ne of our joys and frustrations as researchers comes from the universe’s habit of finding multiple ways to accomplish the same thing. Did galaxies form in one large collapse of stuff into one large galaxy or through the build-up of lots of small stuff into a large galaxy? Honestly, it depends on the galaxy.

As we look about and work to understand star formation here and beyond, we see a variety of behaviors. In another new study, this time in the Astronomical Journal, researchers led by Peter Zeidler used the Hubble Space Telescope to study how stars form in the outskirts of a massive cluster in the nearby Small Magellanic Cloud and then spiral in toward the center of the cluster. This pattern of formation and migration is dictated by factors like angular momentum, friction, and good ol’ gravitational interactions. Understanding the physics is actually straightforward. What was hard was getting this data. Their Hubble data was taken over eleven years and allows the stars changing positions in the sky to be measured. Combined with Doppler shift measurements from the VLT, which measure speed like a cop’s radar guns, this team measured the stars’ 3-D movements and found a spiral of motion not otherwise seen in a static picture of this system.

This same kind of spiraling behavior may exist in other star-forming clusters, and I hope more long-term studies will help us understand if what we see happening out there is also happening here.

There are always more questions. Always.

More Information

NASA press release

“The Internal Line-of-Sight Kinematics of NGC 346: The Rotation of the Core Region,” Peter Zeidler, Elena Sabbi, and Antonella Nota, 2022 September 8, The Astrophysical Journal