ESO Creates Mind-Boggling Map of the Galaxy

Astronomers and astrophysicists studying stellar nurseries – the places inside galaxies where conditions are perfect for the formation of new stars – and crowded galactic cores will soon have at their disposal a new survey of the skies, to use in assessing probabilities of where such places may exist. The new APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) study was created using the European Southern Observatory's (ESO) APEX telescope, located 5,100 meters high, on the Chajnantor plateau, in the Chilean Andes.

For this survey, APEX's operators decided to go with sub-millimeter wavelengths, an area of the electro-magnetic spectrum stretching between infrared light and radio waves. This interval is the most appropriate one for breaking through cosmic gas and dust, which usually conglomerate around stellar nurseries. Thus, these important structures become obscured from visible and near-ultraviolet wavelengths, which are not strong enough to penetrate them. The image that was created in the new study can be downloaded from this link (53Mb, 16,000-pixel resolution).

“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,” Max Planck Institute for Radio Astronomy expert Frederic Schuller, the leader of the ATLASGAL team, says. The reason why such sub-millimeter images were not available before is very simple – it takes extremely dry atmospheric conditions on Earth for this type of observations, as well as an advanced detector technology, which is, unfortunately, very rare.

“It's exciting to get our first look at ATLASGAL, and we will be increasing the size of the map over the next year to cover all of the galactic plane visible from the APEX site on Chajnantor, as well as combining it with infrared observations to be made by the ESA Herschel Space Observatory. We look forward to new discoveries made with these maps, which will also serve as a guide for future observations with ALMA,” ESO's Leonardo Testi, who is an ATLASGAL team member, and also the European Project Scientist for the Atacama Large Millimeter Array (ALMA) project, adds.

Some of the most prominent features visible in the full-resolution version of the image, according to an ESO press release, are (from left to right):

1. Messier 20 (the Trifid Nebula): A nebula containing an open cluster of stars as well as a stellar nursery. The name “Trifid” refers to the way that dense dust appears to divide it into three lobes at visible wavelengths.

2. Sagittarius B2 (Sgr B2): One of the largest clouds of molecular gas in the Milky Way, this dense region lies close to the Galactic Center and is rich in many different interstellar molecules.

3. Galactic Center: The center of the Milky Way, home to a supermassive black hole more than four million times the mass of our Sun. It is about 25,000 light-years away from Earth.

4. NGC 6357: A diffuse nebula containing the open cluster Pismis 24, home to several very massive stars.

5. NGC 6334: An emission nebula also known as the “Cat’s Paw Nebula.”

6. RCW 120: A region where an expanding bubble of ionized gas about ten light-years across is causing the surrounding material to collapse into dense clumps that are the birthplaces of new stars.

7. The Norma Arm: The region of the somewhat brighter emission extending over about 10 degrees on the right-hand side of the image corresponds to the position of the Norma Arm, one of the spiral arms of the Milky Way.