APEX lifts veil on
DR EMILY BALDWIN
Posted: JULY 2, 2009
A new atlas of the inner depths of our Milky Way Galaxy reveals thousands of previously unseen knots of cold cosmic dust - the potential birthplaces of new stars.
The survey was conducted by an international team of astronomers using the LABOCA camera (Large APEX Bolometer Camera) on the Atacama Pathfinder Experiment (APEX) telescope in Chile and has resulted in the largest map of cold dust ever produced at sub-millimeter wavelengths. The map covers a region along the Galactic plane some two degrees wide and 40 degrees long and is composed of 16,000 pixels.Colour-composite annotated image of part of the Galactic Plane seen by the ATLASGAL survey, divided into sections. In this image, the ATLASGAL submillimetre-wavelength data are shown in red, overlaid on a view of the region in infrared light, from the Midcourse Space Experiment (MSX) in green and blue. Image: ESO/APEX & MSX/IPAC/NASA
Known as the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL), the map shows the Milky Way at wavelengths between those of infrared light and radio waves, allowing astronomers to detect the dust clouds that could harbour the birthplaces of new stars, as well as reveal the structure of the crowded galactic core in greater detail than ever.
"ATLASGAL gives us a new look at the Milky Way," says Frederic Schuller from the Max-Planck-Institut fur Radioastronomie (MPIfR) and leader of the ATLASGAL team. "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."Colour-composite image of the Galactic Centre and Sagittarius B2. The centre of the Milky Way is home to a supermassive black hole more than four million times the mass of our Sun. Sagittarius B2 (Sgr B2) is one of the largest clouds of molecular gas in the Milky Way. This dense region lies close to the Galactic Centre and is rich in many different interstellar molecules. Image: ESO/APEX & MSX/IPAC/NASA
The clumps of dust measure a couple of light years across and have masses of between ten and a few thousand times the mass of our Sun, enough to give birth to even clusters of stars. The survey also picks out diffuse emission connecting the clumps, along with filamentary structures and bubbles blown out in the interstellar medium by supernovae and the winds of bright stars.
The survey will provide an extensive target list for forthcoming missions such as ESA's Herschel Space Observatory and the Atacama Large Millimeter Array (ALMA).Colour-composite image of the nebulae NGC 6357 (left) and NGC 6334 (right). NGC 6357 is a diffuse nebula containing the open cluster Pismis 24, home to several very massive stars. NGC 6334 is an emission nebula also known as the "Cat's Paw Nebula". Image: ESO/APEX & MSX/IPAC/NASA
"Every single compact source in the ATLASGAL survey shows us a place at which new stars are presently being formed," says Karl Menten, APEX principal investigator, director at MPIfR and team member of the ATLASGAL project. "We just have to point APEX or Herschel and, in future, ALMA towards these positions to observe the molecules associated with the dust to get a full picture of star formation throughout our Milky Way."