The impressive rho Ophiuchi cloud is one of the heavenly meeting points for astronomers in search of young stars. Located 540 light-years away in the constellation of Ophiucus, in the celestial equator, this dusty region is the nest of more than one hundred newborn stars.
About this image:
Three of the most massive young stars in this stellar nursery are easy to find in this image: one in the centre of the right-hand-side border; a second one in the middle of a comet-shaped nebula in the lower-right of the image; and finally, one in the middle of the small nebula close to the centre-right. Other point-like sources are also young stars and 'protostars' - stars that are still 'growing' by 'sucking in' gas from the cloud.
In the dust surrounding the newborn stars there are plenty of small carbonaceous grains. The exact nature of these grains is still a matter of debate. The young stars heat these grains and make them radiate infrared light (seen in the image as extended halos).
The colour image was constructed from a 7.7 micron infrared exposure (shown as blue), and a 14.5 micron infrared exposure (shown as red). The green colour is a combination of the blue and red exposures.
Further analysis of these data can be found in the paper "ISOCAM mapping of the Rho Ophiuchi main cloud" by Abergel et al., Astronomy and Astrophysics (A&A), 315, L329, (1996).