ISO observes young stars inside a nearby cloud

The small bright objects in this image from ISO, ESA's Infrared Space Observatory, are young stars at the relatively close astronomical distance of about 500 light-years. They are the nearest new-born stars, but they cannot be seen in visible light because the Rho Ophiuchi dark cloud obscures them totally, even from the Hubble Space Telescope. In 1983 ISO's predecessor, the IRAS infrared astronomical satellite, registered emissions from the young stars inside the Rho Ophiuchi dark cloud. With a shaper eye and unprecedented sensitivity, ISO now reveals this scene of young stars and dusty wisps much more clearly. Here, two images of the densest part of the dark cloud from ISO's camera ISOCAM are combined in a colour composite. Emissions at about 7 microns are tinted blue, while red is used for emissions from cooler regions at 15 microns. The scattered bright dots are new stars of moderate size, comparable in mass to the Sun. The bright fuzzy object, upwards and slightly to the right of centre, is a new massive star, much heavier that the Sun, still wrapped in the placental cloud from which it formed. A similar object appears partly veiled towards the bottom right of the picture. The conspicuous wisp right of centre is the interface between the dense cloud and the general interstellar medium. In a dark region near the centre of the picture the dust is so dense that even an infrared telescope can look no further into the murk. [Image Date: 12-06-97] [97.07.013-003]