Roiling Heart of Cygnus X
Update: Phil Plait posted an article about this image in Slate!
Cygnus X is a largely dust-obscured region along the galactic plane about 4600 light years away. It's an immense area of active star formation, and I think it is also vastly underrated because of its relatively low-key appearance in visible light. The most famous part may be the Butterfly Nebula (IC 1318), but in fact that is only a fraction of the much larger structure at play. If our side of this star forming region had a larger opening in the dust, I have no doubt this nebula would rival well-known objects such as the Great Orion or Carina Nebulas. Far away astronomers in other galaxies may look at our Milky Way and take notice of this area as one of the largest areas of pink H-alpha emission.
Here in infrared, layers upon layers of dust and gas pile on top of one another, seemingly inseparable from one another. Dark tendrils of dust are dotted with red, young stellar objects. Bright red areas are warm dust captured at the 24 micron wavelength range. Other gas and dust is visible as bright, blueish tendrils, pillars, and blobs.
A curious red sphere encircling a star known as G79.29+0.46 is visible just left and below center. Given its structure, I could easily mistake it for a planetary nebula, but the star has been classified as a Luminous Blue Variable and the nebula a kind of ejecta shell.
Some things of note regarding the processing: The green channel, occupied primarily by W3, is of lower resolution. This makes the whole image appear a bit more blurry than I would like, and also causes many of the stars to have a green glow around them. In an effort to contain more of the nebula in the frame, some of the blue and red channels have had missing areas filled in with W3 data, notably around the right edge and lower left corner. I also combined luminance data from the two Spitzer channels to help sharpen the features in the image.
Red: Spitzer/MIPS1 (24μm)
Green: WISE/W3 (12μm)
Blue: Spitzer/IRAC4 (8μm)
North is up.