October 5, 2000: The Hubble telescope has peered deep into a neighboring galaxy to reveal details of the formation of new stars. Hubble's target was a newborn star cluster within the Small Magellanic Cloud, a small satellite galaxy of our Milky Way. The picture shows young, brilliant stars cradled within a nebula, or glowing cloud of gas, cataloged as N 81.
The massive, recently formed stars inside N 81 are losing material at a high rate, sending out strong stellar winds (a stream of charged particles) and shock waves of material and hollowing out a cocoon within the surrounding nebula. The two most luminous stars, seen in the Hubble image as a very close pair near the center of N 81, emit a flood of ultraviolet radiation, causing the nebula to glow through fluorescence. Outside the hot, glowing gas is cooler material, consisting of hydrogen molecules and dust. Normally this material is invisible, but some of it can be seen in silhouette against the background of the nebula, appearing as long dust lanes and a small, dark, elliptical-shaped knot. Astronomers believe that the young stars have formed from this cold matter through gravitational contraction.