Small objects seen floating in space

Not only are stars born here but smaller objects as well

By BBC News Online science editor Dr David Whitehouse

Japan's Subaru Telescope has taken a sharp image of a star-forming region and discovered many small planet-like objects with masses less than that of ordinary stars.

The starbirth region, designated S106, is at a distance of approximately 2000 light-years from the Earth. A young massive star called IRS4 (Infrared Source 4) lies at its centre.

The "hourglass" appearance of S106 is thought to be the result of the way material is flowing outwards from the young star. A huge disk of gas and dust surrounding the star produces the constriction seen at the centre of the region.

The Subaru telescope

Hydrogen gas produces the blue light seen in the inner part of the cloud. The red region seen towards the edge of the cloud is caused by light reflected from dust particles.

Because the image, taken in the infra-red region of the spectrum, is extremely sharp, subtle details can be seen including differences in colour and structure between the various parts of the nebula.

A study of the image has revealed hundreds of faint young objects around IRS4 and scattered throughout the surrounding nebula. They are too small to sustain the nuclear burning of hydrogen gas that causes a normal star to shine. The lightest and faintest objects discovered have an estimated mass of only a few times that of Jupiter.

A group of astronomers from the National Astronomical Observatory of Japan and the University of Tokyo have observed similar small objects elsewhere in the sky, in the nearby star-forming region in the constellation of Taurus and Orion.

While such objects could be called "planets" if they orbited a star, most astronomers consider the term is not appropriate for them. Many call them "floating small objects."