Title: The Orion Nebula

Source: Hubble Space Telescope

Information: These HST images clearly distinguish the central star from the disk and show that stars in Orion that are the mass of our Sun and lower are likely to possess disks. Stars hotter than our Sun might destroy the dusty disks before they can agglomerate into planets, according to O'Dell. HST can see the disks because they are illuminated by the hottest stars in the Orion Nebula, and some of them are seen in silhouette against the bright nebula. However, some of these proplyds are bright enough to have been seen previously by ground-based optical and radio telescopes as stars. Their true nature was not recognized until the HST observations. One striking HST image shows a dark elliptical disk silhouetted against the bright background of the Orion nebula. "This object represents the most direct evidence uncovered to date for protoplanetary disks," says O'Dell. Hubble's resolution has allowed O'Dell to determine accurately the mass of the outer rim of the disk. It turns out to be at least several times the mass of our Earth. The entire disk is 53 billion miles across, or 7.5 times the diameter of our solar system. The central, reddish star is about one fifth the mass of our Sun. (Note: This image is pixellated because it is an extreme closeup of the best image of this subject available from the HST.)