Unusual colours in edge-on
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by
Budgieye
moderator
paolo123
I posted it in Radio Galaxy Zoo to see if there are any radio emissions coming from it, and yes, there are.
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JeanTate
why does it go from purple to orange then to yellow
As Budgieye said, the yellow (in the center) is because the bright stars there are mostly old. This image is at a scale where the different resolutions of the different bands (g, r, and i in this case) probably matter; that may explain the 'fringes' around the edges and some color gradients (like the red-greenish yellow of the star in the bottom left quadrant). Slight mis-alignment may also contribute.
The purple-white-blue is almost certainly recent (possibly on-going) star-formation. The reason you can see it on one side but not the other may be because it's occurring on one side only; however, there's a light-brownish (? you may call it something different) wedge above and to the right of the bulge, which transitions to white/green. This may be extensive dust, which causes the purple-white-blue of star-formation on the right to appear greenish.
Hope this helps, and happy hunting! 😃
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ccardamone
scientist
I definitely agree with JeanTate's color explanation.
But I'm wondering if part of the reason this one looks so strange (green shadows to the bottom right) could also be a bit due to poor image alignment between the filters in the SDSS composite color image. If I zoom out a bit, I notice the three round objects (maybe red galaxies) also appear to be red on the top and yellow on the bottom left.
http://skyservice.pha.jhu.edu/DR9/ImgCutout/getjpeg.aspx?
ra=7.72562354&dec=10.40877613&scale=0.09903&width=512&height=512&opt=&query=Posted
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Perhaps just an issue of viewing angle?
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Budgieye
moderator
In conclusion, the difference in colour is due to filter alignment artifact, and the bright purple area is real, and the galaxy is active, as shown by the Radio Galaxy Zoo data.
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