Contents 1 Summary 2 File info 3 Individual images 4 Licensing

Summary

This image from NASA's Spitzer Space Telescope reveals the complex life cycle of young stars, from their dust-shrouded beginnings to their stellar debuts. The stellar nursery was spotted in a cosmic cloud sitting 21,000 light-years away in the Cepheus constellation.

A star is born when a dense patch gas and dust collapses inside a cosmic cloud. In the first million years of a star's life, it is hidden from visible-light view by the cloud that created it. Eventually as the star matures, its strong winds and radiation blow away surrounding material and the star fully reveals itself to the universe.

The first stages of stellar life are represented by the greenish yellow dot located in the center of the image (just to the right of the blue dot). Astronomers suspect that this source is less than a million years old because spectra of the region (right bottom graph) reveal a deep absorption feature due to silicate dust (crushed crystalline grains that are smaller than sand) indicating that the star is still deeply embedded inside the cosmic cloud that collapsed to form it. Wisps of green surrounding the star and its nearby environment illustrate the presence of hot hydrogen gas.

Above and to the left of the central greenish yellow dot, a large, bright pinkish dot reveals a more mature star on the verge of emerging from its natal cocoon. Although this star is still shrouded by its birth material, astronomers use Spitzer, a temperature-sensitive infrared telescope, to see the surrounding gas and dust that is being heated up by the star.

The region's oldest and fully exposed stars can be seen as bunches of blue specks located just left of the concave ridge. Energetic particles and ultraviolet photons from nearby star clusters etched this arc into the cloud by blowing away surrounding dust and gas.

Spectral observations of the ridge (right top graph) and reddish-white dot, or "mature star" (right middle graph), indicate the presence of carbon rich molecules called polycyclic aromatic hydrocarbons (PAHs), which are found on barbecue grills and in automobile exhaust on Earth.

The featured image is a four-channel false-color composite, where blue indicates emission at 3.6 microns, green corresponds to 4.5 microns, and red to 5.8 and 8.0 microns. The image was taken by Spitzer's Infrared Array Camera (IRAC). Spectra of the region were obtained with the telescope's Infrared Spectrometer (IRS) instrument

File info

Individual images

see https://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=sig06-021 High quality tif files also avaliable.

Licensing

Photo's description:

In this stunning picture of the giant galactic nebula NGC 3603, the crisp resolution of NASA's Hubble Space Telescope captures various stages of the life cycle of stars in one single view. To the upper left of center is the evolved blue supergiant called Sher 25. The star has a unique circumstellar ring of glowing gas that is a galactic twin to the famous ring around the supernova 1987A. The grayish-bluish color of the ring and the bipolar outflows (blobs to the upper right and lower left of the star) indicates the presence of processed (chemically enriched) material. Near the center of the view is a so-called starburst cluster dominated by young, hot Wolf-Rayet stars and early O-type stars. A torrent of ionizing radiation and fast stellar winds from these massive stars has blown a large cavity around the cluster. The most spectacular evidence for the interaction of ionizing radiation with cold molecular-hydrogen cloud material are the giant gaseous pillars to the right of the cluster. These pillars are sculptured by the same physical processes as the famous pillars Hubble photographed in the M16 Eagle Nebula. Dark clouds at the upper right are so-called Bok globules, which are probably in an earlier stage of star formation. To the lower left of the cluster are two compact, tadpole-shaped emission nebulae. Similar structures were found by Hubble in Orion, and have been interpreted as gas and dust evaporation from possibly protoplanetary disks (proplyds). This true-color picture was taken on March 5, 1999 with the Wide Field Planetary Camera 2.