Boiling 'baby bubble' where stars are born comes into view

A dramatic new image of a cosmic gas bubble reveals never-before-seen details of this birthplace of stars.

The bubble surrounds the Westerlund 2 star cluster, one of the brightest star-forming regions in the Milky Way. Westerlund 2 is about 20,000 light-years from Earth, and it hasn't been observed in high resolution until now. The new image shows that the star cluster is surrounded by a single bubble of gas, not two as previously hypothesized, and that it's likely to keep birthing stars well into the future.

"When massive stars form, they blow off much stronger ejections of protons, electrons and atoms of heavy metal, compared to our sun," study lead author Maitraiyee Tiwari, a postdoctoral associate in astronomy at the University of Maryland, said in a statement. "These ejections are called stellar winds, and extreme stellar winds are capable of blowing and shaping bubbles in the surrounding clouds of cold, dense gas. We observed just such a bubble centered around the brightest cluster of stars in this region of the galaxy, and we were able to measure its radius, mass and the speed at which it is expanding."