systems like GW Orionis with the existing tools so far, the next generation of space exploration is bound to be even more exciting.

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