Where do new stars form in galaxies?

May 24, 2019

Kruijssen_NGC300_750x500 An optical image of the spiral galaxy NGC 300 with molecular clouds shown in blue. An analysis of star formation in these clouds show that the first stars that form quickly disperse the cloud, stifling further star formation. (Image courtesy of Diederik Kruijssen & Nature)

Spiral galaxies like our own Milky Way are studded with cold clouds of hydrogen gas and dust, like chocolate chips in a loaded Toll House cookie.

Astronomers have long focused on these so-called molecular clouds, suspecting that they are hotspots for star formation. But are they?

After a thorough analysis of the molecular clouds in a nearby spiral galaxy, an international team of astronomers has found that, while star formation starts up rapidly in these clouds, the newly formed stars quickly disperse the cloud – in as little as a few million years – stopping further star formation. So while star formation in cold molecular clouds is fast, it’s highly inefficient.

The findings by a collaboration led by Diederik Kruijssen from Heidelberg University will help astronomers understand where and when stars form in galaxies, which in turn determines how galaxies change over their lifetimes.

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