Astronomer's new guide to the galaxy

Largest map of cold dust revealed

Astronomers have unveiled an unprecedented new atlas of the inner regions of the Milky Way, our home galaxy, peppered with thousands of previously undiscovered dense knots of cold cosmic dust — the potential birthplaces of new stars.

This new guide for astronomers, known as the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) shows the Milky Way in submillimeter-wavelength light (between infrared light and radio waves). Images of the cosmos at these wavelengths are vital for studying the birthplaces of new stars and the structure of the crowded galactic core.

“ATLASGAL gives us a new look at the Milky Way. Not only will it help us investigate how massive stars form, but it will also give us an overview of the larger-scale structure of our galaxy”, said Frederic Schuller from the Max Planck Institute for Radio Astronomy, leader of the ATLASGAL team.
The Universe is relatively unexplored at submillimeter wavelengths, as extremely dry atmospheric conditions and advanced detector technology are required for such observations.

The interstellar medium — the material between the stars — is composed of gas and grains of cosmic dust, rather like fine sand or soot. However, the gas is mostly hydrogen and relatively difficult to detect, so astronomers often search for these dense regions by looking for the faint heat glow of the cosmic dust grains.

Submillimeter light allows astronomers to see these dust clouds shining, even though they obscure our view of the Universe at visible light wavelengths. Accordingly, the ATLASGAL map includes the denser central regions of our galaxy, in the direction of the constellation of Sagittarius — home to a supermassive black hole — that are otherwise hidden behind a dark shroud of dust clouds.

The newly released map also reveals thousands of dense dust clumps, many never seen before, which mark the future birthplaces of massive stars. The clumps are typically a couple of light-years in size, and have masses of between ten and a few thousand times the mass of our Sun. In addition, ATLASGAL has captured images of beautiful filamentary structures and bubbles in the interstellar medium, blown by supernovae and the winds of bright stars.

ESO