A couple of new views of Andromeda from the Herschel space observatory are now available.
The first is a mosaic of data from Herschel’s Photodetecting Array Camera and Spectrometer (PACS) and spectral and photometric imaging receiver (SPIRE) … (click here) … the big deal is that cool lanes of forming stars are now revealed in the finest detail yet. The new image reveals some of the very coldest dust in the galaxy — only a few tens of degrees above absolute zero — colored red in the image.
By comparison, warmer regions such as the densely populated central bulge, home to older stars, take on a blue appearance.
Intricate structure is present throughout the 200,000-light-year-wide galaxy with star-formation zones organized in spiral arms and at least five concentric rings, interspersed with dark gaps where star formation is absent.
Andromeda is host to several hundred billion stars. This new image of it clearly shows that many more stars will soon to spark into existence … now that is fascinating.
On to the second image where below you can see ring-like swirls of dust filling the Andromeda galaxy.
The glow seen there comes from the longer-wavelength, the far end of the infrared spectrum, and gives astronomers the chance to identify the coldest dust. 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 coldest clouds are brightest in the longest wavelengths, and colored red here, while the warmer ones take on a bluish tinge.
This data, together with those from other observatories, reveal that other dust properties, beyond just temperature, are affecting the infrared color of the image. Clumping of dust grains, or growth of icy mantles on the grains towards the outskirts of the galaxy, appear to contribute to these subtle color variations.
So who said spying on the neighbors was not cool then? :-)