A Cold New View of the Milky Way Galaxy

A stunning submillimeter mosaic of the Milky Way Galaxy captures a portrait of the cold dust and gas swirling along the galactic plane.

The APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) maps the plane of the Milky Way Galaxy that's visible from the Southern Hemisphere at submillimeter wavelengths (0.87 millimeter, between infrared light and radio waves). The APEX data shows up in red and the background blue data were imaged at shorter infrared wavelengths by the NASA Spitzer Space Telescope as part of the GLIMPSE survey. The fainter, extended red structures come from complementary observations made by ESA's Planck satellite. The parts of the galaxy that are shown in the three slices are indicated at the right. (Click to enlarge image.)
ESO / APEX / ATLASGAL consortium / NASA / GLIMPSE consortium / ESA / Planck

Dust gets a bad rap. It blankets treasures like that childhood telescope left in the attic, and clouds of the stuff shroud celestial jewels in the center of the Milky Way. But appearances can be deceiving. Dust clouds that look like dark smog at visible wavelengths glow in the infrared thanks to the starlight they've stolen.

In fact, cosmic dust heralds star formation, aiding in starbirth and serving as raw material for future planets. Stars return the favor by manufacturing dust as they age, sending the fine, smoke-like particles out into space via stellar winds.

A new survey of the Milky Way lets cosmic dust shine in a 140- by 3-degree panorama. The 12-meter Atacama Pathfinder Experiment (APEX) telescope in Chile mapped the galactic plane that can be seen from the Southern Hemisphere at submillimeter wavelengths, capturing the glow of gas and dust just a few tens of degrees above absolute zero. The result is dubbed the APEX Telescope Large Area Survey of the Galaxy, or ATLASGAL, a treasure mine for astronomers studying star and planet formation and galactic evolution.

This map was then combined with Planck's all-sky survey at similar wavelengths. Although Planck doesn't capture images as sharp as APEX does, it has a better view of large, spread-out structures. For example, Planck's images helped Timea Csengeri (Max Planck Institute for Radio Astronomy, Germany) and her team find several spindly fingers of cosmic dust more than 100 light-years long, as published in Astronomy & Astrophysics(read the full article here). Such features are expected to appear between our galaxy's spiral arms based on simulations of the Milky Way's evolution — the features will be subject to future study.

The leftmost pane shows APEX data, the middle pane shows Planck data, and the rightmost pane combines the two for full effect. Planck's images helped scientists make out several spindly fingers of cosmic dust, marked with gray dotted lines and arrows.
Timea Csengeri & others / Astronomy & Astrophysics

“ATLASGAL has allowed us to have a new and transformational look at the dense interstellar medium of our own galaxy," said Leonardo Testi (ESO) in a press release. "The new release of the full survey opens up the possibility to mine this marvelous data set for new discoveries."

Mapping the galaxy one wavelength (or waveband) at a time: This image shows the Milky Way observed at submillimeter (first panel), infrared (second panel), near-infrared (third panel), and visible-light (fourth panel) wavelengths. (Find more information about this image in the press release.)
ESO / ATLASGAL consortium / NASA / GLIMPSE consortium / VVV Survey / ESA / Planck / D. Minniti / S. Guisard
Acknowledgement: I. Toledo, M. Kornmesser