A mysterious stellar nursery is breaking the model of how star systems form

“At first, it matched what theory predicts."
Grant Currin
Spitzer Space Telescope (left), and the Bok globule analyzed in the new study (right)1, 2

An infant star is forcing astronomers to update their theories on how the universe works.

Researchers were taken by surprise while looking at a stellar nursery roughly 650 light-years from Earth. They were interested in a cloud of gas and dust so massive that its gravity is causing the object to collapse into itself, forming a new star.

“At first, it matched what theory predicts,” said astronomer Erin Cox, who led the study of what astronomers call a Bok globule, in an embargoed release shared with IE. Cox and her colleagues will present the research Tuesday at the annual meeting of the American Astronomical Society.

The star looked normal at first, but when Cox and her team took a closer look, they realized the prevailing theory didn't explain what they saw.

A star causes a mismatch between matter and magnetism

Infant stars aren't quiet objects. As new, powerful telescopes have come online, researchers have discovered that young stars shoot powerful jets of starstuff at incredible speed. These "outflows" serve as release valves for stars that are using their gravitational force to acquire huge quantities of matter.  Ordinarily, a star's magnetic field is parallel to its outflows, meaning that it fires matter from its north and south poles. This is textbook astrophysics.

But researchers seem to have found an exception to the theory: When Cox and her team looked at the Bok globule using NASA’s SOFIA instrument, they saw that its magnetic field isn't aligned with the outflows. It was a big surprise because there is a close physical relationship between a young star's outflows and its magnet field. “If you have a magnetized collapse, then the magnetic field is controlling how the star is forming," Cox said, in the release.

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"We expect to see this parallelism. But theory can say one thing, and observations can say another," added Cox.

Another observation solves the mystery — and sparks new questions

An explanation for the mismatch might have come from an array of telescopes in the Chilean desert. Data from those radio telescopes show that the Boc globule isn't alone. As it turns out, the stellar nursery is home to a second young star. “These stars are still young and still forming,” Cox said. “The stellar envelope is what supplies the material to form the stars. It’s similar to rolling a snowball in snow to make it bigger and bigger. The young stars are ‘rolling’ in material to build up mass," she said.

According to the current picture of star formation, systems that contain two (or more) stars form when the stellar envelope is especially big. They can also come into existence when the collection of matter orbiting one young star collapses, forming a secondary cloud that itself becomes a second star. Neither one of those processes would explain how the second star caused the Bok globule's outflows to misalign with its magnetic field, but an emerging theory that offers a third explanation for multi-star systems could point to an answer.

A third way for binary star systems to emerge?

"There is newer work that suggests it’s possible to have two stars form faraway from each other, and then one star moves in closer to form a binary,” Cox said. “We think that’s what is happening here." While the researchers' work is still far from complete, the math that underlies this new interpretation seems to explain the data that Cox and her team have reviewed.

"We don’t know why one star would move toward another one, but we think the moving star shifted the dynamics of the system to twist the magnetic field," Cox said. With newer, even more powerful instruments such as the James Webb Space Telescope coming online, researchers will soon learn more about this mysterious system.

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