ESA Science & Technology - W3 star-forming complex

This three-colour image of the W3 giant molecular cloud combines Herschel bands at 70 μm (blue), 160 μm (green) and 250 μm (red). The image spans about 2x2 degrees. North is up and east is to the left.

W3 is an enormous stellar nursery about 6200 light-years away in the Perseus Arm, one of the Milky Way galaxy's main spiral arms, that hosts both low- and high-mass star formation. In this image, the low-mass protostars are seen as tiny yellow dots embedded in cool red filaments, while the highest-mass stars – with greater than eight times the mass of our Sun – emit intense radiation, heating up the gas and dust around them and appearing here in blue. W3 Main and W3 (OH) contain the most recent high-mass star formation.