One of the most violent and wondrous cosmic events is starburst, in which hundreds of millions of stars are born all at once. These are far rarer nowadays than they were in the early universe, but they do still happen... and the massive energy released during these periods can alter the future histories of entire galaxies.
That's the finding of new research from Hubble astronomers. Using the space telescope to study 20 nearby galaxies undergoing starburst activity, they discovered that the cosmic winds generated by starburst had effects that extended far beyond just the immediate vicinity of the newborn stars. The Hubble site explains:
They found that the winds accompanying these star formation processes were capable of ionizing gas up to 650,000 light-years from the galactic center — around twenty times further out than the visible size of the galaxy. This is the first direct observational evidence of local starbursts impacting the bulk of the gas around their host galaxy, and has important consequences for how that galaxy continues to evolve and form stars.
The starburst galaxies within the sample were seen to have large amounts of highly ionized gas in their halos — but the galaxies that were not undergoing a starburst did not. The team found that this ionization was caused by the energetic winds created alongside newly forming stars. This has consequences for the future of the galaxies hosting the starbursts. Galaxies grow by accreting gas from the space surrounding them, and converting this gas into stars. As these winds ionise the future fuel reservoir of gas in the galaxy’s envelope, the availability of cool gas falls — regulating any future star formation.
Image by ESA, NASA, L. Calçada.