The G305 star-forming complex

On 21 May ESA released an image which was obtained as part of Hi-GAL. Hi-GAL, the Hershel infrared Galactic Plane Survey, combines observations at three different wavelengths: 70 microns (blue), 160 microns (green), and 250 microns (red). Launched in 2009, Herschel operated for 4 years, in which it observed at far infra-red and sub-millimeter wavelengths, a spectral range allowing it to observe the glow of dust in gas clouds. This allowed investigation of the birth of stars, and to observe their early evolution.

The image is of the G305 star-forming complex: a stellar nursery. Cloudy and dusty places that shine brightly in infra-red light, stellar nurseries feature a number of bright, intricate gas clouds. These are heated by the infant stars in their midst, which stand out in the image as a blue tone, contrasting with the red-brownish colour of cooler regions.

Several star-formation sites dot the scene. The most striking ones, however, surround the dark, heart-shaped area in the top right. Hidden at the center of the dark region are WR48a, a massive star, and its two neighbors: stellar clusters Danks 1 and 2. They are relatively young: no older than a few million years. ESA mentions, as a comparison, that the Sun is around 4.6 billion years old. They play an important role, however, in triggering the formation of new stars. The strong solar winds and radiation from WR48a and the high-mass stars in the two clusters have pushed away the gas remnants from the cloud in which they originated. Swept aside, the gas now comes together at the edge of the heart-shaped bubble, forming new stars.

About 12.000 light-years away, G305 complex derives its name from its location: it is around 305º longitude in the plane of our Galaxy. It is visible in the night sky, a large interstellar cloud of dust, appearing in the constellation of Crux, the Southern Cross. It is near the prominent dark Coalsack Nebula, which shows up on in the Southern hemisphere against the bright, starry backdrop of the Milky Way.

The cloud-capp’d tow’rs, the gorgeous palaces, the solemn temples, the great globe itself, (…) We are such stuff as dreams are made on.