MADRID, 14 Jun. (EUROPA PRESS) –
A cosmic event captured with the SOFIA airborne observatory and the ALMA radio telescope has provided new evidence that traveling stars can form binary systems.
From a far out view, the star-forming cloud L483 appears normal. But as a team of astrophysicists led by Northwestern University got closer and closer, things got weirder and weirder.
When the researchers took a closer look at the cloud, they noticed that its magnetic field was curiously twisted. And then, as they examined a newborn star within the cloud, they saw a hidden star, hidden behind her.
“He’s the star’s brother, basically,” he said. it’s a statement Erin Cox is a postdoctoral associate at Northwestern’s Center for Interdisciplinary Research and Exploration in Astrophysics (CIERA), who led the new study. “We think these stars formed far apart and one got closer to the other to form a binary. As the star traveled closer to its sister, changed the dynamics of the cloud to twist its magnetic field.”
The new findings provide insights into binary star formation and how magnetic fields influence the early stages of star development.
Cox is presenting this research at the 240th meeting of the American Astronomical Society (AAS) in Pasadena, California. The Astrophysical Journal will also publish the study.
Stellar nurseries are wild and wonderful places. As dense clouds of gas and dust collapse to form stars, they launch streams of stellar material at hypersonic speeds. A magnetic field surrounding a star-forming cloud is usually parallel to these outflows. When Cox and his collaborators looked at the large-scale L483 cloud, they found just that. The magnetic field matched this typical profile.
But then astrophysicists decided to take a closer look with NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), and that’s when things got weird. The magnetic field was not, in fact, parallel to the outflows of newborn stars. Instead, the field was twisted at an angle of 45 degrees to the outflows.
“At first, it matched what the theory predicts,” Cox said. “If you have a magnetized collapse, then the magnetic field is controlling how the star is forming. We hope to see this parallel. But theory may say one thing and observations may say another.”
Although more observations are needed, Cox believes that a previously hidden sister star may be responsible for the twisted field. Using SOFIA, the astrophysics team detected a newborn star forming inside an envelope of material. But following further examination with radio telescopes on the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the researchers detected the second star, sharing the same stellar envelope.
“These stars are still young and still forming,” Cox said. “The stellar envelope is what provides the material to form stars. It’s similar to rolling a snowball on snow to make it bigger and bigger. Young stars are ‘rolling’ in material to build up mass.”
At roughly the same distance between our sun and Pluto, the two young stars form a binary system. Astrophysicists now agree that binaries can form when star-forming clouds are large enough to produce two stars or when the disk around a young star partially collapses to form a second star.
But for the twin stars in L483, Cox suspects something unusual is at play.
“There’s newer work that suggests it’s possible for two stars to form far away from each other, and then one star gets closer together to form a binary,” Cox said. “We think that’s what’s happening here. We don’t know why one star is moving towards another, but we think the moving star changed the dynamics of the system to twist the magnetic field“.
Cox believes this new work might ultimately provide new insights into how binary stars and the planets that orbit them form. Most people are familiar with the iconic scene from “Star Wars,” in which Luke Skywalker gazes longingly at the binary stars orbiting his home planet of Tatooine. Scientists now know that this scenario is not just science fiction; planets orbiting binary stars might potentially be habitable worlds.
