Getting to grips with The Blob

Hubble's view of The Blob: In such places stars are born

By BBC News Online science editor Dr David Whitehouse

The Hubble Space Telescope has peered deep into a neighbouring galaxy to reveal details of the formation of new stars.

Hubble looked at a young star cluster within the Small Magellanic Cloud, an outrigger galaxy to our own. The new images show young, brilliant stars embedded in a glowing cloud of gas, catalogued as N81.

Outside the hot, glowing gas is cooler material consisting of hydrogen and dust. Normally this material is invisible, but some of it can be seen in silhouette as long dust lanes and knots.

It is believed that the young stars have formed from this cold matter through gravitational contraction.

Turbulent conditions

Because little detail can be seen in N81 from ground-based telescopes, astronomers call it The Blob.

Astronomers were not sure if just one or a few hot stars were embedded in the cloud, or if it was a stellar nursery containing a large number of less massive stars.

Hubble's high-resolution imaging shows the latter to be the case, revealing that numerous young, white-hot stars are contained within N81.

This crucial information bears strongly on theories of star formation, and N81 offers a singular opportunity for a close-up look at the turbulent conditions accompanying the birth of massive stars.

Heavy elements

The brightest stars in the cluster have a luminosity equal to 300,000 stars like our own Sun.

Astronomers are especially keen to study star formation in the Small Magellanic Cloud, because its chemical composition is different from that of the Milky Way.

All of the chemical elements, other than hydrogen and helium, have only about one-tenth the abundances seen in our own galaxy.

The study of N81 provides a chance to study star formation that occurred in very distant galaxies, before nuclear reactions inside stars had synthesised the elements heavier than helium.