Well-known star turns out to be not one star, but twins

Some regions and objects in the cosmos are favored targets for astronomers due to their proximity and the unique features they possess, like stellar nurseries or black holes. Occasionally, even these well-known objects unveil unexpected surprises, as happened recently with the star system WL20.


The Discovery of WL20S

Astronomers using the James Webb Space Telescope (JWST) made a startling revelation about a star in the WL20 region. Known as WL20S, this star was observed to be not a single star but a pair.

“What we discovered was absolutely wild,” said astronomer Mary Barsony. “We’ve known about star system WL20 for a long time. But what caught our attention is that one of the stars in the system appeared much younger than the rest. Using MIRI and ALMA together, we actually saw that this ONE star was TWO stars right next to each other. Each of these stars was surrounded by a disk, and each disc was emitting jets parallel to the other.”

The JWST’s MIRI (Mid-Infrared Instrument) and the ground-based ALMA (Atacama Large Millimeter/submillimeter Array) were instrumental in this discovery. Webb observed the jets of material from the stars, while ALMA provided detailed images of the disks of material around them.

Mike Ressler from NASA’s Jet Propulsion Laboratory highlighted the importance of using both telescopes together: “The power of these two telescopes together is really incredible. If we hadn’t seen that these were two stars, the ALMA results might have just looked like a single disk with a gap in the middle. Instead, we have new data about two stars that are clearly at a critical point in their lives, when the processes that formed them are petering out.”

The disks of material around each star could potentially be forming planets, while the jets are composed of streams of charged particles emitted from the poles of each star. The combination of Webb’s infrared capabilities and ALMA’s radio wavelength observations was crucial for making this discovery.

“It’s amazing that this region still has so much to teach us about the life cycle of stars,” said Ressler. “I’m thrilled to see what else Webb will reveal.”

The collaborative power of the JWST and ALMA continues to provide groundbreaking insights into our understanding of star formation and the complex processes that govern stellar systems.