What happens in a star-forming galaxy does not stay in a star-forming galaxy. Powerful outflows from newborn stars can energize space well beyond the main boundaries of a galaxy.
Sanchayeeta Borthakur at Johns Hopkins University in Baltimore, Maryland, and her colleagues used the Hubble Space Telescope to probe 20 nearby galaxies. Each galaxy had gone through a burst of star formation within the past few hundred million years.
The authors found that winds flowing from the newborn stars ionize gas particles some 200 kiloparsecs from the galactic centres. This is the first observation of such long-distance changes.
The outflows may modify galactic material in ways that suppress future star growth.