Seeing baby stars at every stage of their formation

Stars form from the collapse of dense clouds of gas and dust, which makes it very hard for astronomers to watch the process unfold. Recently the ALMA telescope has revealed a treasure trove of embryonic stars in the Taurus Molecular Cloud, illuminating how baby stars are born.

The Atacama Millimeter/submillimeter Array (ALMA) in the Atacama Desert is the world’s premiere radio telescope, capable of detecting some of the most exquisite and detailed processes and formations in the universe. And now it’s taken some pictures of baby stars.

The not-yet-stars are in a vast complex known as the Taurus Molecular Cloud only 430 light-years away from Earth. The cloud is a massive cosmic nursery, currently popping out a batch of hundreds of new stars.

Each star forms from the collapse of a pocket of gas and dust, pinched off from the much vaster cloud complex. At the beginning of this process, each pocket is relatively easy to observe, since they’re so large. But as star formation continues, the pockets become smaller and smoother, making observations harder.

That’s why a team of astronomers used only a central core section of the ALMA array in a recent study of the Taurus Molecular Cloud. The full array is much better at capturing fine details, but the pockets surrounding baby stars are relatively featureless, so there aren’t a lot of fine details to capture. Additionally, the wide separation of the dishes in the ALMA array make it best suited to zooming way in, whereas with only the core elements, the team could capture a much wider picture.

All in all, the team captured over 40 pockets of star formation, including 32 in a stage too early to have a protostar. Only 12 of those 32 were also emitting radio waves, indicating that they were beginning to form an internal structure (a key step on the road to stardom).

In addition to the 32 starless cores, the team found 9 pockets with protostars already embedded in them, including signs of what’s called a “first hydrostatic core”. This occurs when the heat released from the collapse of the cloud is enough to stabilize it from crunching down further. Eventually gravity will win and turn it into a real star, but this short-lived stage is truly a lucky find.