About this Image:The image is a composite of a radio image constructed from observations taken in several configurations of the Very Large Array at a wavelength of 20 cm for the MAGPIS survey with mid-infrared data taken as part of the GLIMPSE survey conducted by the Spitzer Space Telescope.
The radio data are coded red, the long-wavelength infrared data (at 8 micrometers) green, and the shorter wavelength infrared data blue-white; yellow regions in the image show places where both radio and infrared emission is prominent.
Normal stars are brightest at the shortest wavelengths, showing up as the myriad of blue-white points. Birthsites of the youngest massive stars show as yellow clumps -- radiation from the newborn stars heats surrounding dust producing infrared emission, while the ultraviolet light from these stars separates electrons from hydrogen atoms giving rise to radio emission.
More mature stars have managed to destroy the dust nearby leaving red cores surrounded by yellow, then green, shells as the temperature drops far from the stars.
The prominent red arcs mark the sites where massive stars have died in titanic explosions and blasted their gas light years into space at thousands of miles per second; their radio emission is produced as electrons, accelerated to nearly the speed of light by the outward moving blast waves, spiral in the Galactic magnetic field.
The diffuse green glow reveals the tiny dust particles that suffuse interstellar space along the band of the Milky Way; dark filaments superposed on this emission show regions where the gas and dust are so thick that no light can get through -- regions in which future generations of stars will form.
Investigator(s): Helfand, Becker, White
