Surveying Galactic Hydrogen Clouds.

Astronomers are using data from the National Research Council of Canada's radio astronomy array to make new maps of the Milky Way's hydrogen with 1-arcminute resolution. Recently they released findings on a complex "ecosystem" of atomic hydrogen clouds in Camelopardalis and Perseus.

Steve Gibson and Russ Taylor (University of Calgary) and Lloyd Higgs (Dominion Radio Astrophysical Observatory, DRAO) examined the Milky Way's Perseus sector as part of the Canadian Galactic Plane Survey (CGPS). "Understanding our origins, ultimately from the gas and dust between the stars, requires an understanding of the galactic ecosystem," Taylor says. "Counterbalancing forces within the dusty, gaseous interstellar medium govern the cycle of star birth and star death."

Cold hydrogen may be invisible to the eye but is very plain to radio telescopes by its emission at 21 centimeters wavelength. In this panoramic view, the DRAO radio data are color-coded blue, orange, yellow, and green to identify different regions within the gas clouds, distinguished by their different velocities. The image also includes data from NASA's Infrared Astronomy Satellite (pink) and the Westerbork Synthesis Radio Telescope in the Netherlands (gray-blue). The pointlike sources are distant galaxies with active nuclei. The giant "spur" at lower left is the nebula Lynds 679. It is 200 light-years long and was apparently driven out of the galactic disk by interstellar shock waves.