NGC 1087, NGC 3627 and NGC 4254 as seen with the VLT and ALMA at several wavelengths of light

These images of the nearby galaxies NGC 1087 (first and second column), and NGC 3627 (third and fourth) and NGC 4254 (fifth and sixth) were taken with the Multi-Unit Spectroscopic Explorer (MUSE) on ESO’s Very Large Telescope (VLT) and with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner. 

NGC 1087 and NGC 3627 are spiral galaxies located approximately 80 and 31 million light-years from Earth in the constellation of Cetus and Leo, respectively, while NGC 4254 is a grand-design spiral galaxy 45 million light-years away in the constellation Coma Berenices. 

The images are overlays of observations conducted at different wavelengths of light to map stellar populations and gas: green, red and infrared (g, r, i) emission, which is used to reveal the distribution of young stars; radiation from warm gas clouds of hydrogen (Hα), doubly ionised oxygen — [OIII] — and singly ionised sulphur — [SII] —, elements that signal the presence of newly born stars; radio waves emitted by carbon monoxide (CO) in cold clouds of molecular gas, which provide the raw material from which stars form. 

The images were taken as part of the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) project, which is making high-resolution observations of nearby galaxies with telescopes operating across the electromagnetic spectrum. By overlaying the images at different wavelengths, astronomers can better understand what triggers, boosts or holds back the birth of new stars.