WISE Image of California Nebula

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Knight of Clear Skies
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WISE Image of California Nebula

Post by Knight of Clear Skies » Mon May 25, 2020 7:11 am

I wonder if anyone can help me understand this WISE image of NGC1499 please?
NGC1499 WISE.jpg
This is a low res image screen grabbed from World Wide Telescope but it shows the main features of the nebula.

I'm having trouble understanding how the colour channels have been mapped to the four IR bands surveyed my WISE, which are listed here.
Band 1 – 3.4 µm (microns) – broad-band sensitivity to stars and galaxies.
Band 2 – 4.6 µm – detect thermal radiation from the internal heat sources of sub-stellar objects like brown dwarfs.
Band 3 – 12 µm – detect thermal radiation from asteroids.
Band 4 – 22 µm – sensitivity to dust in star-forming regions (material with temperatures of 70–100 kelvins).
I believe band 1 has been mapped to blue as it shows the stars. Band 4 is either green or red, but I'm not sure which one. Finally, I'm not sure if one of the bands has been discarded or combined with another one for the all-sky data set.

The red area appears to be centred on the star Xi Persei, I read somewhere that it's the bow shock from this massive runaway star. But is the larger green area at a higher or lower temperature, and what is heating it?

Any help would be appreciated.
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neufer
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Re: WISE Image of California Nebula

Post by neufer » Mon May 25, 2020 1:08 pm

https://www.nasa.gov/mission_pages/WISE/multimedia/pia13108.html wrote:
<<All four infrared detectors aboard WISE were used to make this image. Color is representational: blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is dominated by light from stars. Green and red represent light at 12 and 22 microns, which is mostly light from warm dust.>>
Art Neuendorffer

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Re: WISE Image of California Nebula

Post by Knight of Clear Skies » Mon May 25, 2020 1:27 pm

Thanks very much, looks like it's the same palette as the all-sky image. So band 4 is the red light and band 3 is the green (which doesn't match up very well with the descriptions in the wiki article).