Andromeda’s colorful rings – like swirls of dust, in the new image from the Herschel Space Observatory, will help astronomers to find the very coldest dust in our nearby galaxy. Image © ESA/NASA/JPL-Caltech/NHSC
The glow seen here, by a European Space Agency mission with important NASA participation, comes from the longer-wavelength, or far, end of the infrared spectrum, giving astronomers the chance to identify the very coldest dust in our galactic neighbor. These light wavelengths span from 250 to 500 microns, which are a quarter to half of a millimeter in size. Herschel’s ability to detect the light allows astronomers to see clouds of dust at temperatures of only a few tens of degrees above absolute zero. These clouds are dark and opaque at shorter wavelengths. The Herschel view also highlights spokes of dust between the concentric rings.
The colors in this image have been enhanced to make them easier to see, but they do reflect real variations in the data. The very coldest clouds are brightest in the longest wavelengths, and colored red here, while the warmer ones take on a bluish tinge.