Red and blue light are from regions of hydrogen gas heated by nearby stars, astronomers said. The green light on the left comes from glowing oxygen. The energy to illuminate the green light is supplied by a powerful stellar wind -- a stream of high-speed particles -- coming from a massive star just outside the image.

The white region in the center is a combination of all three emissions and indicates a core of hot, massive stars. The intense emission from these stars has carved a bowl-shaped cavity in the surrounding gas.

In the white region, the two bright areas, seen by astronomers as the eyes of the ghost, are named A1 (left) and A2 (right). They are very hot, glowing blobs of hydrogen and oxygen. The bubble in A1 is produced by the hot, intense radiation and powerful stellar wind from a single massive star. A2 has a more complex appearance due to the presence of more dust, and it contains several hidden, massive stars.

The massive stars in A1 and A2 must have formed within the last 10,000 years, since their natal gas shrouds are not yet disrupted by the powerful radiation of the newly born stars, researchers say.

This picture was composed from three filtered images obtained March 28, 2000, with Hubble's Wide Field Planetary Camera 2.

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